Question 1

What is an elimination reaction in organic chemistry?

Accepted Answer

In an elimination reaction, two groups are removed from adjacent carbon atoms and a multiple bond forms between them. In the haloalkane example here, a beta hydrogen and a halide leave, producing an alkene.

Question 2

Why is the C2 atom in 2-bromo-2-methylbutane tetrahedral?

Accepted Answer

C2 forms four sigma bonds: one to Br, one to C1, one to the methyl carbon branch, and one to C3. Four electron domains around carbon give a tetrahedral arrangement rather than a trigonal-planar one.

Question 3

What happens during dehydration of an alcohol?

Accepted Answer

The hydroxyl group is protonated by an acid, changing -OH into -OH2+. Water then leaves, and removal of a beta hydrogen forms the carbon-carbon double bond.

Question 4

Why does concentrated H2SO4 at about 413 K give diethyl ether while at about 443 K it gives ethene?

Accepted Answer

At about 413 K, concentrated H2SO4 promotes intermolecular dehydration of ethanol, producing diethyl ether. At about 443 K, the conditions favor elimination within each ethanol molecule, producing ethene.

Question 5

When can an alkene show E/Z isomerism?

Accepted Answer

Each carbon of the C=C bond must have two different substituents. Neither 2-methyl-2-butene nor 2-methyl-1-butene qualifies, because one alkene carbon has two identical methyl groups and the other has two identical hydrogen atoms.

Elimination in Hydrocarbons: Where the Double Bond Forms

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