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1,2-环己二醇合成新工艺研究
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摘要
“1,2—环己二醇合成新工艺的研究”是河南省杰出人才创新基金资助项目内容之一。本文针对国民经济发展的需求,结合我国精细化工行业的实际,进行了以环己烯为主要原料,合成1,2—环己二醇的研究。
     邻苯二酚是一个重要的精细化工产品,在医药、农药、香料、精细有机合成等众多领域有着广泛的应用。而1,2—环己二醇是制备邻苯二酚的一个重要的有机中间体。有关1,2—环己二醇的合成工艺,国内外文献报道很少,以环己烯、乙酸、过氧化氢为主要原料合成1,2—环己二醇的文献报道就更少。为此本文研究开发出了以环己烯、乙酸、过氧化氢为基本原料,采用原位法直接合成反式—1,2—环己二醇的新工艺路线。
     本文根据环己烯分子结构特点及有关单元合成反应的基础理论,首先制定出反式—1,2—环己二醇合成的初步实验方案,再借助于正交实验设计法等有关实验手段,用气相色谱仪采用内标法进行定量分析,并对得到的结果进行比较,确定了影响该复杂反应体系的关键因素:温度、静置时间、乙酸用量、过氧化氢用量、乙酸浓度。进而重点考察了温度、乙酸用量、过氧化氢用量、乙酸和乙酸酐比例对合成反应的影响。利用熔点测试、FTIR分析方法证实了本合成反应生成物确实是反式—1,2—环己二醇。
     在此基础上,采用人工神经网络技术,建立了预测最佳工艺条件的5—3—2—1结构的神经网络模型。当网络训练达到最优化时,14组实验数据网络输出值与实验值之间的相对误差的绝对值均小于1.78523%。14组数据的平均相对误差为0.5863%,不到1%。说明该模型能较好的逼近训练集样本的变化规律,可用于合成反应条件优化与预测。在此基础上优化得到了合成反式—1,2—环己二醇的最佳工艺条件(以0.1摩尔环己烯为基准):
     反应温度:40~45℃
     反应时间:≥90min
     静置时间:24h
     乙酸用量:1.2ml
     双氧水用量:0.13mol
    
     攀取次数:8
     并且利用神经网络模型进行了极限预测,其结果与上述优化实验
    条件非常接近。
     采用本文优化出的最佳工艺条件来合成反式一I,2一环己二醇,
    单程收率可达 74%,但是未反应的环己烯和乙酸以及摹取剂乙酸乙酯
    等都可以循环利用,因此,在这个实验里,选择性比转化率更重要,本
    反应的选择性用归一法化法计算达 95%以上。
     其次,对反式一1,2一环己二醇合成反应动力学也进行了探讨,
    得到的动力学方程为:
     dcp 399.84
     dl 107.87X2+1227二5X+3490.77
     QC
     一“·’”“环己烯“双氧水
     根据动力学模型,确定出最佳反应时间。同时,还研究了合成过
    程中过量乙酸和革取剂乙酸乙酯的回收利用问题。
     本工艺最大的优点有两点:
     (1)选择性高,儿乎没有副产物产生;
     (2)各物料可以实现全封闭循环,过量的乙酸和未反应的环己烯
    在蒸出后可以直接循环使用,荤取剂乙酸乙酯蒸出后也可以直接使
    用,中和用的氢氧化钠所生成的乙酸钠也可以作为中间产品,该工艺
    堪称为绿色环保工艺。
     综上所述,本文成功地开发出了以环己烯为主要原料,利用原位法
    直接合成反式一1,2一环己二醇的新工艺路线,并优化确定了较佳工
    艺条件,建立了合成反应动力学模型,从而为工程设计和工业化生产提
    供了一定的设计参数和理论依据.
The study of New Technology study of Synthesizing 1,2-cyclohexanediol" is one of subjects funded by Henan Outstanding Person Foundation. Aiming at demand of national economy and linking the actual condition of domestic refinery chemical , a routine with cyclohexene as main raw material was developed in the thesis.
    As a kind of impotant fine chemical product , O-dihydroxybenzene has a prosperous future in the field of medicine,pesticide,spice and fine organic synthesis. To prepare O-dihydroxybenzene with cyclohexene , trans-1.2- cyclohexanediol is a very important organic intermediate. Firstly, there is quite a few reports on the synthetic technology of trans- 1,2-cyclohexanediol in the country and the reports are even less about cyclohexene abroad. So thie thesis developed and obtained the new technology routine which adopts the original position method to synthesize 1,2-cyclohexanediol directly.
    At first, on the base of the formula structure of cyclohexene and correlative organic synthesis theory, we draw up the experimental scheme of the synthesis of trans-1.2-cyclohexanediol,. Then with the orthogonal design method and single-factor-experiment, analyzing with GC, the key factors affecting this complicate reaction were determined.,. Furthurmore we refocused the influence of temperature, acetic acid, hydrogen peroxide, the ratio of acetic acid and acetic anhydride. The ideal synthetic process conditions are acquired.
    On these bases, by means of the technology of artificial neural network, the 5-3-2-1 model of artificial neural network which is used to predict the optimal operation condition of the synthesis of cyclohexanediol was construced. With this model the error of experimental value and calculation value is only 1.78523% when it is fully optimized , it is made sure that this model is credible, so we could obtain the optimal synthesis reaction condition as follows:
    Taking cyclohexene O.lmol as base,
    temperature: 40~45℃;
    reaction time : >=90min;
    resting time after reaction: 24h;
    adding acetic acid : 1.2mol
    adding hydrogen peroxide: 0.13mol
    
    
    
    extraction times: 8
    In addition, we had a ultimate forecast, and its result was very close to the result of opitimal experiment.
    In this thesis, on the surface percentage yield is only 75 percent, but the unused acetic acid and ethyl acetate can be recycled. In addition, in this thesis the most pivotal is the selectivity, and not the percentage yield. The selectivity in this reaction is up to 96 percent calculated with unitary method.
    We studied the kinetics of the synthetic reaction of trans-1.2-cyclohexanediol and obtained the kinetic equation as folloes:
    
    Through the equation ,the best reaction time is obtained.
    This reaction will by-produce a lot of waste acid and ethyl acetate, this thesis also researched into their recycling problem.
    There are two outstanding advantages in this thesis. Firstly, the selectivity is very high, and little byproduct is abtained; Secondly, all materials can be circulatively used.
    In a word, in the thesis the optical processs condition of synthetic reaction of trans-1.2-cyclohexanediol was determined and the kinetic equation of the reaction was established. All these provide some design parameters and theoretical bases for the project design and Industrializing producing.
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