Imines, Enamines, Oximes, and Hydrazones

Write down the structures of the imines formed in the following reactions, and assign /Z stereochemistry to the carbon-nitrogen double bonds. It is reasonable to assume that the less sterically hindered isomer will be formed. 

Notice that in (b), the acetal is unreactive and stable to the reaction conditions (a) Ph 

In Chapter 9, we used the reagent hexamethylenetetramine, 14.24, as an alternative for ammonia in nucleophilic substitutions to prepare amines. This reagent is prepared by condensation of ammonia and formaldehyde. Draw out the fundamental reactions that are necessary to build this caged structure. When the nitrogen has substituted an alkyl halide, the product is converted to the amine by acid hydrolysis. Draw out the key steps in this process. 

In forming the reagent, the key reactions are nucleophilic addition of the amine to formaldehyde, formation of an imine or iminium salt, followed by attack of the ammonia on the carbon nitrogen 

When the nitrogen has been alkylated, and the intermediate is subjected to acid-catalyzed hydrolysis, then the process goes into reverse  

---