臺灣博碩士論文加值系統

在 N-氧化砒啶的催化下,二氯苯甲醯氯與苯甲酸鈉及其衍生物在
水油兩相反應 系統中進行取代反應,可以生成高產率的不對稱酸干.在
極性較大的有機溶劑中 反應速率較快且酸干產率較高,如二氯甲烷>正
己烷>苯. 在適當條件下,反應遵循下列速率法則: -d[Cl2C6H3
COCl]/dt=kobs[Cl2C6H3COCl] =(kh+kc[PNO]iaq)
[Cl2C6H3COCl] kh為水解反應與無 PNO 存在下二氯苯甲醯氯與相關鈉
鹽反應的綜合視速率常數, kc表PNO與二氯苯甲醯氯在有機相反應的二
級速率常數. 反應速率決定於PNO與二氯苯甲醯氯在有機相的反應,
相對的取代反應速率: 2,4-Cl2C6H3COCl>2,3-Cl2C6H3COCl>3,5-Cl2C6
H3COCl>3,4-Cl2C6H3COCl. 水溶液的pH值會影響反應速率,pH值愈大
則反應速率愈慢,即在酸性下反應較快, 鹼性較慢. 混合有機相
反應物並不會影響個別的反應速率,均依未混合時的反應速率進行, 混
合水相反應物種,得出水相中的陰離子與中間物反應的競爭力大小如下:
(3,4-Cl2C6H3COO-,3,5-Cl2C6H3COO-)>(2,3-Cl2C6H3COO-,2,4-Cl2C6H3
COO-, 4-ClC6H4COO-,3-ClC6H4COO-)>(2-ClC6H4COO-,C6H6COO-).

Abstract The two-phase reaction
of dichlorobenzoyl and the corresponding benzoate with pyridine
N-oxide as the inverse phase transfer catalyst was studied
by using the HPLC method.A more polar organic solvent will lead
to a faster reaction rate and a higher yield of anhydride.
For instance ,dichloromethane as a more proper organic medium
than n-haxane and and benzene in this two-phase reaction.
Under appropriate conditionsa ,the reaction acts according to
the following rate law:-d[Cl2C6H3COCl]/dt=kobs[Cl2C6H3COCl]org
=(kh+kc[PNO]iaq)[Cl2C6H3COCl]org.The process of producing the
intermediate (Cl2C6H3COONP+Cl-)in CH2Cl2 is the rate-determining
step(kc).The order of relative reactivity to PNO in CH2Cl2 is
2,4-Cl2C6H3COCl>2,3-Cl2C6H3COCl>3,5-Cl2C6H3COCl>3,4-Cl2C6H3COCl.
The difference of pH values in aqueous phase will influence the
reaction rate.A faster reaction rate can be acquired if a lower
pH value i given. A mixing of two kinds of dichlorobenzoyl
chloride in CH2Cl2 will not influence the course of respective
reaction. The act as without the existence of each other;
The order of anion' reactivity to the intermediate in aqueous
phase is as follow: (3,4-Cl2C6H3COO- ,3,5-Cl2C6H3COO-)>(2,3-
Cl2C6H3COO-,2,4-Cl2C6H3COO-,4-ClC6H4COO-,3-ClC6H4COO-)>(2-ClC6H4
COO-,C6H5COO-).