C氮環化合物在多相反應系統之反應動力學

Kinetics of a Sequential Phosphazene Reaction in a Multi-phase System

蒙上欣(Shang-Shin Meng)

指導教授 ： 吳和生

元智大學/工程學院/化學工程與材料科學學系/碩士(1996年)

摘要

有機磷氮環化合物能應用於液壓流體、潤滑劑或黏著劑。相間轉移觸
媒技術對於合成非均相的化學反應是一種非常有用的工具。本研究即利用
相間轉移觸媒技術(phase-transfer catalyst)，使反應物六氯環三偶磷
氮(hexachlorocyclotriphosphazene；((NPCl2)3)和酚(phenol；C6H5OH)
在多相系統(單相、水油兩相、水油樹脂三相)中進行取代反應，合成多苯
氧基環狀偶磷氮(partial(phenoxy)chlorocyclotriphosphazene)。並在
反應過程中觀察反應物的消耗與各個產物的生成情形做一研究。研究相間
轉移觸媒反應有三個論題需被暸解，包括(i)油水兩相反應速率，(ii)觸
媒於油水兩相之質傳，(iii)觸媒於兩相平衡時之分配比。因此動力學行
為、質傳效應、水油兩相濃度現象皆是被討論的相關問題。由本研究獲得
下列肯定的結論：(1)本反應系統經加入微量相間轉移觸媒後，反應速率
快速增加。而所得之產物以加壓管柱層析法及冷卻結晶法純化。根據31P-
NMR光譜，本反應途徑循著反式-非孿式(trans-nongeminal)途徑。且由實
驗數據、電子效應與立體障礙效應可知本系統為SN2形式機構。(2)在本反
應中，虛擬一次反應速率常數會隨著最初加入之六氯環三偶磷氮的濃度而
改變。因此推知本反應受化學動力與質傳的影響。觸媒於兩相中的質傳符
合虛擬穩定狀態液液相間轉移觸媒反應模式，且此連續取代反應的本質速
率常數與觸媒從油相到水相的總質傳係數可由一合併的數學模式求出。此
外，連續取代反應的活化能、活化熵、活化焓也可被求得。(3)由實驗知
氫氧化鈉的功能與相間轉移觸媒反應其彼此間的關係如下：(i)鹽析(
salting out)中間產物即觸媒苯氧化四丁基銨至有機相；(ii)減少觸媒與
水之溶合(solvation)進而改善有機相內活性觸媒之反應能力和改變觸媒
在兩相間之質傳能力。(4)由於兩相相間轉移觸媒不易回收，故把相間轉
移觸媒固定於由苯乙烯(styrene)，氯鉀基苯乙烯(chloromethylstyrene)
和二乙烯基苯(divinylbenzene)所合成的高分子擔體上，以利於回收，而
成為三相觸媒。在本論文中利用三相觸媒合成偶磷氮化合物，發現油相置
換反應受到擔體顆粒擴散和本質化學反應控制，水相離子交換反應受到薄
膜擴散控制。(5)在本研究中分析環三偶磷氮NMR光譜中的化學位移與偶合
常數。發現以環三偶磷氮的部分化學位移計算和預測出環三偶磷氮的化學
位移。而環三偶磷氮的偶合常數較化學位移不具規則。因此，偶合常數較
難分析。

關鍵字

相間轉移觸媒 ； 反應動力學 ； 偶磷氮 ； 取代反應

並列摘要

Organophosphazenes can be used as pressuried working fluids,
flame retardants and lubricant. Phase-transfer catalysis (PTC)
is considered a useful tool insynthesizing organic chemicals
from two immiscrible reaction. In the study ,phase-transfer
catalysis was carried out for the substitution reaction of
hexachlorocyclotriphosphazene ((NPCl2)3) and phenol in a
mulitphase system tosynthesize the partial (phenoxy)
chlorocyclotriphosphazene. The consumption of reactant and the
production of products is observed and studied during thecourse
of the reaction. There are three main topics which need to be
understood in studying the phase-transfer catalytic reaction,
including (i) the reactionrate in the organic phase, (ii)the
mass-transfer steps between the organic andaqueous phase , (iii)
the partition equilibrium of the catalysts between thetwo phase.
So the kinetics, mass-transfer effect and effect of
concentrationin each phase are discussed. Several rigid
conclusions were obtained:(1) Thereaction rate was dramatically
increasing by adding a small quantity ofphase-transfer catalyst.
The products of the partial (phenoxy) chlorocyclotriphosphazene
was separated by pressured column chromatograph and cooling
crystallization. On the basis of 31P NMR spectra ,the reaction
type belonging to a transion-nongeminal path. According to the
experimental data , the electronic effect and the steric effect
were empolyed to explain the reaction of an SN2 type of
mechanism. (2) Changing the initial concentration
ofhexachlorocyclotriphosphazene affected the value of pseudo-
first-orderreaction-rate constant. Hence, the reaction system
was controlled by both chemical-kinetics and mass-transfer
effects. The mass transfer of the catalyst between two phases
was investigated by a psedo-steady-state LLPTC model. Also, the
intrinsic reaction-rate constants of the series substitution and
the overall mass transfer coefficient of the catalyst from
organic phase to aqueous phase were determined by a combined
model. In addition, the corresponding energies,enthalpies and
entropies of activtion of the series substritution werealso
estimated.(3) Base on the experimental result, the relationship
between the functions of NaOH in a PTC reaction such as (i)
salting out the intermediateproduct of catalyst QY to the
organic phase and (ii)reducing the solvation between the
catalyst and water to improve the reactivity of active catalyst
in the organic phase,and the mass-transfer capability of the
catalyst between bothphases was clarified. (4) In order to
overcome the separating problem of the catalyst from the final
product ,the catalyst was immobilized on a polymer support,i.e.,
triphase catalyst .The polymer support is a copolymer of styrene
andchloromethylstyrene , using divinylbenzene as a crosslinking
agent. The masstransfer limitation influences the triphase
reaction rate. The particle diffusion and intrinsic reactivity
limit the displacement reaction in the organic phase. The film
diffusion of the aqueous phase limits in the ion-exchange step.
(5)In the present study, the NMR chemical shifts and
coupingconstant of cyclotriphosphazenes have been analyzed. I
found that chemical shift of cyclotriphosphazenes can be
calculated and predicted from partial chemical shift of
cyclotriphosphazenes.The coupling constant of
cyclotriphosphazenes are not regular than chemical shift.
Therefore, coupling constant difficult to be analysized in
synthesizing cyclotriphosphazenecompound.

並列關鍵字

Phase-transfer catalysis ； Reaction kinetic ； Phosphazene ； Sequential reaction