Manufacturing Process
The N,N'-dibenzyl-N,N'-bis-[2-(3',4'-dihydroxyphenyl)-2-oxoethyl]-
hexamethylene-diamine dichlorohydrate-monohydrate used as the starting
material was prepared as follows: 2 mols of chloroaceto pyrocatechin were
dissolved in 2,000 cc of acetone and heated to boiling with 2 mols of N,N'-
dibenzylhexamethylene-diamine for 12 hours, almost the theoretical quantity
of N,N'-dibenzylhexamethylene-diamine dichlorohydrate being precipitated and
removed by suction after cooling. Excess HCl was added to the filtrate,
approximately 66% of the theoretically possible quantity of crude
dichlorohydrate of the N,N'-dibenzyl-N,N'-bis-[2-(3',4'-dihydroxyphenyl)-2-oxoethyll-hexamethylene-diamine being precipitated. The product was cleaned
by recrystallization from water with the addition of animal charcoal. After
drying the substance contained water of crystallization at ambient
temperature, MP 206° to 209.5°C.
Five grams of N,N'-dibenzyl-N,N'-bis[2-(3',4'-dihydroxyphenyl)-2-oxoethyl]-
hexamethylenediamine dichlorohydrate as a monohydrate were hydrogenated
under considerable agitation by means of 2.0 grams of 10% palladium-carbon,
with hydrogen in a mixture of 270 cc of methanol and 50 cc of water at 45°C
and normal pressure. After about 4 hours the theoretical quantity of hydrogen
(4 mols of hydrogen per 1 mol of substance) was absorbed for the splitting off
of the two benzyl radicals and the reduction of the two carbonyl groups to
carbinol groups, and the hydrogenation came to a stop.
After separation of the catalyst the product was concentrated until dry, the
residue was triturated with acetone, the resulting crystallizate was removed
by suction and washed with acetone. The yield of N,N'-bis-2-(3',4'-
dihydroxyphenyl)-2-hydroxyethyll-hexamethylene-diamine dichlorohydrate was
3.3 grams, i.e., 92% of the theoretical value. A quantity of 2.8 grams having
a melting point of 197.5° to 198°C was obtained by precipitation from a
mixture of methanol-ether.
Free N,N'-bis-[2-(3',4'-dihydroxyphenyl)-2-hydroxyethyl]-hexamethylenediamine can be separated from these salts by the addition of the equivalent
quantity of caustic alkali solution. It has a melting point of 162° to 165°C and
contains half a mol of water of crystallization.
N,N'-bis-[2-(3',4'-dihydroxyphenyl)-2-hydroxyethyl]-hexamethylenediaminesulfate (MP 222° to 228°C) can be obtained by reacting the base with
the equivalent quantity of sulfuric acid in an alcohol solution, followed by
concentration and precipitation from water-alcohol solution.
