By venksin on Saturday, October 11, 2003 - 04:50 am:

Hi,

Could anybody suggest a method for analysis of an acid chloride (such as benzoyl chloride) by HPLC. Is derivatisation essential

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By Anonymous on Saturday, October 11, 2003 - 12:26 pm:

Venksin: It is a very labile compound. No chance in reversed-phase due to the use of aqueous mobile phases. In normal phase, I expect it to react with silica or with residual silanols on those packings that are derivatized.
The best and simplest way is a derivatization, with any amine, followed by reversed-phase.

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By venksin on Monday, October 13, 2003 - 02:49 am:

Thanks for the info. But how would you ensure complete derivatisation. Since the compound (the benzoyl chloride) is not stable on exposure, there are chances for the acid impurity to be present. Will it also get derivatised, or acid will remain free

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By Anonymous on Monday, October 13, 2003 - 12:25 pm:

Well, maybe you want to just analyse the acid

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By Chris Pohl on Tuesday, October 14, 2003 - 12:42 pm:

Venskin:

Relative to your question about the viability of directly performing an essay on an acid chloride: as mentioned above, you could well have problems with such an essay in the presence of an aqueous mobile phase although hydrolysis in the absence of a catalyst is not all that rapid so you might be able to get away with it in an unbuffered eluent system. It seems to me that you should also be able to make an ester with high enough yield to be able to perform the assay on the ester. For example, react the acid chloride with methanol under conditions suitable for quantitative conversion to the methyl ester.

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By venksin on Monday, October 20, 2003 - 08:59 pm:

Hi

On the derivatisation of acid chloride, of several methods tried we were more comfortable with a morpholine derivative (basically an amine derivative). The derivative will be formed in the presence of a strong base such as KOH. The acid was remaining free and thus could be estimated. Thanks for all suggestions