Monovinyl -acetylene

The original commercial production was from acetylene through monovinyl-acetylene [689-97-4] ... 

Polychloroprene rubber (CR) is the most popular and versatile of the elastomers used in adhesives. In the early 1920s, Dr. Nieuwland of the University of Notre Dame synthesized divinyl acetylene from acetylene using copper(l) chloride as catalyst. A few years later, Du Pont scientists joined Dr. Nieuwland s research and prepared monovinyl acetylene, from which, by controlled reaction with hydrochloric acid, the chloroprene monomer (2-chloro-l, 3-butadiene) was obtained. Upon polymerization of chloroprene a rubber-like polymer was obtained. In 1932 it was commercialized under the tradename DuPrene which was changed to Neoprene by DuPont de Nemours in 1936. 

Chemistry of polychloroprene rubber. Polychloroprene elastomers are produced by free-radical emulsion polymerization of the 2-chloro-1,3-butadiene monomer. The monomer is prepared by either addition of hydrogen chloride to monovinyl acetylene or by the vapour phase chlorination of butadiene at 290-300°C. This latter process was developed in 1960 and produces a mixture of 3,4-dichlorobut-l-ene and 1,4-dichlorobut-2-ene, which has to be dehydrochlorinated with alkali to produce chloroprene. 

GR-A Government Rubber—Acrylonitrile GR-I Government Rubber—Isobutylene GR-M Government Rubber—Monovinyl acetylene GR-P Government Rubber—Polysulphide GR-S Government Rubber—Styrene... 

Syntheses of Dienes. The original process for preparing monovinyl-acetylene from acetylene is still used as the first step in the manufacture of 2-chlorobutadiene. Monovinlyacetylene is then reacted with hydrogen chloride to form the 2-chlorobutadiene according to the process described by Carothers. The two steps are illustrated as follows ... 

Poly(chloroprene) was one of the first synthetic elastomers. It came on the market in 1931, and was developed at the Du Pont factory as part of their search for elastomers for special areas of application. The industrial synthesis of the monomer became possible when Nieuwland discovered mono vinyl acetylene. Today, chloroprene is produced from monovinyl acetylene C4H4, butadiene butene C4H8, or butane C4Hio-... 

Wide-bore fused silica column capillary GC has been used to determine impurities in vinyl chloride monomer used in the manufacture of polyvinyl chloride (PVC) [4]. The analysis was performed using a Perkin Elmer model 8500 GC using a 25 m x 0.53 mm fused silica column coated with 5 pm immobilised methyl silicone phase, the column being run at -10 °C for 4 minutes, programmed at 10 °C/min to 10 °C for 1 minute, and programmed at 30 °C/min to 170 °C for 2 minutes. A FID was employed. The three principal impurities present in the monomer, and, consequently, expected to occur in the PVC, were methyl chloride, monovinyl acetylene, and ethyl chloride. 

Various trace impurities do occur in the vinyl chloride, a number of these such as 1.3 butadiene and monovinyl acetylene can have adverse effects upon the polymerisation kinetics even at very low levels (mg per kg) and thus must be stringently controlled. Any imreactive liquid having a significantly higher boiling point than vinyl chloride, such as EDC, and remaining in the VCM will be foimd in the aqueous effluent, as measures designed to remove VCM will fail to remove them. 

The standard abbreviation in common use today for these rubbers is CR. During World War II it was designated GR-M (Government Rubber-Monovinyl acetylene) and a few contemporary papers may use this designation. 

In the older acetylene route, acetylene is first dimerized to monovinyl acetylene in a concentrated aqueous solution of a complex salt of cuprous chloride. 

The purified monovinyl acetylene is then hydrochlorinated in a concentrated solution of hydrochloric acid and cuprous chloride. The reaction first involves 1,4- addition of hydrochloric acid to give a chlorallene which promptly rearranges to give the desired monomer together with a by-product, l,3-dichloro-2-butene, (Carothers et al., 1932 1933). The dried polychloroprene is then separated from this and other by-products by vacuum distillation in the presence of inhibitors ... 

Details polychloroprene was Invented by DuPont scientists on April 17,1930 after Dr. Elmer K. Bolton of DuPont laboratories attended a lecture by Fr. Julius Arthur NIeuwland, a professor of chemistry at the University of Notre Dame. Fr. Nieuwland s research was focused on acetylene chemistry and during the course of his work he produced divinyl acetylene, a jelly that firms Into an elastic compound similar to rubber when passed over sulfur dichlorlde. After DuPont purchased the patent rights from the university, V fellace Carothers of DuPont took over commercial development of Nieuwland s discovery in collaboration with NIeuwland himself. DuPont focused on monovinyl acetylene and reacted the substance with hydrogen chloride gas, manu cturing chloroprene. ... 

We preferred to find another route which avoided the monovinyl-acetylene required to make 4-chloro-l,2-butadiene ( ), and have devised a route based on 2-butyne-l,4-diol ... 

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