3-Chloro-2-methylpropene

Chloro-2-methylpropene (methallyl chloride) is available from Fluka A G and Eastman Organic Chemicals. The chloride, b.p. 72° (760 mm.), was distilled before use. 

Chemical Designations - Synonyms gamma-Chloroisobutylene 3-Chloro-2-methylpropene beta-Methallyl chloride beta-Methylallyl chloride Chemical Formula CH2=C(CH3)CH2C1. 

Chloro-2-methylpropene Sodium chloride Thionyl chloride Sodium hydroxide... 

A mixture of 5-chloromethyl salicylate, 3-chloro-2-methylpropene, potassium carbonate, and acetone was heated at reflux overnight. After cooling, the mixture was extracted with diethyl ether and ethyl acetate. The organic extracts were combined, washed twice with a 10% sodium chloride solution and water, dried over sodium sulfate, and concentrated in vacuum. The resulting liquid was vacuumed distilled. The fraction collected and the desired 5-chloro-2-(2-methyl-2-propenyloxy)benzoic acid, methyl ester was obtained. 

Sodium amide (2.79 mol) and 110 ml light mineral oil were heated to 45 °C whereupon hexamethyldisilazane (0.03 mol) was added. Over 50 minutes, 3-chloro-2-methylpropene (2.23 mol) was slowly added and the evolving gas scrubbed with water then condensed in a dry ice cooled trap. The total product weight consisted of 39.5 g of which 39.3 g comprised 1-methyl-cyclopropene. 

An allyl halide, 3-chloro-2-methylpropene, was converted to 3-methyl-3-butenoic acid in 82% yield after 1 hr of reaction at room temperature. Wagner [65] converted 3-chloro-2-methylpropene to the Grignard in 81% yield after 10 hr at 14-16 C, and obtained 3-methyl-3-butenoic acid from the Grignard in 40% yield after CO2 quench. 

Chloro-2-methylpropyl(propyl)borane (18.8 g, 0.1 mol), prepared from tetrapropyldiborane (9.8 g, 0.05 mol) and 3-chloro-2-methylpropene, was added dropwise with stirring at 120-130°C to a solution of sodium tetrapropylborate (20.6 g, 0.1 mol) in abs. xylene (80 mL). Methylcyclopropane distilled off immediately and was condensed in a cooling trap at — 78 "C. NaCl precipitated. The reaction ceased after 45 min. Yield (cooling trap) 5.4 g (96.5%) purity 98% (2% propene). 26.5 g (94.6%) of tripropylborane was recovered by distillation of the reaction mixture. 

Methylenecyclopropane from 3-Chloro-2-methylpropene and Sodium Amide33 ... 

CHLORO-2-METHYLPROPENE (563-47-3) Forms explosive mixture with air (flash point 11°F/-12°C cc). Slowly hydrolyzes in water, forming methallyl alcohol and hydrochloric acid. Strong oxidizers may cause fire and explosions. Contact with acids or acid fumes produces highly toxic chloride fumes. Aqueous solution is incompatible with sulfuric acid, alkalis, ammonia, aliphatic amines, alkanolamines, alkylene oxides, amides, boranes, epichlorohydrin, nitromethane, organic anhydrides, isocyanates, vinyl acetate. In the presence of moisture, attacks metals can cause pitting and stress corrosion in austenitic stainless steels. 

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