Fert-Butyl chloride

FIGURE 4.6 The mechanism of formation of fert-butyl chloride from tert-butyl alcohol and hydrogen chloride. 

FIGURE 4.11 Combination of terf-butyl cation and chloride anion to give fert-butyl chloride. In-phase overlap between a vacant p orbital of (CHbIbC" and a filled p orbital of Cr gives a C—Cl CT bond. 

From acid chlorides and alcohols RCOCI + R OH — RC02R + HCi Versatile reaction works well with prim., sec., and tert. alcohols a base may be necessary to remove HCI, because tert-aliphatic alcohols may give alkenes and fert-butyl chlorides. 

First convert fert-butyl chloride into an isobutyl halide. 

Analogous reactions are used to manufacture sec-butyllithium and ferf-butyl-lithium using 2-chlorobutane (scc-butyl chloride) and 2 chloro-2-methylpropane (fert-butyl chloride), respectively, as shown in eq 4.13 and 4.14 ... 

We have accounted for the observed change in carbon skeleton, but we have not answered two questions that have plagued the organic chemist for a generation. Why is only the exo chloride, isobornyl chloride, obtained, and none of its endo isomer, bornyl chloride Why does camphene hydrochloride undergo solvolysis thousands of times as fast as, say, fert-butyl chloride To sec the kind of answers that have been given, let us turn to a simpler but basically similar system. 

When benzene is treated with fert-butyl chloride and aluminium trichloride, a crystalline product A is formed that contains only C and H. Mass spectrometry tells us the molecular mass is 190. The H NMR spectrum looks like this ... 

Chloro-2-methylpropane Water (fert-butyl chloride) (78-88%)... 

PROBLEM 6.11 Is the electrophilic addition of hydrogen chloride to 2-methyl-propene the reverse of the El or the E2 elimination reaction of fert-butyl chloride J... 

Solvent Effects on the Rate of Substitution by the Sj l Mechanism. Table 8.6 lists the relative rate of solvolysis of tert-butyl chloride in several media in order of increasing dielectric constant (e). Dielectric constant is a measure of the ability of a material, in this case the solvent, to moderate the force of attraction between oppositely charged particles compared with that of a standard. The standard dielectric is a vacuum, which is assigned a value of exactly 1. The higher the dielectric constant , the better the medium is able to support separated positively and negatively charged species. Solvents with high dielectric constants are classified as polar solvents. As Table 8.6 illustrates, the rate of solvolysis of fert-butyl chloride (which is equal to its rate of ionization) increases dramatically as the dielectric constant of the solvent increases. 

The first-order rate constant for ethanolysis of the allylic chloride 3-chloro-3-methyl-l-butene is over 100 times greater than that of fert-butyl chloride at the same temperature. 

Step 1 Once generated by the reation of fert-butyl chloride and aluminum chloride, rerf-butyl cation attacks the TT electrons of benzene, and a carbon-carbon bond is formed. 

The reaction of ferT-butyl chloride with cyanide ion proceeds by elimination rather than substitution. 

Compound A is therefore 2-methylpropane, the two alkyl chlorides are fert-butyl chloride and isobutyl chloride, and alkene B is 2-methylpropene. 

The problem states that the reaction is first order in (CHjljCCl (fert-butyl chloride) and first order in NaSCHjCHj (sodium ethanethiolate). It therefore exhibits the kinetic behavior (overall second order) of a reaction that proceeds by the E2 mechanism. The base that abstracts the proton from carbon is the anion CH3CH2S . 

The compounds of molecular formula C4H9CI are the isomeric chlorides butyl, isobutyl, 5cc-butyl, and fert-butyl chloride. 

Formation of fert-Butyl Chloride from terf-Butyl Alcohol and Hydrogen Chloride 149... 

A fundamentally similar situation is obtained with the initiation of styrene by alkylaluminum halides or trialkylaluminum compounds. In the case of this monomer the demarcation between poor and good coinitiators is perhaps even more evident than with isobutylene. Fig. 2 shows the essential data obtained in a series of experiments in which various alkyl chlorides were added to styrene/Al(C2H5)2Cl charges in methyl chloride 24). Alkyl halides with high R—Cl heterolytic bond dissociation energies are very poor coinitiators compared with those with lower dissociation energies. Thus 3-chloro-l-butene, crotyl chloride, fert-butyl chloride, 1-chloroethylbenzene and diphenyl chloromethane are efficient because the carbocations which arise from these chlorides... 

Dissolving fert-butyl alcohol in concentrated (coned) aqueous hydrochloric acid soon results in the formation of fert-butyl chloride. The reaction is a substitution reaction ... 

Because iodide ion is a better leaving group than chloride ion, tert-hutyl iodide reacts over 100 times faster than fert-butyl chloride. Yet the ratio of products is the same. 

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