Science topic

Solvents - Science topic

Liquids that dissolve other substances (solutes), generally solids, without any change in chemical composition, as, water containing sugar. (Grant & Hackh's Chemical Dictionary, 5th ed)
Questions related to Solvents
Question
22 answers
PEO is water soluble, but how do you dissolve PEG in organic solvent such as chloroform?
Relevant answer
Answer
Khoa, before you go any further with your purification procedure, please keep in mind that the obtained triblock copolymer, synthesized under the given conditions, should have low molecular weight (Mn of ca. 2,400) and quite low glass transition temperature (below r.t.), in case of quantitative yield of the product. There is no information which lactide isomer you used. If L-lactide was used, the synthesized polymer would crystallize if precipitated, thus facilitating the purification by the dissolution-precipitation technique.
I have performed numerous syntheses of PEG-PLA copolymers with the use of all lactide isomers (L, D, rac, meso). I would recommend you dissolve the product in DCM at a concentration of 20% w/v, pour warm methanol into the solution (MeOH:DCM = 5:1 v/v) while stirring, and then put the flask in cold ice-water bath (still stirring) to precipitate the polymer and remove any unreacted monomers from the product. No lactide and much lower tin content would be detected in the thus purified product. If you would like to further reduce the tin content in the resulted polymer, you should dissolve a small amount of citric acid or another chelating agent in the non-solvent (MeOH) before precipitating the polymer. This reduced the tin content in my samples from 500 to 10 ppm (as indicated by AAS) which is highly desirable for pharmaceutical and biomedical applications.
The PEG-PLA copolymers are water white when melted and form white powder or fluffy precipitates, depending on molecular weight of both PEG segment and the final polymer, and polymer composition as well. However, when lactide is polymerized at higher temperatures, in the presence of high amounts of commercial, unpurified tin octoate, the reaction mixture often turns yellow or brown with a prolonged time. I would, therefore, suggest you modify the polymerization conditions for the synthesis of low molecular weight PLA (Mn < 5,000) as follows: lower temperature (130 deg C), shorter time (6 h) and lower SnOct content in feed ([LA]/[SnOct] = 2000 mol/mol).
n-Hexane as a non-solvent for the purification of PLA by the diss-pptn method is definitely a bad choice since unreacted lactide monomer does not dissolve readily in non-polar solvents and remains in the precipitated product.
Question
7 answers
The method is well established and there are many books and articles on how such calculations should be conducted. But all I can find is works on polymer blends or polymer/drug conjugates and nothing on polymer/solvent systems.
Relevant answer
Answer
Hi Abolfazi,
we have recent;y published a work on the solubility of P3ATs in THF. We have calculated the FH interaction parameters via model potential molecular dynamics simulations. You will find also a brief summary of the theory behind the method in the Supporting Information.
You can find the paper here: http://dx.doi.org/10.1021/ma401345n
Claudia
Looking for a non-hazardous solvent for Nylon 6?
Question
18 answers
I am looking for a non-hazardous solvent for a blend of Nylon-6/PAN? I prefer avoiding any types of acids due to further problems it may raise. Any recommendations, please?
Relevant answer
Answer
Quite a challenge. DMSO is THE non-hazardous "super" solvent of choice for many technical polymers ... but Nylon-6 is not soluble in DMSO (even upon heating aup to 150°C). I am afraid that you have only very challenging options to consider. Among those: - to use low MW Nylon-6 (you probably have to make it yourself) - use a Nylon-6 copolymer ( you probably have to make it yourself) Generally speaking, introduction of a small amount of comonomer (1%) can dramatically reduce the melting point of semi crystaline polymers such as Nylon-6, and facilitate solubilisation.
Question
4 answers
Catalysis
Relevant answer
Answer
Thanks for the answer Eric.
Question
3 answers
Plant biology.
Relevant answer
Answer
For hexanic plant extracts, you can use a combination of hexane:ethyl acetate or toluene:ethyl acetate in the ratios ranging from 6:4 to 9:1. You will surely get good separation on TLC plates. Use anisaldehyde-sulfuric acid reagent for spraying the plates followed by heating at 110 C for 10 minutes.
Regards
Question
1 answer
My extract is lipid. How can I work with MIC if it is not soluble in water?
Relevant answer
Answer
Hi...Try to dissolve in DMSO/ methanol/hexane/chloroform/benzene/diethyl ether; you can warm a bit to increase dissolution. but include these solvents as the control.
Question
2 answers
I want to know about a dispersing agent and refractive index of polyNIPAM.
Relevant answer
Answer
We are using Dioxane for the purpose.
Question
8 answers
Hello,
I'm trying to dissolve hexane extracts of some plants. The extracts are very viscous, and I need make solutions at 50mg/mL. After, I will test them in in vitro biological assays. So, the solvent mustn't be too agressive.
It already have been tested: Ethanol 90%, Methanol 75%, Acetone 70%, Tween 80 (10%) and DMSO (100%). None of all dissolved the extracts completely.
Can anyone suggest me other solvents?
Relevant answer
Answer
There is no solvent can be make the extraction completely . This due to the multi components of molecules in each plant extraction.you can use pure pentane as non polar solvent and dioxane in different ratio.
Question
4 answers
I need to soublize silica powder for NMR analysis to find out bio-active compound.
Relevant answer
Answer
This from Inorganic Ventures--I have used this technique for metals analysis via ICP-AES.
Quartz powder is best dissolved by fusion with sodium carbonate. You may want to add some HF to the final solution to stabilize the Si for long-term stability.
The following is a general preparation guide for carbonate fusions:
1. Make certain that the sample is well mixed with the sodium carbonate.
2. A five 9's pure sodium carbonate is recommended. This is available through E.M. Science.
3. Mix the sample with the flux at no more than a 1:20 ratio. Typical sample to flux ratios are in the area of 1:10.
4. If organic matter is present, there are two options: 1) The sample is mixed with the flux initially and heated slowly to 500 °C for ~2 hours before bringing to full temperature; or 2) the sample can be pre-ashed at 500 °C and then the ash is mixed with the flux.
5. Use Pt as the crucible container material.
6. Perform the fusion at 1000 °C in a muffle furnace. Avoid flames--this fusion is difficult to perform in a flame due to the high melting point of the sodium carbonate.
7. Most fusions are complete in 15 minutes and some require up to 45 minutes.
8. Dissolve the fuseate in dilute HCl (1:1) (for samples high in Si, the use of some HF may be needed).
Question
6 answers
I have tried to find the original paper and some justification for using it, but so far no luck.
Relevant answer
Answer
Well, now it is well proved that the performance of Suzuki-coupling is excellent with dioxane as a sole solvent in case of Pd or Non-Pd catalysts. You can find a lot of references in this issue.
But, we don't have sufficient reference about the aqueous dioxane binary solvent system in Suzuki coupling.
Although, it seems that, aqueous dioxane has some great advances in solubility of both hetero and homogeneous catalytic system, their has some drawbacks as well as.
Anyway, from the following link you can find your references on "aqueous dioxane binary solvent system used for Suzuki cross-coupling reactions". Hope you will find your answer....good luck!
Question
8 answers
We are trying to digest a difficult target with tobacco etch virus protease and was wondering if anybody has experience using this enzyme in organic solvents? Would it be stable in for example 50% ethanol or 50% acetonitrile?
The protein we want to digest is very hydrophobic and surfactants work to some extent to solubilise but not very well.
Relevant answer
Answer
I would try doing the digestion in varying amounts of freshly made and filtered urea, from 0.2 M to 2 M (check pH to make sure it is not altered and use 100 mM of buffer), since some enzymes are stable in high urea concentrations (a N-terminally truncated FIV PR and human topoisomerase I are examples) while the target protein may not be as stable and urea will certainly increase the solubility of a hydrophobic protein.
You could also try different concentrations of dimethylformamide if the TEV PR is active in it, since DMF is a good solvent for hydrophobic peptides.
Question
1 answer
The experimental determination of HSP for polymers is performed using a set of solvents of known HSPs. Can a similar procedure be used for the estimation of HSP for a particular liquid mixture? Classical methods involve the use of thermodynamics and/or group contribution methods, but for multicomponent liquid mixtures these methods could be difficult or inaccurate, and a direct experimental determination would be desirable. Preliminary tests to validate this idea were done using a pure liquid of known HSP, mixing it with a standard set of solvents and calculating its HSP using the HSPiP software. However the accuracy of the results was not good enough. Any suggestion? Thanks.
Relevant answer
Answer
Dear Dr. Hernandez, discussion about solubility parameters ( rich in apologists of HSP excellence ) look at http://shootingcupoche.com/post/How_can_I_use_solubility_parameters_to_show_that_a_polymer_is_soluble_in_a_solvent
I have unfolllow this subtopic, because believe that it is unequal replacement of full and direct set of data (real solubility) on indirect (calculated and approximated) set of derivatives. Some exclusions from HSPiP was corrected recently, but cited by Wiki example with poly(vinylfluoride), polymer shape dependence and your example lead to grievous resume - solubility parameters and HSPiP are templet for house painters. But not scientific instrument with predictive power.
In your case I think situation may be caused by (strong) interaction between different solvents molecules. If the interaction between the solvent is weakly dependent on their molar ratio, the parameters can be obtained. Probably) Be sure, you are not alone with such problem - I've seen similar problems question on RG from other people.
Question
12 answers
For the induction of type 2 diabetes.
Relevant answer
Answer
Alloxan is relatively unstable in aqueous solution, if you keep it for a long time. Also preparation of the solution and dose administration is a tricky part. You have to be careful about temperature and speed of dose administration.
My suggestion would be,, you use citrate buffer solution, maintain pH 4.4 and administer the dose as quickly as possible. Before that keep the buffer on ice and mix alloxan prior to administration. 150 mg/kg dose will produce a good number of hyperglycemic animals within 3-4 days.
So, after alloxan administration, 3-4 days later, check the animals for hyperglycemia and select them for further studies.
Is the External Iteration in the PCM calculation available in g09 also available in g03?
Question
4 answers
This is for excited state TD DFT calculation in solvents (g03).
Relevant answer
Answer
It does not. SCRF=ExternalIteration was added to g09. Look at: http://www.gaussian.com/g_tech/g_ur/k_scrf.htm PCM Performs a reaction field calculation using the integral equation formalism model (IEFPCM). This is the default. Some details of the formalism and the implementation have changed with respect to Gaussian 03, as described in [Scalmani10]. IEFPCM is a synonym for PCM. G. Scalmani and M. J. Frisch, “Continuous surface charge polarizable continuum models of solvation. I. General formalism,” J. Chem. Phys., 132 (2010) 114110
Question
14 answers
I have an old silver paste which has become more or less solid. I want to reuse this paste, but i don't know the suitable solvent.
Relevant answer
Answer
Acetone is good solution if you want your paste to stay uncontaminated and conductive. If you dissolve silver paste in excess of acetone, you could see nice convection cells - http://en.wikipedia.org/wiki/Rayleigh-B%C3%A9nard_convection
Question
2 answers
In Lyophilization formic acid can not be removed, so can in this case we say co solvent?
Relevant answer
Answer
I don't understand very well your question. You want to lyophilize a sample? Or you want to separate a mixture by liquid chromatography, and then lyophilize some fractions obtained? Formic acid is commonly used in liquid chromatography to acidify an eluent.
Question
4 answers
Mainly what type of solvents can be used?
Relevant answer
Answer
Yes, I suggest using oleyl alcohol. Oleyl alcohol is a good extractant, because of the similarities of the alkyl chain it will dissolve well the oleyl aldehyde, easy to separate it by distillation, because oelyl alcohol bp. is higher than oleyla aldehyde b.p.
Furthermore, because oleyl alcohol is a non-toxic solvent, you have a chance to do the fermentation continuously with simultaneous extraction with oleyl alcohol. I did similar reactions to produce butanol in the presence of oleyl alcohol.
First, I would measure the distribution coefficient between H2O and oleyl alcohol for the oleyl aldehyde. I expect high value, but it worth trying to determine to determine the solvent/ferment liquor volume ratio for efficient extraction .
Question
16 answers
To observe powder particles using TEM, we must dilute the powder with solvent (by sonication, mixing, or something), before dropping them onto the TEM grid. What am I curious is which solvent is more appropriate for diluting the powder, acetone or DI water, or another solvent? How they will effect the status of the powder particles and then the observation result? Could you please share your opinion?
Best regards
Relevant answer
Answer
Ethanol is the best option... as Dr. Klemm already said ....
you should be careful about few things....
1) the solvent should not react with the powder.... as distilled water can react in case of metal powder and form oxides..... be aware of that.....
2) It should evaporated fast....
3) the solute (powder) can disperse in the solvent.....
4) grid size (copper grid) no. of mess/area......select according to the particle size of your powder......
5) before putting it in TEM, the grid should be completely dry (follow the standard procedure)
most of the cases Ethanol used as a solvent ...as it is not react with the powder even it is metallic....
for ceramic powder / polymers you can even use Deionized water.... depending upon there disperse nature in DI water......
Question
17 answers
I would like to synthesize propargyl methacrylate for research involving click chemistry. I wanted to buy it, unfortunately it's classified as a "Dangerous Product" in Singapore and the chemical companies can't import it from US. So I looked for literature online that synthesize propargyl methacrylate, and I found one that reacted propargyl alcohol to methacryloyl chloride in the presence of triethylamine and using diethyl ether as a solvent. <http://onlinelibrary.wiley.com.libproxy1.nus.edu.sg/doi/10.1002/pola.22367/pdf> The problem is Sigma-Aldrich doesn't seem to sell diethyl ether either because of several concerns about it. I would like to know what alternative solvent could I use for diethyl ether? And what should be the properties of the solvent that I should consider in looking for a substitute? I would also appreciate it if anyone could explain the necessity of triethylamine, does it reduce the potential violent reaction that can form due to the production of hydrochloric acid?
Relevant answer
Answer
I think Novozyme-435 may help for typical esterifications. The reaction condition are temperature at 60C and it should never cross beyond, usually t-BuOH is the solvent system used. My personal experience was with fatty acid esterification with propargyl alcohol.
Please remember, this reaction works for acid+alcohol esterifications, i.e., we can choose methacrylic acid and propargyl alcohol.....as reactants
If it works please reply me....
Question
1 answer
Compound is insoluble in water.
Relevant answer
Answer
You need to use Organic Normal Phase Chromatography if you want to get separation . I know of excellent column for ONP but I do not experience with using ONP solvents for MS. I think you would have to introduce small % of methanol in addition to hexane or other ONP solvents.
Maria
Question
3 answers
I have been facing some troubles with DMSO in my experiments in rat aorta. DMSO has a direct effect in the preparation, which interferes on the effect of the extract.
Relevant answer
Answer
Hi dear
Because DMSO act as  vehicle therefore didn't effect the the aortic relaxation and contraction depending on the concentration that you used for the preparation of the extract, it is important that the concentration of DMSO not larger than 5% of solution inside tissue bath
Dr. Mudhir 
Who has some information about solving Gd2O3 in HCl?
Question
12 answers
I want to solve 0.05 Gd2O3 in HCl but it becomes unstable and precipitate.
Relevant answer
Answer
0.01 mol/lit
Question
5 answers
My solute which is an antioxidant (0.25g) dissolves easily in acetone (25ml) (99.5%).
Whereas my solute (0.25g) does not dissolve in 25ml methanol (99.9%). However it only dissolves when 0.25g in 250ml methanol.
By the way it can't dissolve in water at all.
Relevant answer
Answer
hmm
finally i been told what the solute is. Its a powder containing xanthone and some wall material? so it seems to be a very hydrophobic fella.
I need to run antioxidant assay on it. Hmm im figuring if methanolic extract of it is a good idea (which seems to be most paper favourites). perhaps with acetone or erm other solvent that is more non polar.
Is there a single solvent that can dissolve PAN, Nylon-6 and PAM together?
Question
20 answers
see above
Relevant answer
Answer
If PAM is polyacrylamide, all you polymers can be dissolved in DMSO.
Question
1 answer
What solvent should I use to solubilize the lipid extract, that could also be used as negative control for an antibacterial experiment?
Relevant answer
Answer
Chloroform and methanol solvents 2:1
Question
1 answer
I want simple qualitative methods to evaluate the evaporation of volatile solvents from a solution.
For example, if I have DCM in a solution and I am evaporating it, how can I know that after one hour if it is completely evaporated from solution?
Relevant answer
Answer
Simple way weighting or observing the constant weight on the balance. Or using the headspace technique e.g. SPME and determine by GC
Question
1 answer
We can extract chlorophyll using different solvent like DMF, ethanol, acetone etc., but what is the the exact mechanism for acetone?
Relevant answer
Answer
According H. K. LICHTENTHALER (see below) chlorophylls possess a phytyl chain which is bound to a porphyfin ring system. The possession of the phytyl side chain, which is esterified to the carboxyl group of the ring, gives the chlorophylls their lipid character.
Moreover, chlorophylls are fat-soluble compounds that can be extracted from water-containing living plant tissue by organic solvents such as acetone, methanol, or ethanol, which can take up water. Though aqueous solutions of these solvents are also suitable (and may sometimes be preferable) for extraction, their water content should not exceed 5 or 10%. The widely used method to extract isolated chloroplasts by 80% aqueous acetone does not fully extract the less polar pigment chlorophyll a. An addition step of extraction with 100% acetone is needed to guarantee complete extraction.
H. K. LICHTENTHALER, 1987. Chlorophylls and Carotenoids: Pigments of Photosynthetic Biomembranes. METHODS IN ENZYMOLOGY, VOL. 148, pp 350-382.
Question
4 answers
The compound I have only partially dissolved in DMSO and I am not sure how to characterize it. I am not able to get a reasonable NMR spectrum. What do you recommend?
Relevant answer
Answer
and mass spectrometry
Question
2 answers
I need to prepare a solution of bumetanide (inhibitor of NKCC1) to deliver into the brain. We dissolved the drug in DMSO and diluted with saline. The drug precipitated out of solution. So we pH'd it to 7.35 but it took a ridiculous amount of time because our pH meter would take minutes to change its reading to match the litmus paper.
1) Is the pH meter busted?
2) Are there any simple solvents that would be harmless to brain tissue that would make this easier?
3) Are there any sorts of simple buffers?
4) Am I just going to have to suck it up?
Relevant answer
Answer
This product is soluble in ethanol (50 mg/ml), with heat
as needed, yielding a clear to slightly hazy, colorless
to yellow solution. It is also soluble in acetone and
alkaline solutions, slightly soluble in chloroform and in
ether, and very slightly soluble in water.
Martindale The Extra Pharmacopoeia, 31st ed.,
Reynolds, J. E. F., ed., Royal Pharmaceutical
Society (London, UK: 1996), pp. 836-837.
Question
8 answers
Solvent mixture MeOH/Aceton (about 1:1 volume ratio) is evaporated after reaction and condensed in recovery for using in the next reaction.
So we are looking for a simple method to quickly determine the ratio of these two components in the condensate. We would like to use something which is simpler than GC, for example.
Anybody have an idea?
Relevant answer
Answer
Draw a reference curve of the UV absorption at e.g. 254 or 280 nm (check which one is best) and then use this measurement for a quick check of the acetone content.
André Verhecken
Question
4 answers
Solvent for 3-​Aminopropylphosphonic acid.
Relevant answer
Answer
I would guess any polar protic solvent (e.g. methanol, ethanol) would do the trick, but the compound is a zwitterion which always plays tricks on solubility. Some amino acid zwitterions are actually more soluble in more lipophilic solvents e.g. ethyl acetate and dichloromethane.
If you are not dependent on pH, you can buffer the solution slightly acidic or basic to improve the solubility.
Question
2 answers
The impurities are determined gravimetrically? How many g do we need of the sample? Is hexane the best solvent?
Relevant answer
Answer
Which impurities? Pesticides? Rancidity? Foreign matter (filth)? What are you testing for?
Question
29 answers
I want to assay cell viability with MTT powder from Merck company. What is best solvent of MTT powder for cell viability assay?
Thanks.
Relevant answer
Answer
We dissolve 1G MTT (Sigma, M5655-1G) in 200 ml PBS (5 mg/ml). Aliquot it in 5 ml tubes and store it at -20. Add 20 ul to 200 ul media containing tested cells plus medium (after incubation time). Then add 50 ul MTT stop solution (formazon solvent). Incubate for 4 hours at +37. Read OD at 570 nM. 
Question
18 answers
Deep Eutectic Solvents (DESs) are a solvents obtained by mixing solid compounds, such as choline chloride and sugar, organic acid, obtaining a eutectic mixture with a melting point that is much lower than that of the individual components.
Benefit: Absolutely green solvent. Especially when use is not chlorine compounds such as choline chloride
Relevant answer
Answer
Interesting and very timely discussion. However, I also think 'absolutely green solvent' is an exaggerated term. It is true, that in recent years we have witnessed huge number of published research on ionic liquid (IL) containing systems and applications. When compared to well established and conventional processes, by far it is not either economically feasible or practically applicable (toxicity, biodegradability issues) to use ILs. But we have to keep in mind one property of ILs - designer nature/tunability - that's where the strength of IL-based research lies. Of course in order to implement them in a certain process we have to start testing simpler systems, i.e. first generation ILs (may contain a whole lot of drawbacks). In the last decade the learning curve regarding suitability of a particular ILs for a certain application has considerably improved. As Boyan and Michal indicated, although DESs are analogous to ILs, but for certain conditions like working under vacuum, ILs are by far the best choice. I think we have still a lot to see. The last decade was just a warm-up !!
Question
3 answers
Recently, I'm working on a project involving the use of n-butanol and ethyl acetate for phytochemical extraction. However, I'm confused with regards to the polarity of these 2 solvents, based on the information on the internet , the polarity index of n-butanol is 4.0 and ethyl acetate is 4.4. As far as I know, the higher the polarity index, the greater the polarity. However, based on literature, it was stated that n-butanol is more polar than ethyl acetate. Can you clarify which is actually true? I'd appreciate your help in this matter.
Relevant answer
Answer
Dear Charles,
That is a good question. What happens is that the polarity index is just an approximation of solvent properties. There are several: Hildebrand solubility parameter, Snyder polarity index, Hansen solubility parameters, etc. All are indirect ways of looking at the termodynamics of the solution, and are just an indication of what may happen in terms of solubility. Hansen solubility parameters, for example, try to account for hydrogen bonds, polar and London forces between molecules. If you are interested, start with Wikipedia and then proceed to the second link:
Check this image and locate your solvents:
You will see that n-butanol is not very polar (in the sense of dipolar bonding), but that it is higly capable of hydrogen bonding; while ethyl acetate is about the same polarity, but poorer in terms of hydrogen bonding. There is one Hansen parameter missing, which is associated with dispersion forces, which are about the same for both solvents.
Now to the practical extraction: if you want to dissolve a target molecule from a plant matrix, there are two things you must also worry about: interaction of the solute with other substances (e.g. carbohydrates, proteins and lipids in the material), and the need to permeate or dissolve complex structures such as cell walls and membranes. All considered, I guess that you will need experimental data as much as the theoretical basis here.
Good luck!
Question
16 answers
-
Relevant answer
Answer
The sesquioxide or iridium (III) oxide (Ir2O3) is considered soluble in H2SO4 (also in hot concentrated HCl). The Iridium (IV) oxide, IrO2, is considerably more difficult to dissolve, being however also soluble in hot concentrated HCl (after hydration). It seems that previous reduction of IrO2 to Ir2O3 might be helpful if use of HCl is to be avoided. For the case of a thin-film layer of IrO2, the localized application of reducing flame might perhaps be considered, besides heat treatment in reducing atmosphere or immersion in strong reducing solution.
Question
2 answers
What is the physical significance of the activation energy (Ea) and the pre-exponential factor (lnAs) in the Arrhenius type-equation for viscosity of liquids, especially for organic solvents? Is it related to enthalpy of vaporization? I think it may be that there are some correlations between these two parameters, and the equation {ln(viscosity) = lnAs + Ea/RT} is more than a completely empirical equation. We must think for science, even it we do not find anything.
Relevant answer
Answer
One recent interpretation is given by Frech and Petrovsky. http://pubs.acs.org/doi/abs/10.1021/jp408899y. It depends very much on the temperature range examined, as most organic liquids eventually deviate from the Andrade (Arrhenius) T dependence as they are cooled. Angell has written extensively on "strong" (Andrade) and "fragile" ("non-Andrade") liquids.
See also Tyrrell and Harris, Diffusion in Liquids, Butterworths, 1984, p. 285 ff for criticism of activated jump theories.
Question
9 answers
Chromium.
Relevant answer
Answer
I don't know which amount of Cr(III) do you need in solution, but even less concentrated sulfuric acid than 10% would work fine. I would use 1% and check that the final pH when you dissolve your chromium salt remains acidic. I would suggest to keep the solution at pH not higher than 3.
Question
2 answers
Added 50% ethanol by mistake at washing step during Trizol-extraction, now wondering how can I retrieve my RNA from it?
Relevant answer
Answer
Usually you can precipitate RNA in ethanol/sodium acetate.
So I would say to add absolute ethanol (to have 75% etOH final) and 1/10th volume of Sodium acetate 3M and precipitate on ice for 10min or longer (overnight in a -20°C freezer), centrifuge at high speed for 10min, remove carefully the supernatant, dry the pellet in a speedvac for 5min and resuspend finally in DEPC treated water.
Hope this helps. Good luck.
Question
7 answers
Kinetic study and/or total antioxidant activity study of antioxidants from different types of tea
Relevant answer
Answer
Hi John
Very good colleague of mine (First author) has a number of different assays for analysis and he has published only few in this article.
Vuong,, Q; V., Nguyen, V. V., Golding, J. B., & Roach, P. D. (February 2011). "The content of bioactive constituents as a quality index for Vietnamese teas.". International Food Research Journal, 18 (1).
How to dissolve TiO2 nanopowder?
Question
36 answers
I want to dissolve TiO2 nanopowder. Is it will be dissolve in solvent (polar or non polar) or in acid.
Relevant answer
Answer
"dissolved"? after dissolving them no nanoparticles any more? or did you mean "dispersed"?
Which solvent do you choose to prepare DPPH solution: methanol or DMSO? Are there any significant differences between these solvents?
Question
65 answers
So far, I've used DPPH solution in DMSO because my samples of naringenin derivatives are only and only soluble in DMSO solvent. The maximum absorbance was determined at 523 nm. Reviewing the literature I've noticed that some people used samples dissolved in DMSO and DPPH dissolved in methanol. Is it good that I use DMSO solvent to prepare DPPH solution? Do you know if DMSO has influence on radical scavenging effect or antioxidant activity? Please write.
Relevant answer
Answer
Because your samples (naringenin derivatives) are soluble in DMSO and you want to evaluate the DPPH scavenging of the same, so it is preferred to use DMSO as solvent to dissolve DPPH if possible. But you should dissolve your standard or reference compound in same (DMSO) which is more necessary to get exact comparative view.
Question
3 answers
Stock solution is at 10 mM in DMSO - a lot of publications use this compound at a concentration higher than 10 uM but when I try, it systematically precipitates. Does someone have a trick? Maybe it reacts with a particular compound of the medium?
Relevant answer
Answer
Try to use less concentrated stock in DMSO. Switch to another solvent (like methanol). But keep in mind this compound is not selective AMPK inhibitor. It hits a lot of other targets just as potently.
Question
5 answers
Currently, I am researching about separation of compounds in essential oil. This oil has polar and non polar compounds that need to be separated. I use only ethanol for solvent. I have two different adsorbents, polar and non polar, used separately for comparison. I read about similar research is using more non polar solvent. I knew that I should do like what this article do but I didn't because my advisor told me to use ethanol. And then my advisor ask me back why I chose ethanol and I don't know why. I will look for the reason in textbook but could anyone suggest the reason too?
Relevant answer
Answer
This is simply because ethanol dissolves polar as well as nonpolar compounds at the same time.
Question
2 answers
If possible please include the references.
Relevant answer
Answer
Hi
following link will help you:
Question
9 answers
Doing research in Endophytic fungi. Want to extract secondary metabolite from Endophytic fungi.
Relevant answer
Answer
Peter Hufendiek is on target here. Assuming what you are after is a reasonably polar selection of metabolites I'd do a 80% EtOH extraction. Then partition (in a separating funnel) with hexane and 60% methanol-water.  This removes the non-polars. Evaporate off most of the methanol (Rotovap at 40-50) - just reduce the volume to about half - then extract this (separating funnel again) with EtOAc, CH2Cl2 or CH3Cl - dry the organic layer with a suitable dessicant ( I suggest Na2SO4 since  MgSO4  can absorb some terpenes) , evaporate the  extract - this should be the fraction you are after. However keep all the other fractions - you never know.  You can always reextract them if you miss the target compound.
Question
2 answers
I am looking for a better solvent to swell a FKM rubber.
Relevant answer
Answer
Hi Celia,
try EtOAc and THF
Question
2 answers
We tried to dissolve yttrium nitrate hydrates in ethanol and discovered that their solubility varies depending on the source, in spite of nominally the same chemical composition. Usually given as Y(NO3)3*xH2O, the compound purchased from Aldrich practically did not dissolve in absolute ethanol, whereas that from other suppliers dissolved easily at least up to 1.0 M. What could be the reason for such strange difference? Purity was 99.9% or better in all cases.
Relevant answer
Answer
If the solids have exactly the same composition, there is no really a clear answer for that. Solubility depends on so many things... Maybe it is just a kinetic problem. Different suppliers may differ in: particle size, crystallinity (check XRD), number of hydration molecules (4, 6, etc.). Regarding crystallinity, amorphous dissolves usually better than crystalline. "Ageing" is also a variable in some particulated solids.
So... for a rigorous answer a complete characterization of the different solids shoud be performed.
SInce water would really help to dissolve nitrates, probably the difference between aldrich and the rest of suppliers is in the number of hydration molecules.
Question
3 answers
Previously we performed successfully a reaction of 150 deg C by using solid acid catalyst under CEM Microwave reactor for half an hour but now I am unable to do the same reaction by using butyl imidazole based catalyst instead of solid acid catalyst. The solvent evaporated out after 140 deg C within a minute.
Relevant answer
Answer
Chemical components present in the system interact differently with microwaves, depending on their polarity. Polar solvents or reagents couple
well with microwaves and reach high temperatures in a short time.
Non-polar solvents are transparent to microwaves.
Temperature-Time:
If the reaction has already been performed with conventional heating, take in consideration the standard reaction temperature and time. Based on these two parameters, consider the Arrhenius equation, e.g. how the time decreases when the temperature increases. This law defines that every ten degrees that the temperature
increases, the time of the reaction is halved.
For example, if a reaction is run in EtOH at 80°C for 8 hours and the
Arrhenius law is applied, the time is reduced in accordance to the table
below:
Temperature (°C) Time
80 8 h
90 4 h
100 2 h
110 60 min
120 30 min
130 15 min
140 8 min
150 4 min
By increasing the temperature of 70°C, the time is reduced from 8
hours (480 minutes) to 4 minutes.
This simple procedure can be applied to all the reactions.
Reference: Basic Guidelines for Microwave Organic Chemistry Applications
By Laura Favretto
Microwave Organic Chemistry.
Question
27 answers
The solvents I want to use are: Petroleum ether, Diethyl ether, n-butanol, Chloroform, Ethyl acetate, Acetone, Methanol and water.
Relevant answer
Answer
 Cyclopentane/Heptane/Hexane/Iso-Octane/Petroleum Ether
 Cyclohexane
 Toluene
 o-Xylene
 Ethyl Ether
 Dichloromethane
 n-Butyl Acetate/n-Propyl Alcohol/Tetrahydrofuran
 Chloroform
 Ethyl Acetate
 1,4-Dioxane
 Acetone/Methanol
 Acetonitrile
 Dimethyl Sulfoxide
 Water
Question
15 answers
What solvent will be best for extract preparation and which will give good results for stigmasterol estimation? The tissue is part of a tomato plant.
Relevant answer
Answer
Methanol or ethanol for UV and HPLC and Hexane for GCMS
In a Click reaction with an azide, an alkyne, CuSO4.5H2O and sodium ascorbate, what is the order of the products to put in the beaker for the reaction?
Question
85 answers
I am trying to create a chemical sensor on a gold electrode. To make this, I need to know the order of the products to put in the beaker and the approximate quantities in the Click reaction. Indeed, I have tried some ways for the Click reaction but it failed every time. My azide compound is grafted on a benzene which is grafted on the gold electrode. My alkyne compound is the ethynylferrocene. My azidation takes place in acetonitrile and it works well. I also do not know what solvent I must use for the Click reaction. Indeed, ethynylferrocene is not soluble in water whereas it is in acetonitrile. And the majority of Click reactions take place in a mixture of water and ethanol. I also need mild conditions due to the weakness of the electrode.
Relevant answer
Answer
First mix copper and ascorbate in water until you obtain an heterogeneous orange/yellow solution, then add it to your pre dissolved alkyne/azide mixture. In my cases it worked with those solvents: THF, dioxane, DMF, t-butanol, MeOH and water. For lipophilic compounds, dioxane is my favorite one! Good Luck
Question
10 answers
Graphite Spray
Relevant answer
Answer
acetone dose not solve the carbon.!I have tried before
Question
15 answers
I am working on GC-HS for residual solvent analysis. I am using PE-WAX 30 meters capillary column. I have observed splitting of peak of methanol and Dichloromethane solvent during analysis. The concentration of both solvents is 1000 ppm. They both are eluted at the same RT. How can I modify the technique to get better separation and sharp peaks?
Relevant answer
Answer
Ph.Eur. HS parameters for water as solvent:
oven: 80°C 60min; needle,valve, transfer line 85°C; pressurization 30sec; injection volume 1ml (this is for a loop based system). For pressure balanced injection : oven 80°C 60min; needle 85°C; transfer line 90°C ; pressurization 1 min; inject 0.04 min; vent 20 sec; withdraw 1 min
vial pressure should be higher then 50kPa
You will have troubles to make a 1000 ppm solution of dichloromethane in water , try to dilute from a dichloromethane in DMSO solution.DMSO and water produce heat on mixing so take care not to loose volatiles. As alternative You can use DMSO or DMF as solvent (other parameters).
Ph.Eur. GC parameters for wax column:
30m; 0.53 or 0.32 mm ID;film 0.25µm;carrier 35 cm/s(He is best N2 will work); split 1/5; injector 140°C; detector 250°C; oven 50°C 20 min, 6°C/min to 165°C, 165°C 20 min.
In your case you can change the oven program to 50°C 10 min, 40°C/min to 165 min for 20 min.
methanol~ 3.2 min, dichloromethane ~3.7 min
A 624 column will give a better separation.
Headspace is a very nice and clean technique but what happens in the vial is quit complex so you will have to build up some expertise
Question
15 answers
Product = 9,10-dibromo stearic acid
Relevant answer
Answer
Its very simple. Add water in mixture, (DMSO is highly water soluble) extract it with carbon tetrachloride or n-hexane. Your product being nonpolar will prefer to go to the nonpolar solvents. evaporate to get your product.
Question
14 answers
Polycarbonate is resistant to Acetone, Methanol or any other common solvents.
Can someone suggest different solvent for PC?
Also I came across a paper which had water with surfactant as a good option for PC solvent.
How true is that?
Please do suggest some solvents for PC.
Relevant answer
Answer
CH2Cl2 is commonly used for viscosity measurements and molecular mass determination
Question
1 answer
. However, so far I have been unsuccessful. I tried to dissolve them in pure DMSO, or 5% dichloromethane
Relevant answer
Answer
I work with murine lymphoma cells and when i have to use non polar extracts i dissolved them in EtOH 10% supporting me with a vortex and a sonicator. At this concentration, the EtOH shows only about a 15% of citotoxicity and decreases as i make serial dilutions. I hope this info helps you.
Question
3 answers
Less aggressive solvents are preferred.
Relevant answer
Answer
Your question is not clear. R u going to do solvent effect or going to take UV for any one of solvent. If one means try CHCl3 or DCM.
Question
1 answer
I have been assembling a manuscript that reviews older (1920's to 1970's) data on benzene exposures and the composition of solvents and other materials that led to the reported benzene exposures.
One very interesting report on solvent composition was pulled from the USA OSHA benzene docket. The report title is "Solvents Analyzed at the ISGUM Industrial Health Labs". The samples are from factories in Istanbul, Ankara, Izmit, and Kirikkale Turkey. The samples results are all dated 1979 to 1972.
Do any of you know if this laboratory still exists? I'd like to know a bit more about it, to at least be able to describe the original source for the report in more detail.
Relevant answer
Answer
Turns out another try via a Google search gave the answer. İSGÜM - Occupational Health and Safety Center Turkey. İSGÜM was founded in 1968 as a sub-institution of Directorate General of Occupational Health and Safety in the constitution of Ministry of Labor and Social Security by the agreement between Turkish Government and ILO in the scope of International Programme for the Improvement of Working Conditions and Environment (PIACT). http://www.isgum.gov.tr/default1.aspx
Question
11 answers
The reaction is moisture sensitive, so no water. Until now I have been using organic solvents like oleylamine and DMF, but the concentration saturates at 0.1mM.
Any insights that could push this limit into the range of 1-10mM is more than welcome.
Relevant answer
Answer
The cosolvent is primarily intended as a modifier of the 'main' solvent properties. The ratio of cosolvent to solvent can be relatively small: possibly about 1:5 might be a reasonable figure.
Dmethyl sulfoxide (DMSO) seems promising as a possible cosolvent for use with glacial acetic acid. Possible complex compounds could be less stable than in DMSO alone, what may be favourable concerning the intended reaction. Also promising is pyridine, yet with similar problems to DMSO, being also prone to act as coordinating agent. Pyridine also dissolves PbCl2. Formic acid may perform worst than DMSO or pyridine, but complex compounds should not be a problem.
Question
2 answers
What is the best solvent for my research?
Relevant answer
Answer
thank you very much Dr. A. Lemos, Ph.D.
at the next time i hope you could help me to solve any problem on this my research topic.. :)
Question
12 answers
Can you suggest the organic solvent in which lornoxicam is fully or highly soluble?
Relevant answer
Answer
Soluble in 0.1N sodium hydroxide solution.
Soluble in DMSO and Methanol (Sparingly).
Many studies have been reported on solubility enhancement of lornoxicam. If you want to try solvents and strategies other than organic solvents, then you have options.
Question
14 answers
I am planning to do a reaction in the solvent free area. Because solvents may influence our solid catalyzer by absorbing on or solving it, the catalyzer which I will use is a clay type.
Relevant answer
Answer
If you are using the solid catalyst, then you have to consider some of the point below
1. Most of the active sites in the solid catalyst is situated in the bulk. Thus, you need to facilitate the reactants to access the active sites and after the reaction products being formed, you need to transport it out.
2. This the pore opening and surface area of you clay are important.
3. make sure the pore opening is large enough for your reactant penetrate in to access the active sites.
You should not have the fear of the solvent absorbing your catalysts. If the catalyst dissolves in solvent then it only turn the catalysis from heterogeneous to homogeneous.
The solvent need to have low affinity to the active sites, if not the solvent will poison the catalyst.
I
Question
4 answers
Organic solar cell
Relevant answer
Answer
Water is good choice for PEDOT:PSS complex but removal of its layers will also depend on the type of substrate material on which it is being deposited.
Question
3 answers
I have powdered hydroxyethyl starch (Sigma H6382) and want to make its solution.
Relevant answer
Answer
I'm not familiar with the process you want it for, but from what I've read on the internet, it looks like it is used intravenously, dissolved in 0.9% saline. So it should dissolve in water without too much problem. It apparently has a lower gelatinisation temperature than normal starch, so you might want to avoid heating it.
Question
5 answers
Both solvent in solute and solute in solvent?
Relevant answer
Answer
The term mutual diffusion was coined by Hartley and Crank (Trans. Faraday. Soc., 1949, 45, 801). Inter-diffusion ( Brown, J.Chem. Soc., Trans., 1918, 113, 559; Albright & Mills, J. Phys. Chem., 1965, 69, 3120) is an equivalent and interchangeable term.
In a two component system, one only needs a single diffusion coefficient to describe mixing due to a composition gradient. Generally experiments yield a value for the volume-fixed frame of reference (flows measured relative to the centre of volume of system, which moves due to the different densities of the solutions that are mixing).
In multicomponent systems, a matrix is required as the diffusion or flow of one component sets up counterflows of the others. For an n-component system, an (n-1)x(n-1) matrix is required. The elements of the matrix are related by the Onsager reciprocal relations, so in a ternary system, only 3 of the 4 matrix elements are independent.
The mutual diffusion coefficient needs to be distinguished from the self or intra-diffusion coefficients of the components in the mixture, which describe their thermal or "Brownian" motion. In an binary electrolyte solution there are three such self-diffusion coefficients, solvent, cation and anion.
In general there is no relation directly linking the self-diffusion and mutual diffusion coefficients, though there are many approximations in the literature.
Appropriate books are Cussler, Diffusion, CUP, 2009; Tyrrell and Harris, Diffusion in Liquids, Butterworths, 1984.
Question
1 answer
Separation techniques
Relevant answer
Answer
Fistly, we extracts with 80% MeOH and subsequently fractionate with Pet. Ether and Ethyl acetate
Question
7 answers
My experiment deals with the synthesis of the PNIPAM polymer in DMF. After the reaction, the solution is precipitated into chilled dry diethyl ether. I do not know what "chilled dry solvent" is, can anybody help me?
Relevant answer
Answer
Great, I'm happy it worked out well!
Cheers
Question
7 answers
Does anybody know the possibility of coagulating alkane thiol passivated gold nanoparticles in chlorinated solvents like chloroform, dichloroethane etc? Also let me know if there are any references for this.
Relevant answer
Answer
See if this helps Controlled UVC Light-Induced Fusion of Thiol-Passivated Gold Nanoparticles. Langmuir 2011, 27, 5234–5241
Question
3 answers
Explanation
Relevant answer
Answer
Why can't u try Toluene, dichloromethane, DMF or THF
Question
5 answers
I've tried using Isopropanol, butoxyethanol : butoxyetoxyethanol (6:4 weight) and DMF as the solvent to dissolve SD1, but they also dissolve PMMA. Any suggestions?
Relevant answer
Answer
They are also not compatible with PC. However, they will not harm polyamide.
Question
5 answers
I will be extracting using methanol as a solvent and I am trying to figure another way of removing methanol from my plant extracts except via a rotary evaporator
Relevant answer
Answer
Vacuum (reduced pressure) distillation: Use an aspirator,to make vacuum and a magnetic stirrer with heating.
Question
13 answers
, acetone, DCM, DMF, DMSO, ehthayl acetate, toluene, CCl4, water and THF. Can anyone tell me a solvent
Relevant answer
Answer
try to study the solubility at different temperature, if you get any prommising data you can try to analyze your sample by NMR that contain cell heater
Question
8 answers
I'd like to calculate relative energies for some molecules with taking a solvent into account. Reaction takes place in sulfuric acid, which is not included in the list of defined solvents in Gaussian. Could somebody recommend what to do in this case? Maybe someone did calculations in H2SO4 environment?
Relevant answer
Answer
Dr. Badohglu is correct. When defining a new solvent using Gaussian software, you need to know the values for the following parameters: (i) EPS - the static dielectric constant - you can generally find this number somewhere within the Gaussian manual... or from some other reputable source!, (ii) EPSINF - the optical (or dynamic) dielectric constant. This number is calculated by squaring the refractive index (n) of the solvent, (iii) RSOLV - The molecular radius of the solvent. I calculate this number using the Stearn-Eyring equation, and (iv) DENSITY - The density of the solvent. This number needs to be in units of particles/(Angstroms^3). Just find the density of the solvent in g/(cm^3) and convert it to particles/(Angstroms^3). As a test, For DMF, 0.944 g/(cm^3) = 0.0078 particles/(Angstroms^3). I hope this information helps. Good luck!
Question
9 answers
I usually isolate lipids from foodstuffs and biological samples using Folch´s method substituting Chloroform with Dichloromethane with excellent results. However recently some publications point out the possibility of using MTBE with similar results as that of Matyash et al. (see attachment).
I would like to know the lab experience of other researchers using this solvent in lipidomics. Thank you!.
Relevant answer
Answer
Dear Luis,
Generally, all solvent systems are appropriate for the extraction of predominant lipid classes with high recoveries. Matyash compared MTBE with the Folch method, others have compared the Folch and Bligh and Dyer methods (Iverson et al., Lipids, 2001, 36, 1283), and methanol based method with Folch method (Lofgren et al., J Lipid Res, 2012, 53, 1690) in the extraction of lipophilic compounds.
In my own experience, the challenge lies in the extraction of minor and less abundant lipid classes, and in this case each solvent system will be more suitable depending on the class of lipids you're interested in isolating. For instance, hexane based system will be particularly suitable for the extraction of FA, TAG, Cer and CE; using MTBE system will efficiently extract sphingolipids (SM, Cer, LacCer); whereas using the acidified Bligh and Dyer will extract polar lipid classes (LysoPC, LAA, CS and LacCer).
In case you're aiming to an exploratory analysis you can find some guidelines in (http://www.ncbi.nlm.nih.gov/pubmed/23670529) before implementing a routine analysis.
Hope this helps,
Question
8 answers
Solvent content of my protein crystal according to Mathews is 68% for 1 molecule and 38% for two molecules but after molecular replacement in Molrep I am getting only one chain in asymmetric unit. Phaser is also giving solution only when I use one molecule in input. How to validate this?
Relevant answer
Answer
Hi Nidhi, Mathews coefficient just helps to you ESTIMATE the number of protein and/or RNA(DNA) chains in the unit cell. But Molecular replacement gives the definitive answer. It is not that uncommon to have high solvent content in a crystal. Good luck with the refinement.
Question
18 answers
We want to dissolve polymers in suitable solvents and incorporate porous materials for some applications.
Relevant answer
Answer
ESTANE is soluble in THF or THF/MEK blends;
VITON(s) is soluble  in acetone and EtAc if uncured ; cured ones (in mechanical parts for example) only are swellable in this solvents
 PTFE is soluble in perfluorinated solvents at high temperatures :
Question
9 answers
Polymers.
Relevant answer
Answer
It depends on crosslinking degree, type of organic substituents (methyl or phenyl) and mol. weight (polymerization degree) as well. Sometimes the solvents swell but do not dissolve it, solubility in the abovementioned solvents strongly depends on the properties listed above.
Question
70 answers
Chitosan is a kind of a polymer.
Relevant answer
Answer
Chitosan can be dissolved in acidic sovents. You can use any of the two methods
1. Chitosan can be dissolve in the mixture of 0.1M Acetic acid and 0.2M NaCl (at Room temp., 12 Hours with stirring) ............OR...............
2. Chitosan can be dissolved in 0.1M acetic acid (at 60 degrees celcius ., 5 hrs with stirring)
Question
10 answers
Conductive silver paste is used in our electrochemical studies. To do further experiments, I need to get rid of this silver paste from my compound.
Relevant answer
Answer
I have used several silver ink. we clean most of them with Acetone "e.g: novacentrix silver, dupont silver", but some provider like Marchem are water based and most be clean with tape water and soap.Hope it help.
Question
5 answers
.
Relevant answer
Answer
DMSO, Water, and polyhydroxyl alcohols are the best. Formalin (at temperatures >80°C chemical reactions produce melamine – formaldehyde resins), hydroxymethyl derivatives of ketone and aliphatic compounds containing electronegative groups are other choices...
Question
6 answers
Non-protic solvents are normally used for hydride ion reactions, but not in thee above case .
Relevant answer
Answer
Among many reducing agents are LiAlH4 and NaBH4; the former being stronger because it can reduce a wide variety of compounds including carboxylic acids, esters, nitriles ,amides, aldehydes and ketones at room temperature while the latter reduces only aldehydes and ketones at room temperature.
As H (2.10) is more electronegative than Al (1.61), H carry a signifant negative charge and LiAlH4 reacts violently with protic solvents like H2O and ROH to form flammable H2.So we have to use inert/ anhydrous/ nonprotic solvents like R2O and THF.
NaBH4 reacts very slowly with protic solvents at room temperature because B (2.04) and H electronagativities are comparable .So reactions with NaBH4 can be easily conducted using protic solvent like ROH. However, NaBH4 decomposes with -COOH which need to be protected by forming its Na salts by reacting with NaOH .In this way only –CHO or -CO- groups are reduced while –COOH can be regenerated from its Na salt.
Question
1 answer
Seeking information on the physical and chemical properties of solvents.
Relevant answer
Answer
You can just measure it in the way described here:
Just keep in mind that the method is very simple and the accurancy might be not that good.
Question
1 answer
Acetonitrile in GAMESS.
I want to do DFT calculation including PCM model in Gamess, but I have problem to define that as a solvent.
As my best knowledge, there is many solvents in DMS table but I can't find any thing for acetonitrile.
Relevant answer
Answer
Why not try to use SMD model? It has parametrization for acetonitrile. An excerpt from REFS.DOC follows:
++++++++++++++++++++++++++
The SMD model gives an alternative set of such "CDS"
corrections, which are compatible with nuclear gradients:
see SMD=.TRUE. in $PCM. A more detailed description of SMD
is given in the paper cited below. The SMD solvent
parameters is described (as of 2010) in
This gives numerical parameters, all built into GAMESS, as
the various SOLX values, for SOLVNT=
ACETACID CLPROPAN PHOPH EGME E2PENTEN
ACETONE OCLTOLUE DPROAMIN MEACETAT PENTACET
ACETNTRL M-CRESOL DODECAN MEBNZATE PENTAMIN...
++++++++++++++++++++++++++
Question
7 answers
Role of solvent.
Relevant answer
Answer
In a solution the solvent is present in high concentration.Therefore the concentration of solvent is effectively a constant.Thus the solvent concentration terms do not come in to the rate expression.However the rate constant gets modified depending on the solvent.This is because of the formation of solvent cages.The solvent molecules arrange around the reacting molecules forming solvent cages.So the molecules undergo collisions with in these solvent cages.So the overall rate is affected by the solvent.
Question
1 answer
I want to check the organic solvent tolerance of a bacteria
Relevant answer
Answer
You mean to check the permeability of solvent across the membrane ...... Generally we take octanol water system for the study .... Need much more clarification
Question
13 answers
What can we use except D-limonene? It's basically an organic solvent, but the permeability is actually about the waxy layer (~5 nm) surrounding the vitelline membrane. Would acetone be right for this?
Relevant answer
Answer
Sure,
I usually permeabilize the embryos after fix it but I supposse that without fixing works too. After wash the embryos in PBT (PBS +0.5%Triton) I wash 1/2 PBT 1/2 Methanol one mitute or two, then retire half of the liquid and add more methanol. Finally I wash the embryos 20 minutes in 100% methanol.
I hope that it works for you!
Question
2 answers
While extracting the active chemical in ethylacetate the yield was very, very low, less than 100mg/liter. In many publications I saw there is on an average 500mg or more yield per liter of culture filtrate (actinomycete) processed. Is there any step not mentioned in the publications? Can anyone suggest how to get more yield from the culture filtrate?
Relevant answer
Answer
If your molecule lack polar groups it could remain adsorbed in the mycelium
Question
10 answers
Please suggest me a solvent in which I can dissolve EGCG? Is it soluble in water?
Relevant answer
Answer
@Vitor...instd of bt being polyphenol quercetin doesn't dissolve in water!
Question
2 answers
I want to isolate dioxins degrading bacteria from soil contaminated samples. would like to know the best solvent for dioxins during enrichment
Relevant answer
Answer
It all depends on what type is the soil. Depending on the nature of the sample in the extraction of dioxins often are used mixtures of polar and nonpolar liquids. Typical is also a fact, that the time-consuming Soxhlet extractions is often used. The enclosed text should help you.
Question
3 answers
I want to write a proposal about the role of solvent in the paint and coating technology, can anyone help me please?
Relevant answer
Answer
Well if you can speak german the most informative book about solvents is:
Hans Kittel Band 4, Lösemittel, Weichmacher und Additive
S. Hirzel Verlag, 2007
ISBN-13:9783777610146
More than 500 pages about solvents, softeners and additives for the paint industry.
But I must admit there is not too much literature about solvents for paints as it is something we just need for transporting the binder out of the can onto the the substrate and that has to leave the film after having done this job.
Very helpful for coatings technology is the
BASF Handbook: Basics of Coatings technology, from Athur Goldschmidt at Vincentz Network
ISBN 978-3-86630-903-6 also available as e-book
It is a very useful book, that still often use and that I recommend to every one, but it contains only 8 pages about solvents.
PMMA transparent gel?
Question
36 answers
In the Name of God. What solvent for PMMA form a transparent and water free gel? Please don't answer ethylene carbonate (EC) or butylene carbonate (BC). Because EC and BC are expensive solvents. I want cheaper and common solvent.
Relevant answer
Answer
Toluene.
Question
3 answers
Can anyone suggest a better solvent than acetone to remove AZ 5214 photoresist from a glass substrate-the portion that is not exposed to laser, plasma or temperature without affecting the surface functional group?
Relevant answer
Answer
You can use resist stripper. But check its usage is allowed in the laboratory.
Question
12 answers
Sometimes we use a huge amount of solvents for extracting our targeted molecules. Some solvents are so expensive and for this we recycle this solvent for further use to save our money. But one thing is the quality of the recycled/recovered solvents is a critical factor in controlling the quality of the resulting natural products in pure form.
Relevant answer
Answer
It all depends what are the impurities, Most "solid" will not get distilled. our biggest problem will be if you are dealing with mixtures of various solvents.
have a look at: Purification of Laboratory Chemicals from Perrin and Armarego
Question
8 answers
I used MeOH and water for extracting natural products from bacteria but active fraction did not misible in water methanol solvents for HPLC analysis. How can I prepare HPLC sample for for analysis? Is there any alterative solvents?
Relevant answer
Answer
Acetonitrile is aprotic, and should dissolve some non-polar analytes that MeOH will not. In the past, I have also used 50/50 tetrahydrofuran with either ethanol or acetonitrile for even less polar analytes.
Question
1 answer
I used MeOH and water for extracting natural products from bacteria but active fraction did not misible in water methanol solvents for HPLC analysis. How can I prepare HPLC sample for for analysis? Is there any alterative solvents?
Relevant answer
Answer
please indetfy the type of natural product ( alkalois, phenolics,glycosides/ macrolides or others) based on that you chose the solvent for extractions and HPLC
Question
2 answers
I want to use the silica solution in UV-Vis spectrophotometer
Relevant answer
Answer
Distilled Water.......
Question
6 answers
I have a marine organism. When I conducted cold extraction for it, I got crude extract for non-polar to polar solvents for around six different solvents. When I tried to dissolve these crude extracts in DMSO for anti-microbial activity, the crude extract for lower concentration (50mg/ml) was dissolved nicely, unlike 100mg/ml or 200mg/ml which did not dissolve properly. Instead, a whitish colored tissue degraded and a sort of foamy substance formed in the top layer and middle layer of DMSO with undissolved crude extract, and in the lower layer with the dissolved crude extract. It happened with acetone and ethyl acetate extract. Hexane got dissolved properly. Ethanol and methanol partially dissolved, where chloroform only got 20% dissolved. I tried for warm extraction using soxhlet. Unlike in cold and hot extraction using hexane crude, I got the same whitish colored tissue degraded foamy substance even without dissolving in DMSO. For other crude extracts only minimal amount of whitish colored tissue degraded foamy substance appeared. I still need to try with ethanol and methanol.
I am in desperately in need of your help. I have attached some photos.
Relevant answer
Answer
The whitish substance could be proteins. I would suggest you to not dissolve initially in DMSO. Try various solvents such as ethanol, methanol, diethylether, chloroform, dichloromethane. You can also try dissolving some in water. Once the antimicrobial test is successful, purify it and at the last step try dissolving in DMSO.