CPC C07C 263/06 (2013.01) [C07C 269/04 (2013.01)] | 20 Claims |
1. Process for preparing a diisocyanate of the formula (A)
where R is selected from the group consisting of alkyl, aryl, and combinations thereof, comprising the following process steps in the indicated order:
1) Providing an intermediate of the formula (B) with a process using lysine and urea
where R and each R′ are independently selected from the group consisting of alkyl, aryl, and combinations thereof; and
2) thermolytic cleavage of the intermediate of the formula (B),
thereby affording the diisocyanate of the formula (A); and
wherein the process further includes one of the following series of process steps prior to process step 1):
either a.1) providing of lysine;
a.2) reacting the lysine with urea to form a urea adduct of the formula (C)
and
a.3) reacting the urea adduct of the formula (C) with an alcohol to form the intermediate of the formula (B);
or b.1) providing of lysine;
b.2) reacting the lysine with a base to form a lysine salt of the formula (Z);
where X is a counterion;
b.3) reacting the lysine salt of the formula (Z) with urea to form a urea salt of the formula (Y);
where X is a counterion;
b.4) reacting the urea salt of the formula (Y) with an alcohol to form a carbamate of the formula (X)
where each R′ is independently selected from the group consisting of alkyl, aryl, and combinations thereof, and X is a counterion;
b.5) reacting the carbamate of the formula (X) with an acid to form the carboxylic acid of the formula (W)
where each R′ is independently selected from the group consisting of alkyl, aryl, and combinations thereof; and
b.6) reacting the carboxylic acid of the formula (W) with an alcohol to form the intermediate of the formula (B);
or c.1) providing of lysine;
c.2) reacting the lysine with a base to form a lysine salt of the formula (Z);
where X is a counterion;
c.3) reacting the lysine salt of the formula (Z) with urea to form a urea salt of the formula (Y);
where X is a counterion;
c.4) reacting the urea salt of the formula (Y) with an alcohol to form the intermediate of the formula (B).
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