Alkylation and The Hofmann Elimination

This is a nucleophilic substitution reaction with the amine acting as a nucleophile. 

The elimination of a quarternsry ammonium salt usually follows an E2 mechanism requiring a strong base. The quaternary alkyl halide, typically an ammonium iodide, is converted to a quaternary ammonium hydroxide using silver oxide. 

Heating the quarternary ammonium hydroxide results in the Hofmann elimination to form an alkene. 

Notice that the LEAST stable alkene is the major product in the Hofmann elimination, called the Hofmann product. 

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