Alkyd halides

AJkynfMi are hydrocarbons that contain one or more carbon-carbon triple bonds. Alkyne carbon atoms are sp-hybridizcd, and the triple bond consists of one sp 4fp o bond and l fo p p bonds. There are relatively few genera) methods of alkyne synthesis. The two best are the alkylation of an acetylide anion with a piimao alkyd halide and the twofold elimination of HX fratn a vicinal dihalide. 

Esters are usually prepared from carboxylic acids by the methods already discussed. Thus, carboxylic acids are converted directly into esters by S <2 reaction of a carboxylate ion with a primary alkyd halide or by Fischer esterification of a carboxylic acid with an alcohol in the presence of a mineral acid catalyst. In addition, acid chlorides are converted into esters by treatment with an alcohol in the presence of base (Section 21.4). 

The activating group stabilises the enolate anion (9) by conjugation so that the keto ester (8) can be converted entirely into (9) with EtO. No reaction of (9) with (8) occurs, partly because (9) is so much more stable than (7), and partly because no (8) is left. The alkyd halide is added in a separate step so that no base remains to form an anion of the product. 

Alizarin, 981 Alkyd resins, 1018 Alkyl borates, 302 Alkyl bromides, 270 Alkyl chlorides, 270 Alkyl fluorides, 272 Alkyl halides, 270... 

Mono- and di-alkylacetylenes are prepared from sodium alkydes and primary alkyl halides which lack branching on the second carbon atom. The branched primary halides as well as secondary and tertiary halides undergo dehydrohalogenation to olefins by the basic alkyde. The alkydes are best prepared from the acetylenes and sodium amide in liquid ammonia.The yields of 1-alkynes are frequently 70-90% when alkyl bromides are employed as alkylating agents. Dialkylacetylenes... 

Acetylenic Grignard reagents are less active than sodium alkydes but are readily alkylated by benzyl halides as well as by alkyl sulfates and sulfonates.. . The Grignard reagents are conveniently prepared from the acetylenes and ethylmagnesium bromide in ether solution. 

The first truly synthetic resin was developed by Baekeland in 1911 (phenol-formaldehyde). This was soon followed by a petroleum-derived product called coumarone-indene, which did indeed have the properties of a resin. The first synthetic elastomer was polychloroprene (1931) originated by Nieuwland and later called neoprene. Since then many new types of synthetic polymers have been synthesized, perhaps the most sophisticated of which are nylon and its congeners (polyamides, by Carothers), and the inorganic silicone group (Kipping). Other important types are alkyds, acrylics, aminoplasts, polyvinyl halides, polyester, epoxies, and polyolefins. 

Alkyd resins Aromatic hydrocarbons, hydrocarbon halides, hydrocarbons, lower alcohols, ketones, esters Hydrocarbons... 

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