Saganism - 5-1-2013 at 20:04
To begin, this is in fact, entirely theoretical. I'm here to question the formation of dangerous peroxides during rxn. If one is to use acetone as a
co solvent this poses certain obvious risks, but I'm inclined to ask, is peroxide formation of the acetone avoidable? I've read only a single
article(the only I could find) in which there was a safer method, but I'm unsure of its credibility although I'm thinking it'd be alright. I'd like to
hear some opinions on the differences of the two as well as possible alternatives to acetone as a co solvent in an un buffered oxidation.
The buffered method is simply described as follows;
To a soln of the propenyl compound is added some sodium bicarbonate, and the performic acid is added dropwise. That's the essential jist of what's
methodically happening. What gets me is why would someone add the performic acid in drop wise to the propenyl instead of vice versa?
By vice versa I mean adding the propenyl drop wise to a performic solution in the flask
Thanks, Sagan.
[Edited on 6-1-2013 by Saganism]
turd - 6-1-2013 at 11:04
Your posting is not very coherent. This is not a good way to present a question. Apparently you talk about at least two methods but then expand on
only one (the "buffered" method). Is that the one with acetone and/or the "better" one? To establish a basis for discussion you should provide
references (preferably in the scientific literature) and structure your thoughts. No stream of consciousness, please!
Anyway, since I am sympathetic to your cause, I will try to answer what I think are your questions on the basis of the "buffered peracid oxidation"
that I am aware of:
Q1: The buffered peracid oxidation is a two phase reaction: There is the aqueous phase containing H2O2, a carboxylic acid (or its salt) and NaHCO3
(which is at the beginning not fully dissolved, making this actually a three phase reaction). Then you have the organic phase containing the
propenylbenzene. The idea is that the peracid is extracted from the aqueous phase into the organic phase and that the whole thing is not too strongly
acidic. So in this case adding acetone seems like a terrible idea: it is miscible with water and the organic solvent, thus worsening phase separation.
Q2: You want mild reaction conditions, that's why you slowly add the peracid to the substrate, not vice-versa. Doh.
Q3: The buffered peracid route works well with substrates that are not too acid sensitive. Yields are satisfactory given the sensitivity and
elusiveness of the product and it can be reproduced in an amateur setting. The trick is to thoroughly remove any acid before distillation and to
operate under a good vacuum.
HTH
Saganism - 7-1-2013 at 10:59
Yes, I am aware I was rather vague. My apologies. Thanks for the answers though.