4,4 -diaminodiphenylmethane, reaction diisocyanates

It should be stressed that the viscosity changes during formation of polyurethanes even from bifiinctional compounds can be correlated with gelation most likely they are connected with the formation of a physical network then crosslinks arise from sufficiently strong specific interactions like hydrogen bonds [50]. An example of such a process is the reaction of macro (diisocyanate) with 3,3 -dichloro-4,4 -diaminodiphenylmethane [43]. 

The production of aniline is a major international business, carried on in the US, Europe and Asia, mainly for the conversion, by reaction with formaldehyde under acid-catalyzed conditions, into diaminodiphenylmethanes 9a, 9b and 9c, and then into isocyanates, mainly 4,4/-methylenebis(phenylisocyanate) (MDI, also known as 4,4 -methylene-di-paraphenylene isocyanate, 4,4 -diphenylmethane diisocyanate, methylene diphenylene diisocyanate and diisocyanato diphenyl methane) (9d), from which polyurethanes are produced. This accounts for well over 60% of total demand (Figure 1). Aniline is also used in bulk for the production of antioxidants and vulcanization accelerators for rubber. Some 15.5 million lbs. of cyclohexylamine are made each year mainly by catalytic hydrogenation of aniline. Half the demand is for use as a boiler water additive. Other major uses include in the manufacture of herbicides, plasticizers, emulsifying agents, dyes, dry-cleaning soaps, acid gas absorbents and, in Asia, cyclamate sweeteners. Apart from India, the use of aniline for dyestuff manufacture represents about 10% of demand. 

Diaminodiphenylmethane n (DDM, methyl-enediamine, MD). A silvery, crystalline material obtained by heating formaldehyde aniline with aniline hydrochloride and aniline. It is used as a curing agent for epoxy resins and as an intermediate in making diisocyanates for urethane elastomers and foams by reaction with phosgene. Possible occupational hazards in the use of DDM are toxic hepatitis and liver damage. 

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