Cyclopentyl chloride

Cyclopentanepropanoic acid, c405 Cyclopentene oxide, e42 Cyclopentyl bromide, b313 Cyclopentyl chloride, c93 Cyclopropyl bromide, b314 Cyclopropyl cyanide, c407... 

Propane and cyclopentane give isopropyl chloride and cyclopentyl chloride, respectively, whereas isobutane is transformed to ferf-butyl chloride under the same reaction conditions (yields are 69%, 74%, and 76%, respectively). Neopentane undergoes isomerization to yield 2-chloro-2-butane (88%). When saturated, hydrocarbons were allowed to react with methylene bromide and SbF5 bromoalkanes were obtained in comparable yields (64-75%). Formation of the halogenated product can be best explained by the mechanistic pathway (I) depicted in Scheme 5.55. Since SbF5 always contains some HF, mechanism (II) may also contribute to product formation (Scheme 5.55). 

Cyclopentyl bromide, b263 Cyclopentyl chloride, c79 Cyclopropyl bromide, b264 Cyclopropyl cyanide, c365... 

Cyclopentane Cyclopentyl chloride Cyclopentene Cyclopentyl iodide... 

Cyclopentyl chloride (79) reacts under irradiation with Ph2P ions to give product 80. This reaction was almost completely inhibited by p-DNB (equation 65)151. 

The main product, cyclopentyldichlorosilane, can be explained by the reaction of one equivalent of silicon with one equivalent of cyclopentyl chloride and hydrogen chloride. The hydrogen chloride used for the reaction should have been formed by the decomposition of cyclopentyl chloride. 

In the direct reation of cyclopentyl chloride, hydrogen chloride addition to the cyclopentyl chloride reactant did not have much effect but gave about the same result as without hydrogen chloride addition. This may be explained by the rapid decomposition of cyclopentyl chloride to provide enough hydrogen chloride to produce cyclopentyldi-chlorosilane. 

Cyclopropyl chloride has a dipole moment of 1.76 D compared with 2.04 D in cyclopentyl chloride L... 

Figure 2 Four representative Grignard reagents plotted according to Eq. (5) cyclohexyl bromide vs. cyclopentyl bromide ( ) cyclopentyl chloride vs. cyclopentyl bromide (A) n-pentyl chloride vs. cyclohexyl chloride ( ) neopentyl bromide vs. cyclopentyl bromide (O)- (From Ref. 81b.)...

Table 10 Relative Rates of Reaction of Cyclopentyl Bromide and Cyclopentyl Chloride with Magnesium in Several Solvents...

Further work [8IQ, which demonstrated that the rates of reaction of cyclopentyl bromide with magnesium fit the kinetic features of a transport-limited heterogeneous reaction, was based on two sets of experiments. First, the relative rates of reaction of cyclopentyl bromide and cyclopentyl chloride with magnesium in solvents of different viscosities [8If] were examined by applying the constant-surface kinetics technique. The results are summarized in Table 10. These demonstrate that the relative rates of reaction of cyclopentyl bromide with magnesium in a series of solvents were proportional to the inverse of the solvent shear viscosity whereas the reaction of cyclopentyi chloride... 

To test these alternative hypotheses, a tremendous amount of work has been done, by Brown and by others. For example, camphene hydrochloride is known to undergo ethanolysis 6000 times as fast as rer/-butyl chloride, and this had been attributed to anchimeric assistance with formation of a bridged ion. Brown pointed out that the wrong standard for comparison had been chosen. He showed that a number of substituted (3°) cyclopentyl chlorides (examine the structure of camphene hydrochloride closely) also react much faster than rerr-butyl chloride. He attributed these fast reactions—including that of camphene hydrochloride—to relief of steric strain. On ionization, chloride ion is lost and the methyl group on the ap hybridized carbon moves into the plane of the ring four non-bonded interactions thus disappear, two for chlorine and two for methyl. For certain systems at least, it became clear that one need not invoke a nonclassical ion to account for the facts. 

---