8-1 Preparing Alkenes:A Preview of Elimination Reactions Preparation of alkenes:elimination reactions Precursors to alkenes Biological systems-usually alcohols Laboratory-either alcohols or alkyl halides Alkenes and alcohols are chemically related through addition and elimination reactions Alkenes add H2O to form alcohols Alkenes add HX to form halides Alcohols eliminate water to form alkenes Alcohols eliminate HX to form alkenes Addition X-Y EliminationPreparation of alkenes: elimination reactions Precursors to alkenes ▪ Biological systems – usually alcohols ▪ Laboratory – either alcohols or alkyl halides Alkenes and alcohols are chemically related through addition and elimination reactions ▪ Alkenes add H2O to form alcohols ▪ Alkenes add HX to form halides ▪ Alcohols eliminate water to form alkenes ▪ Alcohols eliminate HX to form alkenes 8-1 Preparing Alkenes: A Preview of Elimination Reactions