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翻译自

Baur K G, Brunner E, Brandt E. Preparation of 3-chlorophthalic anhydride: U.S. Patent 5,683,553[P]. 1997-11-4.

Baur K G，Brunner E，Brandt E. 3-氯邻苯二甲酸酐的制备：美国专利5,683,553 [P]。 1997-11-4。

ABSTRACT

A process for preparing essentially pure 3-chlorophthalic anhydride from a mixture in which 3-chlorophthalic anhydride is present in addition to 4,5-dichlorophthalic anhydride, which involves first distilling off a mixture of 3-chlorophthaiic anhydride and 4,5-dichlorophthalic anhydride, so that the obtained bottoms is essentially free of 4,5-dichlorophthalic anhydride, and then by distillation of the obtained bottoms, recovering 3-chlorophthalic anhydride in a second distillation step. The starting mixture is preferably prepared without solvent in a melt by incomplete chlorination of phthalic anhydride using FeCl3 as a catalyst.

摘要

除了4，5-二氯邻苯二甲酸酐外还存在3-氯邻苯二甲酸酐的混合物制备纯的3-氯邻苯二甲酸酐的方法，首先要蒸馏出3-氯邻苯二甲酸酐和4,5-二氯邻苯二甲酸酐的混合物，使所得的塔底物基本上不含4，5-二氯邻苯二甲酸酐，然后通过蒸馏所得的塔底物，在第二蒸馏步骤中回收3-氯邻苯二甲酸酐。优先选用FeCl₃作为催化剂对邻苯二甲酸酐进行不完全氯化可使熔融物中不添加溶剂的情况下制备起始混合物。

PREPARATION OF 3-CHLOROPHTHALIC ANHYDRIDE

SUMMARY OF THE INVENTION

The present invention relates to a process for preparing essentially pure 3-chlorophthalic anhydride from a mixture in which 3-chlorophthalic anhydride is present in addition to 4,5-dichlorophthalic anhydride.

3-氯邻苯二甲酸酐的制备

发明概要

本发明涉及一种从含有3-氯邻苯二甲酸酐和4-5-二氯邻苯二甲酸酐的混合物中制备纯的3-氯邻苯二甲酸酐的方法。

BACKGROUND OF THE INVENTION

On account of their reactivity, monochlorinated phthalic anhydrides are sought-after intermediates, for example for preparing heterocycles, as dye precursors and recently also for preparing polymers. For these intended uses they are usually needed in high purity. While the preparation of 4-chlorophthalic anhydride in a simple manner in high yield by chlorination with sodium hypochlorite has been disclosed (GB Patent 628401, cf. also E. E. Ayling, J. Chew. Soc.(1929), 253), the preparation of pure 3-chlorophthalic anhydride is difficult.

发明背景

由于它们的活泼性，单氯代邻苯二甲酸酐是很受欢迎的中间体，例如用于制备杂环和作为染料的原料，最近还用于制备聚合物。对于这些可预见的用途，它们通常需要很高的纯度。虽然已经公开了用次氯酸钠氯化法简单高效地制备4-氯邻苯二甲酸酐（GB专利628401，另请参见E. E. Ayling，J. Chew。Soc。（1929），253），但是制备纯的3-氯邻苯二甲酸酐是困难的。

Pare 3-chlorophthalic anhydride can be obtained by oxidation of 3-chloro-o-xylene, for example with nitric acid at elevated temperature and elevated pressure and subsequent conversion to the anhydride of the 3-chlorophthalic acid formed in the oxidation. The isomerically pure 3-chloro-oxylene is obtained by distillative separation of the products of the nuclear chlorination of o-xylene, but this distillative separation is extremely complicated because of the low boiling point differences (relative volatilities) of 3- and 4-chloro-o-xylene. An industrial column for the simultaneous preparation of 3-chloro-o-xylene and 4-chloro-oxylene in parities of, in each case, above 990k needs, in the case of continuous operation, approximately 250 theoretical separation stages. Other separation processes for separating the isomers, such as fractional crystallization, are no less complicated.

3-氯邻苯二甲酸酐是通过3-氯邻二甲苯氧化得到的，例如在高温高压下用硝酸氧化，然后在氧化过程中形成3-氯邻苯二酸酐。同分异构体纯3-氯-邻二甲苯是通过对邻二甲苯氯化反应得到的，但由于3-和4-氯-邻二甲苯的沸点差(相对挥发分)极低，这种蒸馏分离极为复杂。在连续操作的情况下，用于同时制备3-氯邻二甲苯和4-氯邻二甲苯的工业塔在不同情况下均高于990k，需要约250个理论分离级。 用于分离异构体的其他分离方法，例如分步结晶，也同样复杂。

3-Chlorophthalic anhydride can also be prepared from 3-nitrophthalic anhydride by replacement of the vitro group by chlorine. The 3-nitrophthalic anhydride needed for this is prepared in three process steps by nitration of phthalic anhydride in moderate yield, by isomer separation of the nitrophthalic acids formed, by fractional crystallization and by conversion to the anhydride of the 3-nitrophthalic acid obtained（M.S. Newman, P.G. Scheurer, 7. Am. Chew. Soc. 78 (1956), 5005; Organic Syntheses, Coil. Vol. 1 (1932), 399-401). This multistage and complicated route, which additionally gives poor yields, is not very suitable for industrial use.

以3-硝基邻苯二甲酸酐为原料，用氯取代离体基团制备3-氯代邻苯二甲酸酐。所需要的3-硝基邻苯二甲酸酐是通过3个步骤来制备的，这3个步骤分别是邻苯二甲酸酐的硝化反应，形成的硝基邻苯二甲酸酐的异构体分离反应，分步结晶反应和3-硝基邻苯二甲酸酐的转化反应。(M.S. Newman, P.G. Scheurer, 7. Am. Chem. Soc. 78 (1956), 5005; Organic Syntheses, Coil. Vol. 1 (1932), 399-401) 这种多级且复杂的路线，还会导致收率低下，因此不太适合工业应用。

The simplest synthesis of the monochlorinated phthalic anhydrides, namely the chlorination of phthalic anhydride using Lewis acid catalysts, leads, only with very low conversions, to mixtures which only contain the two isomerit 3- and 4-chlorophthalic anhydrides which are separable by distillation; as soon as the conversion rates reach economically acceptable values, more highly chlorinated phthalic anhydrides are always also formed (A.Zweig and M. Epstein, 1. Org. Chew. 43 (1978), No. 19, pages 3690-3692). According to the present state of knowledge, recovery of essentially pure 3-chlorophthalic anhydride from this mixture under economically acceptable conditions, ie. by distillative separation or another process which can be carried out on a large scale, did not appear possible.

一氯化邻苯二甲酸酐最简单的合成方法，即使用路易斯酸催化剂氯化邻苯二甲酸酐，其转化率极低，只含有两种异构的3-和4-氯化邻苯二甲酸酐，可通过蒸馏分离;一旦转化率达到经济上可接受的值，就会生成更多的高氯化邻苯二甲酸酐(A.Zweig and M. Epstein, 1. Org. Chew. 43 (1978), No. 19, pages 3690-3692)。根据目前的知识，在经济上可以接受的条件下，从这种混合物中回收纯的3-氯邻苯二甲酸酐。通过蒸馏分离或其他可以大规模进行的方法，似乎是不可能的。

The difficulty in the distillative separation of the product mixture of a chlorination of phthalic anhydride using Lewis Acid catalysts lies in the separation of 3-chlorophthalic anhydride and 4,5-dichlorophthalic anhydride, which according to the literature has exactly the same boiling points, 313 ℃ at normal pressure. A. Zweig and M. Epstein, loc. cit., were only able to obtain mixtures of these two chlorination products.

利用路易斯酸做催化剂后分离邻苯二酸酐氯化反应产物混合物的难点在于3-氯邻苯二甲酸酐与4,5-二氯邻苯二甲酸酐的分离，A. Zweig and M. Epstein的文献报道二者沸点完全相同，常压下为313℃。只能得到这两种氯化产物的混合物。

Table I below gives a survey of the boiling points at normal pre

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