Abstract Di(aminophenyl)methane having a high proportion of the o,p''isomer (10 to 60 percent) and a substantial proportion of the o, o''-isomer (5 to 25 percent) is obtained by reacting at least 3.5 moles of aniline with 1 mole of formaldehyde, separating the water of condensation from the resulting mixture of aniline and anilino-acetal, heating the anhydrous mixture to 125* C. to 205* C. and adding a proton source (aniline hydrochloride preferred). The mixture of di(aminophenyl)-methane isomers can be separated from the mixture of polyamines so obtained and phosgenated to give a mixture of the corresponding isomeric di(isocyanatophenyl)methanes which mixture is a storage stable liquid. Alternatively the mixture of polyamines can be phosgenated, without separation of the di(aminophenyl)-methane, to give the corresponding mixture of polymethylene polyphenyl polyisocyanates. The latter mixture gives polyurethane foams of much lighter color than those obtained using comparable mixtures produced by prior art procedures.
The process of claim 1 wherein the proton source is hydrogen chloride.
Claim 2
Dependent Claim
14 words
The process of claim 1 wherein the proton source is an aromatic amine hydrochloride.
Claim 3
Dependent Claim
12 words
The process of claim 3 wherein the proton source is aniline hydrochloride.
Claim 4
Dependent Claim
24 words
The process of claim 1 wherein the anhydrous aniline-formaldehyde condensation product is heated at 185* to 190* C. during addition of the proton source.
Claim 5
Dependent Claim
111 words
In a process for the preparation of di(aminophenyl)-methane wherein the p,p''-isomer content is from about 15 to about 85 percent by weight the o,p''-isomer content is from about 10 to about 60 percent by weight, and the o,o''-isomer content is from about 5 to about 25 percent by weight, based on total di(aminophenyl)-methane, the steps of: heating an anhydrous mixture of aniline and anilinoacetals, obtained by condensation of formaldehyde with excess aniline, to a temperature of about 125* C. to about 205* C. and adding thereto under anhydrous conditions a catalytic amount of a proton source selected from the class consisting of hydrogen halides and the salts thereof with aromatic amines.
Claim 6
Dependent Claim
12 words
The process of claim 6 wherein the proton source is hydrogen chloride.
Claim 7
Dependent Claim
14 words
The process of claim 6 wherein the proton source is an aromatic amine hydrochloride.
Claim 8
Dependent Claim
12 words
The process of claim 6 wherein the proton source is aniline hydrochloride.
Claim 9
Dependent Claim
25 words
The process of claim 6 where the reaction temperature is within the range of 185* to 190* C. during the addition of the proton source.