In each of the following indicate which reaction will occur faster. Explain your reasoning. (a) CH3CH2CH2CH2Br or CH3CH2CH2CH2I
with sodium cyanide in dimethyl sulfoxide (b) 1-Chloro-2-methylbutane or 1-chloropentane with sodium iodide in acetone (c) Hexyl chloride or cyclohexyl chloride with sodium azide in aqueous ethanol (d) Solvolysis of 1-bromo-2,2-dimethylpropane or tert-butyl bromide in ethanol (e) Solvolysis of isobutyl bromide or sec-butyl bromide in aqueous formic acid (f) Reaction of 1-chlorobutane with sodium acetate in acetic acid or with sodium methoxide in methanol (g) Reaction of 1-chlorobutane with sodium azide or sodium p-toluenesulfonate in aqueous ethanol
A. Butyliodide will react faster than butylbromide, this is because iodide is a better leaving group in substitution reaction than bromide. B. 1-chloropentane is more reactive than 1-chloro2methylbutane, this is because Alkyl groups at the carbon atom decrease the reaction rate of SN2 reaction. C. Chloro- hexanechloride is more reactive than hexyl chloride because determining the rate of reaction in SN1 reaction of formation of carbocation is more stable than the primary one. SN1 reaction is a secondary carbocation reaction. D. Terri-butylbromide is more reactive than 1-bromo 2,2 dimethylpropane, this is because Tertiary carbocation is stable compared to the primary, this is because the rate of determining step involved in SN1 reaction. E. Sec-butyl bromide is more reactive than isobutylbromide, this is because Sec-butyl bromide belong to the secondary all halide why the other belongs to primary class. F. The reaction is faster in sodium methoxide in methanol than sodium acetate in acetic acid, this is because 1-chlorobutane is a primary alklyl- chloride than and the strength of nuclephile determines the rate of reaction. G. when sodium azide mixed with ethanol is used, the reaction will be faster, because strong acid form weak conjuage base and also azide is a better nuclephile.
