Methylenediamines intermediate

Butadiene is by far the most important monomer for synthetic rubber production. It can be polymerized to polybutadiene or copolymerized with styrene to styrene-butadiene rubber (SBR). Butadiene is an important intermediate for the synthesis of many chemicals such as hexa-methylenediamine and adipic acid. Both are monomers for producing nylon. Chloroprene is another butadiene derivative for the synthesis of neoprene rubber. 

Methylenediamines are readily synthesized from the reaction of secondary amines with formaldehyde. Many aliphatic amines are too basic for direct nitration without a chloride catalyst, and even then, nitrosamine formation can be a problem. Their conversion into intermediate methylenediamines before nitration is therefore a useful route to secondary nitramines. The success of these nitrolysis reactions is attributed to the inherent low basicity of the methylene-diamine nitrogens. 

Adiponitrile is an important intermediate for the manufacture of hexa-methylenediamine (Section 3.4), which, together with adipic acid, is used to produce nylon 6,6. Although adiponitrile is still largely produced from adipic acid, obtained by vapour phase oxidation of cyclohexane (Section 2.2), it is also manufactured from butadiene by DuPont on the basis of the process first patented in 1970 (Equations 24-26). Conversion is 99% with >90% selectivity to adiponitrile. 

In addition to the Ross-Schiessler process, utiliang P-CH2O and AN, the synthesis of RDX/ HMX mixts has also been reported starting with other small molecules (Ref 7), namely, methyl-amine nitrate methylenediamine dinitrate and nitramine (NH2NO2) in combination with CH2O. In these reactions, the intermediate formation of Hexamine or a cyclic analog, is not necessarily established... 

In Mannich reactions performed in basic media, the active aminomethylating species is less well defined. It may be a methylenediamine (9), a hydroxymethylamine (8), or an alkoxymethylamine (ROCH2NR2 ) (in alcoholic solvents). Aminomethylation in base-catalyzed Mannich reactions, as shown for cyclohexanone, is believed to occur by an 5n2 mechanism in which the enolate (13) displaces either NR2", 0H , or OR from one of the intermediates above (Scheme 2). 

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