Group 13 sulfides hydrogen cyanide

Compounds with active hydrogen add to the carbonyl group of acetone, often followed by the condensation of another molecule of the addend or loss of water. Hydrogen sulfide forms hexamethyl-l,3,5-trithiane probably through the transitory intermediate thioacetone which readily trimerizes. Hydrogen cyanide forms acetone cyanohydrin [75-86-5] (CH2)2C(OH)CN, which is further processed to methacrylates. Ammonia and hydrogen cyanide give (CH2)2C(NH2)CN [19355-69-2] ix.orn. 6<55i the widely used polymerization initiator, azobisisobutyronitrile [78-67-1] is made (4). 

It is apparent that a new synthetic methodology, preferably catalytic, is needed for the synthesis of this important class of 2-(perfinoroalkyl)ethane thiols. In this context, a variety of catalysts was examined to determine if they wonld catalyze the hydrogenolysis of 2-(perfinorohexyl)ethane thiocyanate. In the conrse of this study, much to our surprise, it was discovered that a carbon supported Pd-Sn would catalyze the reaction. It is known that palladium and other group Vtll metal catalysts are poisoned by the product thiol, traces of hydrogen sulfide byproduct, and the hydrogen cyanide co-prodnct (6), but our observations are that this catalyst is surprisingly robust in the reaction medium. 

The thiol was obtained in >98% yield with trace amounts of the disulfide at 175°C and 700 psig H2 reactor pressnre in 1.5 honrs at a 900 1 substrate catalyst molar ratio. As discussed above, it is known that palladinm and other groups 8 to 10 metal catalysts are poisoned by the prodnct thiol, traces of hydrogen sulfide byproduct, and hydrogen cyanide coprodnct (6), bnt it is surprising that this catalyst is so robnst The effects of solvents, temperature, pressure, catalyst, and recycle will be discnssed. The characterization of the catalyst by various techniques will help to explain some of these observations. 

Ion exchange, in which cation and/or anion resins are used to replace undesirable anionic species in liquid solutions with nonhazardous ions. For example, cation-exchange resins may contain nonhazardous, mobile, positive ions (e g., sodium, hydrogen) which are attached to immobile acid groups (e.g., sulfonic or carboxylic). Similarly, anion-exchange resins may include nonhazardous, mobile, negative ions (e.g., hydroxyl or chloride) attached to immobile basic ions (e.g., amine). These resins can be used to eliminate various species from wastewater, such as dissolved metals, sulfides, cyanides, amines, phenols, and halides. 

Addition of hydrogen sulfide and thiols is qualitatively similar to reaction with alcohols in that there are two stages, formation of hemithioacetal (or hemithio-ketal) followed by acid-catalyzed elimination of the hydroxy group and substitution of a second —SR (Equations 8.47 and 8.48). The transformation has been studied less extensively than hydration and acetal formation, and relatively little information on mechanism is available. The initial addition appears to be specific base-catalyzed, an observation that implies that RS is the species that adds. The situation is thus similar to cyanide addition. General acid catalysis has, however, been found at pH 1 to 2 for addition of weakly acidic alkyl thiols, and the reaction rate as a function of pH has a minimum and rises both on the... 

The sulfonation reaction is reversible and benzenesulfonic acid may be desulfonated by treatment with dilute acid at 150 °C. The group can be displaced by fusion of its salt with sodamide to give the corresponding amine, with sodium hydroxide to give the phenol, sodium cyanide to give the nitrile, and potassium hydrogen sulfide to give the benzenethiol (Scheme 5.10). 

Additions of the Michael type of nucleophiles to the carbon-carbon double bond of thiete 1,1-dioxides to give 3-substituted thietane 1,1-dioxides occur readily. The addition of hydrogen has been discussed in Section A. Nucleophiles include cyanide, the anion of nitroethane, the lithium salt of r-butyl o-tolyl sulfone, dimethylamine, cyclohexylamine, ethoxide, and hydrogen sulfide. The reaction is exemplified by the synthesis of 278. Additions to 3-chloro-2H-thiete 1,1-dioxide most likely proceed by an addition-elimination mechanism an example is shown for the addition of the anion of dimethylmalonate to give 279. The replacement of a 3-morpholinyl group by a 3-A methyl-A-phenylamino group in thiete 1,1-dioxide is another example of addition-elimination. An addition of ethoxide with elimination of p-nitrophenyl anion may occur with 268 (Ar = / -N02C6H4). " Addition of bromine via N-bromo-succinimide to the double bond of 4-phenyl-2H-thiete 1,1-dioxide occurs only in 1.5% yield. ... 

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