Cyclopentene chlorination

Poly(pentenamer), Poly(cyclopentene) Chlorinated hydrocarbons. Alcohols, aliphatic ketones, ethers 43... 

Finally, the addition of IC1 gives a mixture of the tricyclic monoiodides 80a and 80b and of the product from addition of iodine and chlorine at the cyclopentene double bond (equation 82). 

Cyclopentane bromohydroperoxides, stereoisomerism, 313, 314 Cyclopentene, primary ozonide, 720 Cycloperoxy chlorination, 1,2-dioxolane synthesis, 238, 240... 

The cold filtrates (solutions of monochlorourea) are transferred to a 3-1. two-necked flask immersed in an ice-salt bath. The flask is equipped with a slip- or mercury-sealed mechanical stirrer and an efficient reflux condenser. To the flask are added 500 g. of ice, 100 ml. of glacial acetic acid, and 136 g. (2.0 moles) of cyclopentene (or 1.43 times the weight increase in grams during introduction of the chlorine) (Note 4). Mechanical stirring is begun, and is continued while the flask is kept packed in ice until the cyclopentene (the top layer) disappears and a heavy oil settles to the bottom (Note 5). 

Thus, there are three different monochloro-substituted derivatives of cyclopentene. The carbons that bear the double bond are numbered C-l and C-2 in each isomer, and the other positions are numbered in sequence in the direction that gives the chlorine-bearing carbon its lower locant. 

Halohydrins are easily generated by treating alkenes with aqueous solutions of halogens. Bromine water and chlorine water add across double bonds with Markovnikov orientation (Section 8-11). The following reaction shows cyclopentene reacting with chlorine water to give the chlorohydrin. Treatment of the chlorohydrin with aqueous sodium hydroxide gives the epoxide. 

How does the proposed mechanism invoking a bridged halonium ion intermediate explain the observed trans products of halogenation For example, chlorination of cyclopentene affords both enantiomers of rram-l,2-dichlorocyclopentane, with no cis products. 

In l-chloro-2-hydroperfluorocyclobutene and cyclopentene, direct reaction of hydride substitutes hydrogen for chlorine (1), while allylic reduction leads to replacement of fluorine (2) (equation 6, Table 3). ... 

The cleavage of the benzene ring by meaus of chlorine in alkaline solution has bear further investigated by Hantzsch This work has been summarized in the form of tabular statements which indicate the transformation of the various substances into chlorinated keto-derivatives and ultimately into cyclopentenes and their decomposition products.51... 

Christman et al. (1978) also chlorinated resorcinol, showing that during chloroform formation it underwent ring contraction to produce the unusual cyclopentene-dione 25. Larson and Rockwell (1979) confirmed Rook s and Christman s observations that resorcinol derivatives were active haloform precursors, and also found that even if the 2-carbon of resorcinol was blocked by a carboxyl group (cf. 26), yields of... 

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