Sulfur chlorides reaction with, phosgene

Here, a key factor in selecting the appropriate method is the environmental impact of the by-products. Both reactions release hydrogen chloride, which can easily be removed by a scrubber filled with aqueous sodium hydroxide. The scrubber also decomposes traces of phosgene. In contrast to the reaction with phosgene, which liberates harmless carbon dioxide as a second by-product, thionyl chloride releases gaseous sulfur dioxide, which significantly burdens the environment, and cannot be removed by simple methods. 

Phosgene reacts with a multitude of nitrogen, oxygen, sulfur, and carbon centers. Reaction with primary alkyl and aryl amines yield carbamoyl chlorides which are readily dehydrohalogenated to isocyanates. Secondary amines also form carbamoyl chlorides. 

Carbonyl dichloride (phosgene) phosphoryl chloride/ phosphorus trichloride thiophosgene, thionyl chloride/ sulfur dichloride and cyanuric chloride react with carbodiimides to give the expected chloroformamidine derivatives. In the reaction of carbodiimides with two equivalents of carbonyl chloride N,N -disubstituted chloroformamidine N-carbonyl chlorides 703 are obtained. 

Violent reaction with benzoyl chloride combined with KOH, Bt2, barium carbonate, CS2, Cr(OCl)2, Cu, Pb, HNO3, BaCOs, H2SO4, hot water, (CH3)2S04, dibromomalononitrile, sulfuric acid. Incompatible with acids, ammonium chloride + trichloroacetonitrile, phosgene, cyanuric chloride, 2,5-dinitro-3-methylbenzoic acid + oleum, trifiuroroacryloyl chloride. Reacts with heavy metals (e.g., brass, copper, lead) to form dangerously explosive heavy metal azides, a particular problem in laboratory equipment and drain traps. When heated to decomposition it emits very toxic fumes of NOx and Na20. See also AZIDES. 

N-Methyl-N-methoxycarbamoyl chloride made by phos-genation of methoxy methyl amine hydrochloride is a very useful intermediate for the synthesis of N-methoxy ureas herbicides. However, we found the method to be unsatisfactory for the production on a large scale, because of rather low yields and also of technical difficulties. To overcome these problems, we developed a new procedure based on the reaction of phosgene with methoxy methyl amine sulfate as depicted in scheme 124. Sulfuric acid formed is easily removed by decantation (Ref. 177). 

Owing to the greater nucleophilic character of sulfur relative to oxygen, reaction of 1,3-disubstituted thioureas with phosgene usually occurs at the sulfur atom, to give high yields of chloroformamidinium chlorides [2083a, 2087] ... 

---