Question

organic chemistry 3 and 4

III. Two unknowns, X and Y, both having the molecular formula C4HsO, give the following results with four chemical tests. Propose structures for X and Y consistent with this information. (6%) Bromine Na meta Chromic acid Lucas reagent Compound X decolorizes Bubbles Orange to greenNo reaction Compound Y No reaction No reaction No reaction No reaction 國立清華大學命題紙 98學年度 生醫工程與環境科學系 系(所) 乙(環境分子科學) 組碩士班入學考試 科目 有機化學與物理化學 科目代碼 2404 共一3.一頁第一3-一頁,請在【答案卷卡】內作答 IV. (a) Optically active 2-bromobutane undergoes racemization on treatment with a solution of KBr. Please (b) In contrast, optically active 2-butanol does not racemize on treatment with a solution of KOH (c) Optically active 2-butanol can racemize in dilute acid. Please propose a mechanism for this show your reaction. (2%) Explain why a reaction like that in part (a) does not occur. (2%) reaction. (4%)

Answer 1

Double bond equivalent (DBE0

X- decolorises bromine. It means it have a double bond.

X- bubbles with Na-metal means acidic hydrogen is present.

X- Converts orange colour to green means an alcoholic group is present.

X- No reaction with Lueas reagent means no tertiary alcoholic group or it has primary alcoholic group

Y- No declorization of poremine means no double bond it means it consists of ring.

Y- No reaction with Na-metal means no acidic -hydrogen present.

Y- Nor reaction with Chromic acid means no alcoholic group.

Y- no reaction with lucas Reagent.