Ochem Question

[Pinbear]

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Y'all know why add 2 mol of ammonia to cleave anhydride or acyl halide to produce amide?

Anhydride or acyl halide + 2 mol of ammonia ---> amide

 

[UCB05]

Don't quote me on this but I think it's just a matter of convenience. The substitution reaction is reversible, so to increase amide yield, you use an excess of ammonia to drive the reaction forward. With an acyl halide, you get a HX byproduct, which can react with some excess ammonia in solution to form NH4X for a total of two ammonias consumed in reaction. With an anhydride, the initial reaction froms an amide and a carboxylic acid. The carboxylic acid can then react with another molecule of ammonia to from an ammonium alkanoate, again for a total of two ammonias consumed. In both cases, the second ammonia is used in a subsequent reaction with the byproducts of amide formation.

 

[loveoforganic]

Yep, just acts as a proton sponge, which eliminates the strongly acidic conditions that make Amide hydrolysis occur

 

[RCT PC CRN]

One act as nucleophile to replace Cl or RCOO, other act as base to react with HCl or RCOOH to produce salt.