Halogenated acetylenes acetylene chloride

See Halogenated Acetylenes under H s Iron Acetylide (Ferrous Acetylide) [Eisen (II)-acetylenid, in Ger], FeCjj solid, stable in the air or w at RT decompd by HCl with evoln of CjHa. Was prepd by Durand on treating CaCj with ferrous chloride Refs l)Beil 1,[220] 2)J.F. Durand, CR... 

Acetylene Black. See under Carbon Blacks Acetylene Chloride or Chloroethyne See under Halogenated Acetylenes... 

A series of acetylenic acids has been made from the corresponding acetylenic chlorides by way of the cyanides in over-all yields of 52-84%. Few halo acids have been made by this method because of the reactivity of the halogen atom e.g., hydrogen chloride is removed from 7-chloro-... 

Chemical Properties of Acetylene.—Acetylene and other substances which contain two carbon atoms joined by a triple bond, show in their chemical behavior a high state of unsaturation. Acetylene does not react with chlorine in the dark, but in diffused daylight addition of the halogen takes place, and a dichloride, C2H2CI2, and a tetrachloride, C2H2CI4, are formed. If the acetylene has not been carefully purified, the reaction often takes place with explosive violence and carbon and hydrogen chloride are formed. When the gas is passed into bromine the chief product of the reaction is acetylene tetrabromide —... 

Acetylene reacts with fluorine with explosive violence. Reactions with other halogens, chlorine, bromine, and iodine are violent, too. Acetylene chloride, which is formed from addition reaction with chlorine, explodes spontaneously. It forms unstable acetylides with metals such as copper,... 

Vlayl fluoride [75-02-5] (VF) (fluoroethene) is a colorless gas at ambient conditions. It was first prepared by reaction of l,l-difluoro-2-bromoethane [359-07-9] with ziac (1). Most approaches to vinyl fluoride synthesis have employed reactions of acetylene [74-86-2] with hydrogen fluoride (HF) either directly (2—5) or utilizing catalysts (3,6—10). Other routes have iavolved ethylene [74-85-1] and HF (11), pyrolysis of 1,1-difluoroethane [624-72-6] (12,13) and fluorochloroethanes (14—18), reaction of 1,1-difluoroethane with acetylene (19,20), and halogen exchange of vinyl chloride [75-01-4] with HF (21—23). Physical properties of vinyl fluoride are given ia Table 1. 

Halogenation and dehalogenation are catalyzed by substances that exist in more than one valence state and are able to donate and accept halogens freely. Silver and copper hahdes are used for gas-phase reactions, and ferric chloride commonly for hquid phase. Hydrochlorination (the absoration of HCl) is promoted by BiCb or SbCl3 and hydrofluorination by sodium fluoride or chromia catalysts that form fluorides under reaction conditions. Mercuric chloride promotes addition of HCl to acetylene to make vinyl chloride. Oxychlori-nation in the Stauffer process for vinyl chloride from ethylene is catalyzed by CuCL with some KCl to retard its vaporization. 

A much faster reaction for bromides than chlorides usually suggests attack on halogen, since bromine is more readily attacked by nucleophilic phosphorus. However, for phenyl acetylenes (82 = Ph) these rates... 

Mo and W hexacarbonyls, Mo(CO)6 and W(CO)6, alone do not induce polymerization of acetylenic compounds. However, UV irradiation toward these catalysts in the presence of halogenated compounds can form active species for polymerization of various substituted acetylenes. Carbon tetrachloride, CCI4, when used as the solvent for the polymerization, plays a very important role for the formation of active species, and thus cannot be replaced by toluene that is often used for metal chloride-based catalysts. Although these metal carbonyl-type catalysts are less active compared to the metal halide-based counterparts, they can provide high MW polymers. It is a great advantage that the metal carbonyl catalysts are very stable under air and thus handling is much easier. 

Metal-Halogen Compounds. Mercuric salts react readily with acetylenes, forming various products, depending upon the salt and reaction conditions. Mercuric chloride appears to undergo a clean insertion reaction with acetylene, giving as-2-chlorovinylmercuric chloride in the vapor phase (72, 73). 

Thus, exposure to any of these enzyme inducers concurrent with or after exposure to diazinon may result in accelerated bioactivation to the more potent anticholinesterase diazoxon. The extent of toxicity mediated by this phenomenon is dependent on how fast diazoxon is hydrolyzed to less toxic metabolites, a process that is also accelerated by the enzyme induction. Similarly, concurrent exposure to diazinon and MFO enzyme-inhibiting substances (e.g., carbon monoxide ethylisocyanide SKF 525A, halogenated alkanes, such as CC14 alkenes, such as vinyl chloride and allelic and acetylenic derivatives) may increase the toxicity of diazinon by decreasing the rate of the hydrolytic dealkylation and hydrolysis of both parent diazinon and activated diazinon (diazoxon) (Williams and Burson 1985). The balance between activation and detoxification determines the biological significance of these chemical interactions with diazinon. 

Although acetylene still is used in a number of organic syntheses on an industrial scale, its use on a high-tonnage basis has diminished because of the lower cost of other starting materials, such as ethylene and propylene. Acetylene has been widely used in the production of halogen derivatives, acrylonitrile, acetaldehyde, and vinyl chloride. Within recent years, producers of acrylonitrile switched to propylene as a starting material. 

Modena and co-workers (5) have also reported that cis-B-arenesulfonylvinyl chlorides (J4) undergo nucleophilic substitution of the halogen by methoxide ion by way of an E2 trans-elimination to an acetylene derivative (15) followed by a trans-addition to yield the cis-product 16. 

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