Sciencemadness Discussion Board

which kind of solvents can replace benzene?

stoneflower - 9-10-2006 at 20:12

Now i am working on the synthesis of vanillin ex-catechol-guaicol process, and use benzene to extract the vanillin. because of its toxicity, i want to change the solvents, but i don't know which kind of solvents are suitable for me?

not_important - 9-10-2006 at 21:09

Toluene or xylene are the easiest to get that are close, for simple extraction. Still toxic, but much less so than benzene and most solvents are somewhat toxic.

stoneflower - 9-10-2006 at 22:24

However, according to The Extraction Solvents in Food Regulations 1993(88/344/EEC), toluene or xylenen is also not permitted in the extraction of vanillin if vanillin will be applied in foods. Anything else would i try? Combined solvents?

not_important - 9-10-2006 at 22:48

That regulation is long after benzene was no longer used, else it would be in there as well.

As for alternatives, depends on what you are extracting from and all that. Other good solvents for vanillin include CS2, CCl4, CHCl3, ether, pyridine, glacial acetic acid, and the lower alcohols.

If you're looking at manufacturing vanillin for food purposes, then you're talking large scale industrial stuff, not home hobbist. Use supercritical CO2 + dimethyl ether.

vovan78 - 10-10-2006 at 00:00

Don't use CS2, CCl4, pyridine, glacial acetic acid, and the lower alcohols :o
CS2, CCl4, pyridine are toxic; glacial acetic acid, and the lower alcohols are soluble in water.
The best would be ether or CH2Cl2
Good luck :D
Quote:
Originally posted by not_important
That regulation is long after benzene was no longer used, else it would be in there as well.

As for alternatives, depends on what you are extracting from and all that. Other good solvents for vanillin include CS2, CCl4, CHCl3, ether, pyridine, glacial acetic acid, and the lower alcohols.

If you're looking at manufacturing vanillin for food purposes, then you're talking large scale industrial stuff, not home hobbist. Use supercritical CO2 + dimethyl ether.

stoneflower - 10-10-2006 at 00:49

vovan78:
which kind of ether do you think is suitable instead of benzene? diethyl ether? methyl-tert-butylether? or others? Thank you very much for your kindness and ideas.

vovan78 - 10-10-2006 at 01:09

It's up to you, both are good. Methyl-tert-butylether smells a little and boils higher but it’s chipper than diethyl ether.

not_important - 10-10-2006 at 19:13

Given the recent fuss over MTBE in fuel getting into ground water, I would think twice about using it with food products. It will be cheaper for awhile as manufactures try to move enough to keep plants open.

vovan78 - 10-10-2006 at 21:47

stoneflower:

You can also use EtOAc; it doesn't form peroxides as ether, not toxic and easy degrade environmentally

not_important - 10-10-2006 at 22:10

Quote:
Originally posted by vovan78
stoneflower:

You can also use EtOAc; it doesn't form peroxides as ether, not toxic and easy degrade environmentally


This is why I mentioned that the reaction mix is imporant, one common method is the Reimer-Tieman reaction, this takes place in a strongly alkaline solution which would chop esters right up. You could nuetralise the reaction mix, but that adds to cost and it looks as if he's taking commericial production, else the Food Regulations would not be of concern.

vovan78 - 11-10-2006 at 00:52

not_important:

Of course CS2 and pyridine is much better
as you sad :D

not_important - 11-10-2006 at 21:34

Better than ester in base. The real point is that the original question was #$%^& lazy, as it left out many important bits of information such as exactly which method of adding the CHO was used, and that it was intended for food use which puts some restrictions on what can be used and implies a larger scale than home experimenter. If the asker is so lazy that can't properly frame a question, or answer U2U, then I'm going to be lazy as well and let them figure which to pick out of a list.