Sciencemadness Discussion Board - Alternative Solvents and New Solvents - General Discussion

Alternative Solvents and New Solvents - General Discussion

BromicAcid - 7-1-2008 at 16:59

The focus of this thread has been retconned

but that won’t make a difference if you are newcomer so read on.

This thread is to focus on solvents that we hardly hear about. Sure, we are all familiar with pyridine, benzene, dichloromethane, toluene, ethanol, etc. But what about benzotrifluoride? You could look it up and see the structure, but where to go from there? It’s a chemical that is being used most recently as a solvent, specifically as a replacement for dichloromethane in reactions. The point is that it is not one of our ‘traditional’ solvents. It’s a relative newcomer to the field, the first major paper on it’s use being published J. Org. Chem in 1997.

What I am hoping this topic does is expose some of us to what new solvents are being used in academia and in industry. What solvents are being used and pushed as replacements for our traditional solvents, and what are some of their properties? This is not meant to be something comprehensive, more of an open invitation to get some dialogue going between our members.

This sort of information is important in allowing us to transfer from newer work being done with these new solvents to our traditional solvents we use and also to do the opposite. The interesting thing being that although in the areas of organometallic catalysis and ligand chemistry the molecules are becoming increasingly complex and difficult to prepare, in many of these solvents they are already existing molecules only recently thought of as solvents and some of them have relatively simple structures, the types of things an aptly equipped at home chemist might be able to tackle.

So, feel free to name off some solvents being pushed as replacements for solvents of old. Solvents that are ‘new’ all together and just interesting news on the solvent front (if you’ll pardon the pun).

I’ll kick things off:

Cyclopentyl Methyl Ether C5H11OCH3

I was reading about this today in the newest issue of Aldrichimica Acta (Vol 40, No 4). Supposedly it can be used as a replacement for many of the ethers, MTBE, THF, Dioxane and others. It is resistant for forming peroxides, is stable to acids and bases, it does form an azeotrope with water, works well for organometallic reactions. The ACS has an article on this compound however it is for members only and the link only brings you to an outline with slightly more information. It can be prepared from reacting cyclopropanol with a methylating agent or by reacting cyclopropene with methanol under pressure.

2-Methyltetrahydrofuran C4H7OCH3

What really makes this one earn its name as a green solvent is that it is renewable, it is made from corn cobs and farm refuse. Additionally it has a higher boiling point (allowing for stronger reflux) and lower melting point so it can be used at lower temps than THF. This compound as well as the one above are covered in a bulletin that Aldrich released concerning green solvents, a copy can be found on their site here.

Dimethyl and Diethyl Carbonate

The two of these compounds are fairly similar. The organic carbonates have a reasonably low toxicity compared to some of the other common solvents. Additionally Dimethyl carbonate has been receiving quite a bit of interest as an alternative to dimethyl sulfate, and methyl iodide as a methylating agent.

Benzotrifluoride C6H5CF3

Information on the developing solvent characteristics of this compound was obtained from:

J. Org. Chem.; (Communication); 1997; 62(3)

Basically the authors determined that it behaved similarly to dichloromethane and took it upon themselves to run a number of reactions in the solvent that were traditionally run in DCM with either easier reaction or equivalent reaction. The solvent has a higher boiling point which lends to higher refluxes and additionally there were some other notes on toxicity.

[Edited on 1/8/2008 by BromicAcid]

UnintentionalChaos - 7-1-2008 at 18:24

Catalytic Hydrogenation of http://en.wikipedia.org/wiki/Furfural yields 2-methyltetrahydrofuran....that also looks like it has the potential to be used as a "green" plastic

D-limonene is also available from citrus peel oil on a massive scale and finds it's way into many cleaning products...It can also be converted into poly-limonenecarbonate, which has similar properties to polystyrene

microcosmicus - 7-1-2008 at 20:21

I don't know if it would count as green, but what about DMSO?
Certainly, it's proponents make a big to-do about it being
natural. At any rate, it arises as a byproduct of the process
of making paper --- not the greenest activity, but at least
one does not have to make extra damage to the environment
to synthesize it.

By the way, since you raised this post, Bromic Acid, I would
like to than you for posting the stuff about electrolysis in
DMSO on your homepage. Inspired by your efforts, I ordered
a bottle of the stuff which just arrived. As time permits, I
plan to fiddle around with seeing what I can and can't
deposit in that medium.

As for the issue of good or bad for the environment, I suppose
"the dose makes the poison" applies here as well.

chemrox - 7-1-2008 at 23:26

http://www.chemsoc.org/ExemplarChem/entries/2004/bristol_vic...

http://www.rsc.org/ej/gc/2005/b418069k.pdf

are a couple of good places to read about them

woelen - 7-1-2008 at 23:40

I understood that DMSO indeed is not very toxic, and some people use it to treat skin rashes. It is said, however, that DMSO is a great transport mechanism for other toxic compounds. E.g. aqueous solutions of metal salts only penetrate the skin and can enter the body very slowly, while DMSO solutions of the same salts quickly pass through the skin and the salt easily reaches lower-lying parts of the body.

To my opinion, every solvent, which is a byproduct of another commonly used and important process, may be considered green. You get the solvent at no additional environmental cost.

I do not think that non-toxic solvents must be called 'green'. If making a non-toxic chemical requires a lot of energy and natural resources, then its use may seem 'green', but the total environmental impact still is high.

In this entire discussion we must clearly distinguish between two kinds of 'green':
1) Green from the point of view of total environmental impact from production to waste
2) Green from the point of view of the person, who uses the material.

JohnWW - 8-1-2008 at 00:34

Quote:

Originally posted by chemrox
http://www.rsc.org/ej/gc/2005/b418069k.pdf

Someone with a subscription to the RSC's Journals, please download this item, and post it here. I could not download it - access denied.

there you go :)

stoichiometric_steve - 8-1-2008 at 03:29

i re-posted it in: References » Wanted References and Needed Translations (3)

[Edited on 8-1-2008 by stoichiometric_steve]

kmno4 - 8-1-2008 at 03:44

Quote:

Originally posted by woelen
.........

Exactly.
Whatever you would say - H2O is the "greenest" solvent.
This thread is about everything and about nothing. Lists, synthesis, properities ... ? Encyclopedias, articles, books.....

Sauron - 8-1-2008 at 04:15

2-methylTHF is also known as sylvan and is nothing new. I would expect the peroxide forming properties of this compound to be similar to those of THF, e.g., worse than those of Et2O.

MTBE has only earned a place in the Hall of Shame because the EPA and DOE upgefucked and approved it for use as a gasoline additive. It was never an environmental problem previously, mostly because it had few uses.

Dioxan (1,4-dioxan) IS a problem because it is a carcinogen.

When Aldrich is "pushing" products like this, look to the bottom line. "Green" solvents at what premium? Don't be a sucker for a current fad like this. The only reason to pay a premium for a solvent is if that solvent has real advantages that justify the expense. Otherwise let the chemical industry make and sell these supposedly environmentally benign solvents CHEAPER than the usual solvents, and promote their use that way, then I might believe them.

Too often in the history of industrial chemistry the rationale for many many products is that it is a waste product from other processes. The industry wants to turn its garbage into $$$ amd we get saddled with the downstream products, many of which in the fullness of time have turned out to be harmful. Best to avoid playing that game at all.

chromium - 8-1-2008 at 05:26

Butyl acetate is said to be less harmfull than most solvents. Ethanol is probably as harmelss as solvent can ever be (excluding water of course). Diethyl ether can not be very harmfull as it has even been used for human consumption. Saturated hydrocarbons are rather harmless. Propylene carbonate is said to be of very low toxicity and seems to have some interesting uses too.

There are quite few of rather harmless solvents among most common. It would be interesteng to know why exactly are some exotic solvents called as "green" and how well these claims are founded. I would like very much to do my experiments with harmless and "green" chemicals but like Sauron, i am sceptical.

[Edited on 8-1-2008 by chromium]

Sauron - 8-1-2008 at 07:19

There's no h in butyl acetate.

microcosmicus - 8-1-2008 at 09:17

Quote:

Diethyl ether can not be very harmful as it has even been used for human consumption.

The only such use of which I am aware was as an anaesthetic in the
nineteenth centrury. However, I would hardly take the practice of those
times as a guide, otherwise I would be tasting chromium salts and
engaging in similarly questionable practises. The following website

http://www.anaesthetized.com/images/ether.html

lists the following effects

Unwanted effects of exposure to ether can include a cough, sore throat, painful red eyes, a headache, drowsiness, laboured breathing and nausea. Vomiting is quite common.

so, while it may not be downright toxic like H2S of HCN, I don't care
to be ingesting it either. I suspect it is not much different from other
common organic solvents in this respect.

Again, I think it is important to think quantitatively and put things in
perspective --- just how much chemical is being used in the lab as
opposed to other places? Personally, I am not too worried about
the the potential for environmental damage from metal salts and
solvents in my experiments especially since I do them on a micro-scale
(hence the pen name). Rather, I focus my efforts on being green on
things like what solvents I use to clean floors and windows or what
agents I use to unclog drains .

I assume it is similar on a larger scale in industry. While I can see the
impact of a company using a greener solvent in the large-scale
production of plastic or drugs, I doubt that going green in the lab
is going to anywhere nearly as significant an effect.

[Edited on 8-1-2008 by microcosmicus]

not_important - 8-1-2008 at 09:25

Quote:

...Diethyl ether can not be very harmfull as it has even been used for human consumption.

That's a bit faulty logic. Consider chloroform, onced in used in toothpaste
http://www.oehha.ca.gov/air/chronic_rels/pdf/67663.pdf

Older examples of toxic materials used in foods include the Victorian era colouring of candy and fancy baked goods using arsenic based pigments.

Quote:

Saturated hydrocarbons are rather harmless. ...

Not quite true, for example hexane:

http://www.jns.dergisi.org/text.php3?id=174

http://www.atsdr.cdc.gov/toxprofiles/tp113-c2.pdf

this is chronic exposure, at levels approaching and exceeding a part per thousand; hopefully one is careful enough to avoid such levels of exposure for extended periods in the lab. This may be an example of varying sensitivities in the population, from genetic differences in metabolism of alkanes and metabolic products. There's also evidence that acetone and other simple ketones may increase the toxic effects, but then acetone is common in the lab.

chromium - 8-1-2008 at 10:45

My logic is very simple - if there are lot of people who were exposed to that chemical much more than i am - and it still did not ruin their life then there is no good reason to think that it ruins my life.

Logic of modern toxicity studies does not seem that reliable for assessing actual risks. There is usually no way to tell if those 1% or 3% or 10% who got serious health problems were not simply more sensitive than most of us are or they even might be those who have just bad hygiene or who got these problems with help of some other substances, diseases, heredity etc.

That said, when doing my chemistry i am always very carefull. I do most of work in microscale and fumes are always vented out but i think that quite remarkable part of modern toxicity and cancerogenicty fears are just result of misuse of statistics or of confusing general health and hapiness with lack of symptoms.This is just my point of view no need to agree with it.

Returning to human consumption of diethyl ether - in former soviet union it was sometimes used instead of vodka in small quantities. There is lot of folk tales about drinking ether and eating some hot food afterwards. I am sure this was more harmfull than drinking vodka or moonshine but it was not by far as destructive as regular use of inhalants or hard drugs.

[Edited on 8-1-2008 by chromium]

microcosmicus - 8-1-2008 at 11:11

Now that you mention it, I also do remember coming across stories of
people using vodka during the prohibition of the roaring twenties.

Ozone - 8-1-2008 at 12:06

Quote:

Originally posted by kmno4

Quote:

Originally posted by woelen
.........

Exactly.
Whatever you would say - H2O is the "greenest" solvent.

Cyclodextrins can be used as very nice "green" phase transfer catalysts. They can enable a fairly wide variety of chemistry to occur in aqueous matrices.

For example, a benzene ring will fit into the hydrophobic cavity of b-CD and Nap will fit into y-CD.

Cheers,

O3

MagicJigPipe - 8-1-2008 at 15:57

Yes, from what I've read, people used to drink ether based drinks during prohibition and even before and after.

Honestly, I just don't consider hexane very toxic. I mean, no more so than gasoline which consists of a significant amount of hexane.

I mean, yeah, you should take the average precautions that you would with any hydrocarbon solvent. To me, it's just a common sense issue. Just keep your exposure as low as you can. Sounds simple enough to me. Now carcinogens, mutagens, teratogens etc... are different, of course.

Polverone - 8-1-2008 at 16:25

"Green" materials and processes are particularly advantageous to amateur chemists, in my opinion, for a number of reasons. Green processes usually employ reaction conditions which are easier to reach without specialized apparatus. They're also tailored to waste minimization, which also translates to removal of unneeded reagents and sometimes easier workup too (see examples from J. Chem. Ed.).

Low-toxicity solvents and reagents may be more expensive, but they can reduce shipping hazards, thus shipping price. When it comes to use also, low-toxicity is good, because many amateurs work without truly professional fume hoods or waste disposal services. Less hazardous chemicals are also less likely to be withheld from sale to the public by suppliers.

pantone159 - 8-1-2008 at 17:15

I was told once that hexane is significantly more toxic than pentane, and for this reason I bought pentane at the time instead of hexane. The problem here with that, is that ambient (outside) temperatures often enough exceed the BP of pentane (36.1 C), so the volatility is a problem.

BromicAcid - 8-1-2008 at 17:23

Originally this topic covered Green Solvents. But what I was really getting at was solvents that are being proposed as alternatives to traditional solvents. The usual trend though for this is that these alternative solvents are comparable or better in terms of their characteristics, and are usually safer, Greener. Hence my initial mindset on Green solvents.

Additionally this was not meant to be an all-inclusive topic (as in everything will be covered in great detail) but instead an open invitation to contribute whatever anyone felt so long as it was useful or relevant.

I wanted to see examples of solvents that are being explored and pushed that maybe we haven’t all seen before. I mean, when was the last time you flipped through your issue of CE news and saw an add depicting an old man in a rocking chair with the caption, “Do you remember when a solvent was a solvent? At Carbon Tet we remember, and we still make our carbon tetrachloride the old fashioned way, by photochlorination of methane, using all natural pure as rain sunlight. That’s right, our brand of carbon tetrachloride is all natural, the way nature intended, so when you’re looking for a solvent, a Cadillac of solvents, think Carbon Tet, your children will thank you.” Actually that was somewhat pointless, sorry, but I can’t bring myself to delete it.

Regardless, what are some of these new solvents? What are they used for and what are they replacing and what are their properties. And if things are simple enough how can we go about making them? Surprisingly most of these solvents seem to be fairly simple compounds especially compared to what you might see in a cutting-edge ligand or organometallic catalyst.

Additionally this kind of topic can be used in reverse, suppose you see an article in the newest issue of and organic chemistry journal that relies on Benzotrifluoride and you go, “What the hell?” this thread would hopefully then have the post that says Benzotrifluoride is being used in place of dichloromethane due to its higher boiling point which allows for a stronger reflux.

Anyway, the focus was not to be just Green solvents though there is a lot of research being done in the area, but also solvents that are being toted as alternatives to traditional solvents. Relative newcomers into the field that really haven’t had their limits tested in academia and just interesting solvents in general. Again, it’s broad but there is more to work with here, more freedom and we can leave the stigma of wondering what’s worse for us or what’s worse for the planet and just focus on the chemistry at hand people.

chemrox - 8-1-2008 at 21:01

Quote:

Originally posted by BromicAcid
The focus of this thread has been retconned

Translation please!

saturated HC's tox assertions-> PTC quests

chemrox - 8-1-2008 at 21:14

Quote:

Originally posted by not_important
[this is chronic exposure, at levels approaching and exceeding a part per thousand;

@Not_important .. there are few things that aren't toxic with chronic exposure above trivial levels .. I miss the old phisohex product .. anyway, today when confronted with a new agent I look for information dating from about 1950 and the decade after .. my childhood chemistry set had an experminet including an H2S generator but one of you is sure to say this explains some things...

But to return to the topic, I like acetonitrile whenever it can be used.. lots of solubility ..washes away readily (where is away, anyway?) and has been mentioned, ionic liquids where applicable. I have a PTC question for another thread. What makes an appropriate PTC? Why choose a tetraalkylhaloammonium salt over a PEG for example?

Cheers,
CRX

[Edited on 8-1-2008 by chemrox]

BromicAcid - 8-1-2008 at 21:15

Retcon From Wiki-

Quote:

Retroactive continuity or retcon is the deliberate changing of previously established facts in a work of serial fiction. The change itself is referred to as a "retcon", and the act of writing and publishing a retcon is called "retconning".

http://en.wikipedia.org/wiki/Retcon

franklyn - 8-1-2008 at 23:36

Quote:

Originally posted by Sauron
The only reason to pay a premium for a solvent is if that solvent has real advantages
that justify the expense.

@ BromicAcid
For amateur chemistry anything not OTC is just wishful. Specialty solvents only have
real world application in industrial scale process chemistry, and are in such instances
specifically engineered for that application and purpose. Sure, flourocarbons have
useful properties, but at a dollar a gram are beyond the budget of a hobbyist, or one
may try to synthesize these by the halex reaction. Chemistry performed in a reaction
vessel using non obvious solvation such as liquid CO2 would be more cost effective.
In practice the only reason to resort to a solvent is for the exclusion of water and
obviating hydrolysis, or for rendering polymers and resinous materials. A single solvent
on it's own has limited and specific utility, the blending of solvents to achieve desired
properties is a science in itself and in practice very much an art.
_______________

Increasingly rare because it's an ozone depleting chlorocarbon - trichloroethane is, was
very user friendly and nontoxic even less so than dichloromethane. Get it before it's gone !
http://www.retcoalloy.com/?page=shop/browse&category_id=...
.

[Edited on 9-1-2008 by franklyn]

Sauron - 9-1-2008 at 02:05

Ethyl ether (Et2O) was a popular tipple among medical students in the 19th and well into the 20th centuries and may still be in some places.

Usually referred to as going on an ether jag.

Probably not done in concert with cigarette smoking, at least not more than once.

This existed or exists in parallel to the diversion of high proof ethanol by students for making Purple Passion punch, etc.

That can be problematic because of the potential confusion between potale USP ethanol, and denatured ethanol, or even absolute ethanol, which contains traces of the benzene and acetone used to break the azeotrope (in many cases.) The consequences of consuming such nonpotables grades of ethanol can be, well, unfortunate.

DrP - 9-1-2008 at 02:19

One of my suppliers last year sent me some samples of an alternative solvent for general white spirits. Their suggested uses were as a cleaning solvent safer than white white spirit and as a possible solvent for a coating system. The trade name was STEPOSOL and was listed as a METHYL SOYATE & ETHYL LACTATE BLEND. The MSDS said it was a methyl ester/ethyl lactate. It seemed to be an adequate like for like replacement for cleaning purposes - I haven't tried any real chemistry with it though.

PS - it is made from Soya beans apparently. Thus the greenery.

[Edited on by DrP]

MagicJigPipe - 9-1-2008 at 14:14

Speaking of that Sauron, I've always wondered if there's ever been an incident with cigarette smoking and pure grain alcohol. As in a severly burned mouth and/or esophagus.

Back on topic.

In my opinion, a lot of the compounds that we already use are more "green" than people think. For example, acetone (correct me if I'm wrong) and methanol break down relatively easily into harmless products in the environment.

Now, of course, aromatics and saturated HCs are different.

Sauron - 9-1-2008 at 15:27

Under no circumstances would I regard methanol as a benign substance. It is too toxic and too readily absorbed for us poor humans to regard it as green. Its environmental fate is formic acid, and salts thereof, via formaldehyde.

Not all aromatic hydrocarbons are all that nasty. Some are and some aren't. There is nothing about aromaticity that is, in and of itself, hazardous.

microcosmicus - 9-1-2008 at 15:44

And, of course, the production of acteone by destructive distillation of
calcium acetate is about as green as manufacturing process come ---
cook vinegar and chalk, you even get to recycle the chalk. The same
could be said for the destructive distillation of wood to produce MeOH.
Also, Weizmann's industrial fermentation process for acetone sounds
like it ought to be green (or whatever color the microbes come in).

Hmm . . . maybe the shtick with the old dood in the rocking chair isn't
so bad an idea after all. I could see environmentally conscious consumers
going for paint thinners made the old way from wood and vinegar.

microcosmicus - 9-1-2008 at 16:06

Acetone, on the other hand, seems more benign, at least according
to eco-usa.net ( http://www.eco-usa.net/toxics/acetone.shtml ) :

Quote:

Acetone enters the air, water, and soil as a result of natural processes and human activities. Acetone occurs naturally in plants, trees, volcanic gases, and forest fires. People and animals breathe out acetone produced from the natural breakdown of body fat. Acetone is also released during its manufacture and use, in exhaust from automobiles, and from tobacco smoke, landfills, and certain kinds of burning waste materials. The levels of acetone in soil increase mainly because of acetone-containing wastes being buried in landfills. Acetone is present as a gas in air. Some acetone in air is lost when it reacts with sunlight and other chemicals. Rain and snow also remove small amounts of acetone from the atmosphere and, in the process, deposit it on land and water. About half the acetone in a typical atmosphere at any time will be lost in 22 days. Microbes (minute life forms) in water remove some acetone from water. Some acetone in water will evaporate into air. About half the acetone in a stream will be removed from water in less than a day. Fish do not store acetone from water in their bodies. Microbes in soil remove part of the acetone in soil. Some is lost from soil by evaporation. Acetone molecules do not bind tightly to soil. Rainwater and melted snow dissolve acetone and carry it deeper into the soil to groundwater.

According to the Dow product safety assessment, most acetone in the
environment comes from natural sources:

http://www.dow.com/productsafety/finder/acetone.htm

The EPA removed acetone from the list of bad chemicals, pointing out that the
substitutes were worse! (Sounds like justification for Sauron's skepticism.)

http://www.epa.gov/fedrgstr/EPA-TRI/1995/June/Day-16/pr-15.h...

BromicAcid - 9-1-2008 at 16:53

Again, I've tried to shift the subject from the Green aspect of things simply because it can cause this sort of 'back and fourth' of what's good and what's bad. But on the subject of acetone, I have worked in places with bacterial waste water management and occasionally we would have to 'feed the bugs' which meant pumping 275 Gal of acetone into the sewer which made its way to the microbiological processing area and caused a proliferation of those beautiful sewage eating microbes.

@ franklyn-
If you honestly think that anything not 'OTC' in terms of a solvent is not realistic for the chemist at home I would think you're missing the whole point of chemistry at home or your intentions/aspirations are entirely different than my own. Granted I didn't do it much but I managed to run reactions in the nitrobenzene that I made (definitely not OTC). Not the most elaborate of choices but I was working on making diethyl carbonate for a solvent as well, though I never perfected it I could produce usable quantities of ethylene carbonate which I just never converted to the next step of things. Besides, what you consider OTC is of course different than what others in other countries call OTC and what others have access to despite it not being OTC in their area, perhaps they have run across a bottle of a particular solvent.

Nevertheless, I find this topic interesting. I've said it before, I have a solvent fetish, I think they are some of the most interesting aspects of any chemical reaction and for that reason alone I think it's interesting to learn about some of these newer solvents being pushed or new takes on older solvents. If only to see where the field is heading but also for the other benefits that I have mentioned before.

chloric1 - 9-1-2008 at 16:54

Quote:

Originally posted by pantone159
I was told once that hexane is significantly more toxic than pentane, and for this reason I bought pentane at the time instead of hexane. The problem here with that, is that ambient (outside) temperatures often enough exceed the BP of pentane (36.1 C), so the volatility is a problem.

@pantone-IIRC, Hydrocarbons with even number carbons are significantly more toxic than odd number hydrocarbons based on how this products are metabolized. For the life of me, I wish I could recall the source. Also, I had the same volatility problem with DCM(BP 34°) and I live much more north than you(Indianapolis) where summer temperatures typically reach or exceed 35°C less than 10 times a year! The outside temperature only needs to approach BP as many sheds, storage facilities, garages, can easily exceed reported temperatures. Then again many liquids evaporate easily even 10 or 15°C below there boiling point.

@everone else-Big chemical corporations pushing "green" solvents reminds me of what happend nearly 20 years ago. Sometime during the late 1980's Dow's Patent rights on freons where about to expire. At the same time the media reported new "scientific" findings that freons where eating holes in the ozone layer. With all the new legislation that
passed in the 1990's you could only use R-134 and its cogeners which costed much more. And don't forget after 1996 a large number of chlorinated solvents where determind as "hazardous" to ozone. Hence you could find 1,1,1-Trichloroethane for the bargain of $300 per gallon. I can't wait until the UN gets it's carbon tax!

franklyn - 21-2-2010 at 00:21

A related thread here _
http://www.sciencemadness.org/talk/viewthread.php?tid=10529

.

Mush - 9-5-2020 at 12:39

Cyclopentyl methyl ether
https://www.manufacturingchemist.com/news/article_page/A_new...

Dioxolane

Attachment: BASF_Brochure_Dioxolane.pdf (592kB)
This file has been downloaded 289 times

[Edited on 9-5-2020 by Mush]

clearly_not_atara - 9-5-2020 at 21:54

You bored lately, Mush? You've revived a lot of threads.

njl - 10-5-2020 at 18:01

This is a topic I'm very interested in. Whenever I get to thinking about solvents I feel like I'm at a slumber party talking about cute boys

.
I want something immiscible with water, forming an azeotrope like toluene, as available as ethanol, not flammable, and low boiling. Maybe I should do some reading about solvent design...

Side note: I had to use DMSO in pH sensitive coupling and the smell was UNREAL. I've worked with smelly stuff before. I've had my fair share of phosgene puffs to the face. But the smell of satanic rotten cabbage/garlic fermented in a butthole that persisted for HOURS has been the worst.

fusso - 10-5-2020 at 19:36

Quote: Originally posted by njl

I want something immiscible with water, forming an azeotrope like toluene, as available as ethanol, not flammable, and low boiling.

DCM?

clearly_not_atara - 10-5-2020 at 20:43

Depending on the nucleophilicity of your reactants 1,2-dichloroethane might be suitable. The azeotrope is 13 C deep.

mackolol - 10-5-2020 at 23:34

Quote: Originally posted by njl

This is a topic I'm very interested in. Whenever I get to thinking about solvents I feel like I'm at a slumber party talking about cute boys

It's because dimethyl sulfide, which is dissolved in trace amounts in DMSO is evolved while heating.

Quote: Originally posted by mackolol

When I worked with trace amounts evolved from slightly impure DMSO it smelled like really bad sulfur SHIT.
Good way for neutralisation of Me2S is to put exhaust pipe to dilute solution of hypochlorite. Now for me it works very well and doesn't produce any odor.

B.D.E - 12-5-2020 at 02:13

Quote: Originally posted by pantone159

I was told once that hexane is significantly more toxic than pentane, and for this reason I bought pentane at the time instead of hexane. The problem here with that, is that ambient (outside) temperatures often enough exceed the BP of pentane (36.1 C), so the volatility is a problem.

I use n-heptane instead. it has its own pros and cons:
pros:
*allegedly less toxic than n-hexane.
*not very volatile
neutral:
*high b.p(y(~98.4C)
cons:
*b.p is very close to that of water(somewhat problematic in extractions).
(it is of course phase separating from water. so in general it's not that big of a deal).

[Edited on 12-5-2020 by B.D.E]

njl - 12-5-2020 at 03:09

@fusso I have about 400 ml of dcm left, it's pretty hard for me to get but very precious

G-Coupled - 12-5-2020 at 04:52

Quote: Originally posted by njl

@fusso I have about 400 ml of dcm left, it's pretty hard for me to get but very precious

DCM is one of the most useful solvents IME - are there any solvents/reagents that seem easier than 'normal' for you to acquire where you are, as a matter of interest?

njl - 12-5-2020 at 05:32

I agree dcm is great. I bought a liter for pretty cheap but now my only way is to distill from paint thinner which yields about 300 ml for 20 USD and a couple hours of work. I can get drain cleaner sulfuric acid so ethers may be an option, but I'm not big on straight chain ethers just because of peroxide/flammability issues in storage. I have used dioxane a lot but that's soluble in water. To answer your question, Acetone, "Denatured alcohol" (~60/40 ethanol/methanol), "Mineral spirits" (I'm guessing medium length alkanes), and I think I've seen naptha but I've never looked into it.

DavidJR - 13-5-2020 at 02:40

Quote: Originally posted by njl

I agree dcm is great. I bought a liter for pretty cheap but now my only way is to distill from paint thinner which yields about 300 ml for 20 USD and a couple hours of work. I can get drain cleaner sulfuric acid so ethers may be an option, but I'm not big on straight chain ethers just because of peroxide/flammability issues in storage. I have used dioxane a lot but that's soluble in water. To answer your question, Acetone, "Denatured alcohol" (~60/40 ethanol/methanol), "Mineral spirits" (I'm guessing medium length alkanes), and I think I've seen naptha but I've never looked into it.

Dioxane is carcinogenic, and also can't be used for preparing Grignard reagents (Schlenk equilibrium). So it's not a replacement. THF is much safer than diethyl ether, so it is my preferred ethereal solvent. It still has issues with peroxides.

I've heard about 2-MeTHF which is renewable and has some technical advantages over THF, but I haven't found anywhere selling it at a reasonable price. It still forms peroxides.

CPME (cyclopentyl methyl ether) is even more interesting to me as it apparently doesn't form peroxides, is water immiscible, and works well for organometallic chem as well as liquid-liquid extraction and azeotropic drying. But again, I can't find it anywhere at prices that aren't obscene.