Goal: I'm an old man and that's why my picture might lay on it's side. Also, I'm a pharmacologist, computational chemist and neurologist, so I probably shouldn't be messing with synthetic chemistry. But this one seems simple. Carboxylic acid + SOCl2 = respective acyl halide. I've always wondered about the following. Equimolar neat SOCl2 and carboxylic acid, or excess SOCl2, and if excess, approximately how much (in molar ratios)? Many sincere thanks to all. I know, a dumb question. I've always used 2 SOCl2 to 1 acid, or more, but things haven't always gone right. Maybe for another reason. Thanks again.
Dear Dr Jones, I usually use an excess of SoCl2 to obtain the interest compounds and I take 2-3 equivalents of SOCl2 and it seems to work. However, I never try to isolate the corresponding compound due to its great reactivity. After, it depends of your initial compound and its functions because SOCl2 is very aggressive. Thus in sometimes we work with only 1-1.2 equivalents.
So many 'thanks,' Gilles Degotte. Yes, so you rotovap the unreacted SOCl2 and proceed with subsequent steps? Since some of my rotovaps are not in a hood I use a NaOH trap (20%) to catch the HCL and the SO2 so it is not a nuisance. Acyl chlorides generally have lower mp's than corresponding acids, and so far all my acyl halides have been liquids at RT. By the way, my practice has been precisely, by the book, identical to that you describe; 1.2 to 3 equivalents, but sometimes I get a mess I don't understand. Must be something else. Best Regards, Gary
Yes, I employ the acyl halides to form amide bond mostly. But my compounds are quite simple thus, most times the raw mixture is "clean". However, even the easiest reaction could lead to a surprisingly complex mixture. Best regards, Gilles.
Amides too. R is often complex, secondary alcohols, aromatic systems. Enjoy life, it offers so much, especially chemistry. Again, many thanks. Gary.
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