3.4- Dichloro-l-butene

Substantial amounts (24% and 12%, with and without catalyst, respectively) of l,3-dichloro-2-butene arising from bromine-chlorine exchange were formed. h ... 

Dichlorobutane, 36, 89 l,3-Dichloro-2-butene, 35, 20 38, 71 -Di(chloro-ferf-butyl)benzene, 32, 91 4,4 -Dichlorodibutyl ether, 30,27... 

When the reaction is performed using l,3-dichloro-2-butene as the alkyl halide, the indanone derivative 11 is formed in excellent yield (99%) and with high (92%) ee (Scheme 3.3, Eq. 1) [6]. Products of type 11 are interesting intermediates for preparation of optically active tricyclic enones, which are obtained after hydrolysis and Robinson annelation [6]. 

One hundred and twenty-five grams of l,3-dichloro-2-butene (1.0 mole) (Note 4) is added at a rate of about 3 drops per second. Addition should be complete in 0.75-1 hour (Note 5). During the addition the temperature of the oil bath is maintained at 165-170° (Note 6), and the reaction mixture is stirred vigorously. Heating is continued for 1 hour after the addition of dichlorobutene is complete. 

The use of organic halogen compounds as the starting products for the synthesis of other organic chemicals is too immense a field to do more than indicate some of the commercial applications. In his book I4S) on the chemistry of petroleum derivatives, Ellis includes a chapter on the production of alcohols and esters from alkyl halides, and also one on miscellaneous reactions of halo-paraffins and cycloparaffins. The manufacture of amyl alcohols and related products from the chlorides has been well covered 14 ) 1 )-A two-step process for the synthesis of cyclopropane by chlorinating propane from natural gas and dechlorinating with zinc dust was devised in 1936 152). A critical review of syntheses from l,3-dichloro-2-butene was published in Russia in 1950 (1-54). The products obtainable from the allylic chlorides are covered in a number of articles 14If 14 157). 

The synthesis of dialkyl 3-oxoalkylphosphonates proceeding by treatment of dialkyl 1-cop-per(I)alkylphosphonates with 2,3-dihalopropenes has been extended to dialkyl 4-oxoalkylphospho-nates. Thus, l,3-dichloro-2-butene is readily coupled with dialkyl l-copper(I)alkylphosphonates at -35°C, and then the hydrolysis of the resulting vinyl halide with H2SO4 in biphasic medium at low temperature releases the 8-keto functionality (Scheme 7.61). " In this way 1-substituted or unsubstituted diethyl 4-oxoalkylphosphonates are readily prepared in high yields (79-85%). " ... 

In a 3-1. three-necked round-bottomed flask fitted with a reflux condenser and a mercury-sealed stirrer, 250 g. (2 moles) of l,3-dichloro-2-butene (Note 1) and 1.25 1. of 10% sodium carbonate are heated at reflux temperature for 3 hours. The 3-chloro-2-buten-l-ol is extracted with three 300-ml. portions of ether, which are then dried over anhydrous magnesium sulfate. The ether is removed by distillation through a 20-cm. Fenske column, and the residue is distilled from a 250-ml. Claisen flask, yielding 134 g. (63%) of 3-chloro-2-buten-l-ol, b.p. 58-60°/8 mm., 1.4670. 

Annelation l,3-Dichloro-2-butene. 2,3-Dimethyl-2-butylborane. 3,5-Dimethyl-4-chloro-methylisoxazole. Methyl vinyl ketone. (rons-3-Pentene-2-one. Pyrrolidine. 

Moisture must be completely excluded because sodamide readily becomes coated with sodium hydroxide it is thus advisable to prepare the reagent shortly before use by reaction of sodium with anhydrous liquid ammonia192 in the presence of iron(m) chloride or nitrate.190 2-Butyn-l-ol (7) is then obtained in 80% from 3-chloro-2-buten-l-ol (6) by way of its sodium salt, the original starting material being l,3-dichloro-2-butene 193... 

The Wichterle reaction sequence is the annulation of a ketone to a cyclic enone using l,3-dichloro-2-butene (1), the Wichterle reagent, via a three-step process consisting of an alkylation, hydrolysis, and intramolecular cyclization. 

Due to the vast synthetic utility of annulation reactions, there are numerous analogous sequences that can be performed to reach the same class of products as the Wichterle reaction. The most notable of which is the Robinson annulation, which uses methyl vinyl ketone in place of 1,3-dichloro-2-butene. Later research has elaborated on the Wichterle reagent by constructing an extensive library of methyl vinyl ketone surrogates 9-14 that can be employed in a manner analogous to l,3-dichloro-2-butene. Despite the development of annulation reagents like 9-14, 1,3-dichloro-2-butene retains ample synthetic utility due to both its commercial availability and its ability to be trivially prepared from ethyl acetoacetate or methyl acetoacetate. ... 

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 ... 

Allyl chloride, " propenyl chloride isomers, trichloroethylene,l,3-dichloro-2-butene, 3-chloro-2-chloromethyl-1-propene, and chloroprene are all claimed to undergo alternating copolymerization with MA. Isopropenyl chloride is essentially nonpolymeriz-able by both free-radical and ionic initiators. However, mixtures of isopropenyl chloride and MA in benzene with AIBN, at 60°C, copolymerize quite readily to give colorless materials, with relatively high viscosities. The composition of the copolymers were found to be independent of monomer feed ratio and to consist essentially of a 1 1 composition of the monomer pair. In contrast, cis- and -propenyl chloride exhibit low copolymerization rates with MA and the resultant copolymers exhibit much lower specific viscosities than the isopropenyl chloride-co-MA polymers. 

Poly(diacetone acrylamide-alt-MA), 382 Poly(l,2-dialin-alt-MA), 379 Poly(diallyl ether-co-MA), 314, 315, 348 Poly(diallylidene pentaerythritol-co-MA), 332 Poly(dibenzalacetone-alt-MA), 334 Poly(di-/i-butyltin fumarate), 492 Poly(2,3-dichlorobutadiene-alt-MA), 346, 381 Poly(l,3-dichloro-2-butene-alt-MA), 380 Poly(l, r-dicyclohex-2,2-enyl ether-co-MA),... 

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