1-Bromo-l-methylcyclohexane

Heterolysis rates of r-butyl bromide, 1-bromo-l-methylcyclohexane, and 2-bromo-2-methyladamantane increase in the order of solvents MeCN < y-butyrolactone < sulfolane, but heterolysis rates of 2-bromo-2-phenyladamantane decrease in the same order of solvents. The observed effects are considered to be caused by superposition of dipolar and electrophilic solvations. 

I) 1-Bromo-l-methylcyclohexane (II) 2-Chloro-2-methylbutane (III) 2,2,3-TrImethyl-3-bromopentane. 

A-8. Write a mechanism describing the solvolysis (SN1) of 1-bromo-l-methylcyclohexane in ethanol. 

When 1-bromo-l-methylcyclohexane is heated in ethanol for an extended period of time, three products result one ether and two alkenes. Predict the products of this reaction, and propose a mechanism for their formation. Predict which of the two alkenes is the major elimination product. 

Similarly, the reaction of 1-bromo-l-methylcyclohexane with sodium ethoxide gives a mixture of a disubstituted alkene and a trisubstituted alkene. The trisubstituted alkene is the major product. 

Show how you would accomplish the following synthetic conversions, (a) Convert 1-methylcyclohexene to 1-bromo-l-methylcyclohexane. 

Regioselectivity (orientational control) is the formation of one constitutional isomer as the major product in which two or more constitutional isomers could be obtained. For example, addition of HBr (hydrogen bromide) to 1-methylcyclohexene (1.29) gives 1-bromo-l-methylcyclohexane (1.30) as the main product and l-bromo-2-methylcyclohexane (1.31) is formed as the minor product. 

There are two alkenes that react with HBr to give 1-bromo-l-methylcyclohexane. 

Bromo-l-methylcyclohexane is not correct. It gives a mixture of 1-methylcyclohexene and methylenecyclohexane on elimination. 

Markovnikov addition, - of simple alkenes. In other words, addition of HCl, HBr, or HI to substituted alkenes will lead to an alkyl halide where the nucleophile is attached to the more substituted carbon of the Jt-bond. The basis of this regioselectivity is, of course, formation of the more stable carbocation, 295, which is attacked by bromide ion to give 1-bromo-l-methylcyclohexane (296). This is the normal course of all reactions with acid and an alkene if the intermediate is a cation. In section 2.7.B.ii, the reaction of 100 with HCl is an example of this type of reaction. 

Predict the product of the reaction of 1-bromo-l-methylcyclohexane with... 

Regioselective reaction An addition or substitution reaction in which one of two or more possible products is formed in preference to all constitutional isomers that might be formed. Addition of HBr to 1-methylcyclohexene gives 1-bromo-l-methylcyclohexane to the virtual exclusion of l-bromo-2-methylcyclohexane. 

Scheme 6.30. A representation of the addition of hydrogen bromide (HBr) to 1-methylcyclohexene in acetic acid (CH3CO2H), that is, under acidic conditions, showing that the solvent intrudes into the electrophihc addition reaction. The intrusion of solvent will complicate the kinetic arguments. Initially, the formation of 1-bromo-l-methylcyclohexane is first order in alkene and first order in hydrogen bromide (HBr) only at low (HBr).The kinetics become much more complicated as the reaction progresses.

Example 2. Starting with 1-bromo-l-methylcyclohexane, how could you prepare trans-... 

Conclusions. The bromine atom must now be located at the same position as the CH3 substituent, as in the achiral 1-bromo-l-methylcyclohexane ... 

The reaction of f-l-methylcyclohexanol with HBr yields 1-bromo-l-methylcyclohexane. Write a mechanism to explain the origin of this product. 

Which compound in each of the following pairs reacts at the faster rate with sodium iodide in an Sjj2 process to yield an alkyl iodide (a)l-chlorohexane or 2-chlorohexane (b) bromocyclohexane or 1-bromo-l-methylcyclohexane... 

The starting material (1-bromo-l-methylcyclohexane) is a tertiary alkyl halide, and will undergo an E2 reaction when treated with a strong base such as methoxide, to give the more substituted alkene... 

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