| Summary: | 碩士 === 國立成功大學 === 化學系 === 84 === 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-).
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