Lucas' reagent
A solution of zinc chloride in concentrated hydrochloric acid, used to classify alcohols of low molecular weight. The reaction is a substitution in which the chlorine replaces the hydroxy group. Even though this reaction is normally very unfavorable, the zinc ion complexes with the hydroxy group, making it a better leaving group. The rate at which the reaction procedes is indicative of the type of alcohol: - no visible reaction: primary alcohol
- solution turns cloudy in 3-5 minutes: secondary alcohol
- solution turns cloudy immediately, and/or phases separate: tertiary, allyl, or benzyl alcohol
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