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There are two general methods for preparing "thiourethane" collectors .
1. Haloalkane esterification method The base material of the "thiourethane" type collector is yellow, and the xanthate is esterified and reacted with a lower alkylamine to obtain a product easily. The reaction formula is as follows:
S
15-30 ° C /
MOH+CS 2 +ROH—————→ROC—S—M+H 2 O
0.5 hours
S S
/ 25-70 ° C /
ROC—S—M+CH 3 Cl—————→ROC—S—CH 3 +MCl
0.5 hours
S S
/ 15—50°C /
ROC—S—CH 3 +R′NH 2 ———————→ROC—NHR′+CH3SH
Oily
The molar ratio of the raw material formula is:
CS 2: NOH: RCH: RCl : R'NH 2 = 1: 135: 4.0: 1.01: 1.01 wherein M is an alkali metal ion, R, R'- group. Between 15 and 30 ° C, the reaction is carried out by fatty alcohol, caustic and carbon disulfide for 30 minutes (this step is actually the manufacture of xanthate), and the resulting mixture is reacted with chloroalkane at 25-70 ° C for 30 minutes, at 15- The alkylamine was introduced at 50 ° C and the reactants were separated to give an oily product. This is the general method for preparing "thiourethane" type collectors.
2. Monochloroacetate esterification Another method of preparing a "thiourethane" type collector is esterification with monochloroacetic acid. The reaction formula is as follows;
2ClCH 2 COOH+Na 2 CO 3 →2ClCH 2 COONa+H 2 O+CO 2
ROCSSM+ClCH 2 COONa→ROCSSCH 2 COONa+MCl
ROCSSCH 2 COONa+R'NH 2 →ROCSNHR'+HSCH 2 COONa
First neutralize the aqueous solution of monochloroacetic acid with sodium carbonate to pH=8, add the xanthate and stir it, leave it overnight, add the aqueous solution of alkylamine, and then overnight, acidify with acetic acid, then extract the product with diethyl ether to separate it from thioglycolic acid and steam. The ether was removed to obtain a "thiourethane" type collector.
3. A new method for the synthesis of "thiourethane" is directly synthesized by xanthate and alkylamine catalyzed by soluble nickel or palladium salts:
S S
/ Catalyst / R'
ROC—SNa+R'NH 2 —————→ROC—N < + NaHS
60°~90°C H
This eliminates the intermediate reaction with the halide and increases the yield, and the catalyst used can be recovered.