How will you convert methyl bromide to dimethylamine?

Question

Christian Anderson · Accepted Answer

#2H_3C-Br + NH_4Br + 3N(CH_2CH_3)_3rarr(H_3C)_2NH + 3[HBr*N(CH_2CH)_3]#

The industrial process uses ammonia, methanol, heat, and pressure. Perhaps there would be a laboratory synthesis along these lines. I assume you are answering a question rather than performing an actual synthesis.

#NH_3 + 2CH_3OH rarr HN(CH_3)_2 + 2H_2O#

However, it is not possible to replicate this reaction in a lab.

In the first reaction, each #N-C# bond is formed with the elimination of triethylamine hydrobromide. Hence we need 2 equiv of #Et_3N# for the #2xxC-N# bond formation, and a third equiv to give the ammonia, the free base. The trithylamine operates as a non-nucleophilic base here to sop up the hydrogen bromide produced. These days, we have non-nucleophilic bases such as #"DBU"#, and #"DABCO"#; these are more basic than the amine, and are a lot less pfaff to use.

Paisley Boney · Answer

undefined To convert methyl bromide to dimethylamine, you can follow a multi-step synthesis. The synthesis typically involves nucleophilic substitution reactions. Here's one possible synthetic route:

1. React methyl bromide (CH3Br) with sodium hydroxide (NaOH) to form methanol (CH3OH) and sodium bromide (NaBr) via an SN2 reaction:

CH3Br + NaOH → CH3OH + NaBr

2. React methanol with ammonia (NH3) in the presence of a catalyst (such as aluminum oxide) to form dimethylamine (CH3NHCH3) and water:

2 CH3OH + NH3 → (CH3)2NH + 2 H2O

This reaction proceeds via a condensation reaction.

Overall, the conversion of methyl bromide to dimethylamine involves two steps: first, converting methyl bromide to methanol, and then converting methanol to dimethylamine through reaction with ammonia.