Chapter 13, Problem 34P

Interpretation Introduction

Interpretation:

The reason behind the formation of a conjugate diene by dehydrohalogenation of 1,2-dibromocyclcohexane, when, generally, dehydrohalogenation of dihalides leads to alkynes instead of conjugated dienes, is to be explained.

Concept introduction:

舧 Electrophiles are electron-deficient species, which has positive or partially positive charge. Lewis acids are electrophiles, which accept electron pair.

舧 Nucleophiles are electron-rich species, which has negative or partially negative charge. Lewis bases are nucleophiles, which donate electron pair.

舧 Free radical is an atom, molecule, or ion that has an unpaired electron, which makes it highly chemically reactive.

舧 Substitution reaction: A reaction in which one of the hydrogen atoms of a hydrocarbon or a functional group is substituted by any other functional group is called substitution reaction.

舧 Elimination reaction: A reaction in which two substituent groups are detached and a double bond is formed is called elimination reaction.

舧 Addition reaction: It is the reaction in which unsaturated bonds are converted to saturated molecules by the addition of molecules.

舧 The reaction in which the halide group and hydrogen group are removed to form alkene is called dehydrohalogenation.

舧 The reaction in which hydrogen is added to the compound in the presence of catalyst is known as hydrogenation.

舧 The number of moles of hydrogen absorbed will be equal to the number of double bonds.

舧 Alkynes are synthesized by dehydrohalogenation of dihalides using a strong base and a strong nucleophile via E2 elimination reaction.

舧 The linear nature of the $\text{C}-\text{C}\equiv \text{C}-\text{C}$ alkyne group in a six-membered cyclic chain puts high strain on a cyclic six-membered hydrocarbon.