- 作者： 張德洲
- 作者服務機構： 私立中原理工學院
- 中文摘要：
對合成薄荷腦之最廉價工業原料thymol行還原與異性化反應。
蘭尼鎳，由鎳鋁鐵三元合金展開之還原鎳，安定化鎳及Copper chromiumoxide
等為催化還原之催化劑“檢討還原溫度、時問、氫氣壓力，催化劑添加量等最適當的還原
條件並比較其優劣“結果以Copper chromium oxide還原時需較高溫度，且不易產
生副生物，例如在220~2300C時可得理論量的還原生成物一薄荷腦異性體混合物一其
中的消旋薄荷腦含量為43％。以安定化鎳還原時，130o-150oC就可得到理論量的還
原生成物，其中的消旋薄荷腦含量為38%。
將此還原生成物一薄荷腦異性體混合物一在氫氣壓力下行催化異性化反應，當反應達
到平衡時消旋薄荷腦之最高含量為46%“如反應系中含有羰基化合物例如薄荷醇，或第
一級烴基化台物例如甲醇、乙醇等時阻礙異性化反應而以脫水反應為主“所以蘭尼鎳等展
開後需用醇類處理之催化劑不適直於異性化反應“當利用金屬鈉行異性化反應，達到平衡
時消旋薄荷腦之含量，在無溶劑情況下約為70%，如薄荷酮為溶劑時約為75州，如高
沸點的decaline為溶劑時約為80彫。
薄荷腦(L-menthol)在醫藥品，糖?工業方面需要量甚大，僅僅依靠天然產品不足供應
，因而有合成薄荷腦工業之興起“薄荷腦因具有3個不對稱碳原子故能有8種同分異構體，天
然薄荷腦之構造為如圖 - 英文摘要： Thymol was catalytic hydrogenated and isomerized in the presence of catalystsuch as Raney Nickel, reduced nickel which is developed from Nl-Al-Fe alloy,stabilized nickel and copper chromium oxide. In a study of the effects of reaction temperature, reaction time, hydrogenpressure ane nature of the catalyst to the yield and composition of hydrogenationproducts-mixture of menthol isomers, it was found that the optimum conditionfor hydrogenation of thymol with copper chromium oxide catalyst at 220-230oC,yields a theoritical volume of a mixture of menthol isomers, containing 43% dl-menthol and with stabilized nickel catalyst at 130-150oC,yields a theoritical volumeof a mixture of menthol isomers, containing 38% dl-menthol. The catalytic isomerization of the hydrogenation products-- a mixture ofmenthol isomers一by means of Raney Ni, under the hydrogen pressure (30 atm)was investigated. It was shown that the equilibrium menthol mixtures was contained46%dl-menthol. In the case of catalytic isomerization, if the carbonyl compound such asmenthone or primary hydroxy compound such as methanol was present, theisomerization was considerable inhibited and the main reaction was dehydration.The isomerization of a mixture of menthol isomers by means of sodium mentholatewas also studied. It was shown that the equilibrium menthol mixture contained70%dl-menthol with absent of solvent，75%dl-menthol with the menthone assolvent and 80% dl-menthol with high b. p. solvent such as decaline.
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- 英文關鍵字： --
