From: patrizio.pan-2002@libero.it   
      
   On Wednesday, August 23, 2017 at 3:41:30 PM UTC+2, ppati...@gmail.com wrote:   
   > On Sunday, 2 March 2003 03:53:46 UTC+5:30, Rob  wrote:   
   > > Anyone recommend a good alternative to pyridine as a reaction solvent?   
   > > The pyridine in the reaction I have is used to mop up HCl from reaction of   
   > > an acid chloride with polyvinyl alcohol.   
   > >   
   > > Thanks.   
   > >   
   > > Rob.   
   >   
   > Dear Rob   
   >   
   > You may take reaction in dichloromethane & triethylamine Mixture.   
      
   Good advice. In general, tertiary amines (R3N) work well in that job for   
   (1) they are all basic (capturing HCl) and (2) normally incapable of   
   undergoing acylation or similar electrophylic reactions like sulfonation   
   etc.   
   They are nucleophylic, and good ones also, but the reversible adduct they   
   initially form with electrophylic species (acyl chloride), i.e.   
   R'CO(-)Cl-N(+)R3, is not capable (if temp is not raised enough) of   
   eliminating HCl through a beta-H in their R groups (if present).   
   This leaves room for the nucleophyle of interest to react with the acyl   
   chloride (or the adduct, products will be the same).   
   So, to possibly avoid such complications, it is reasonable to choose an   
   amine not possessing beta-hydrogens.   
   To this end pyridine is optimally suited. The cited dimethyl aniline is   
   also good, though less resistant to an oxidative attack (if any) in the   
   aromatic ring.   
   In this respect N-methyl imidazole is better.   
   Trimethylamine has the only inconvenient that it is gaseous.   
   If the chosen amine has beta-hydrogens and the temperature has to be high   
   it is not advisable to use an excess of it: the part of it in excess acts   
   as a base to the said adduct favoring HCl elimination as a side reaction.   
      
   > Thanks   
      
   regards   
   Angelo   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)