Preparation method of diphenyl cyclosiloxane

Abstract

The invention relates to a preparation method of diphenyl cyclosiloxane. In the method, high-purity diphenyl dimethoxysilane free of polychlorinated biphenyl and a small amount of water are adopted asraw materials, diether series compounds such as ethylene glycol diethyl ether and diethylene glycol dimethyl ether with normal-pressure boiling points higher than 100 DEG C are used as solvents, a trace amount of an organic alkali such as tetramethylammonium hydroxide is used as a catalyst, generated methanol is distilled off in a micro-boiling state in a reaction kettle with a rectifying column,and commercial diphenyl cyclosiloxane is obtained in one step. The generated powdery diphenyl cyclosiloxane is extremely easy to separate from the liquid, all solvents are completely recycled and used mechanically, the byproduct methanol can also be rectified and purified for application, and no wastewater is discharged in the whole process.

Description

technical field [0001] The invention relates to a method for preparing an organosilicon intermediate, in particular to a method for preparing a bisphenylcyclosiloxane with an environment-friendly process. [0002] Background of the invention [0003] Due to the structural characteristics of silicon and oxygen atoms, when the general organocyclosiloxane is formed, it is naturally formed by the interaction of silicon and oxygen elements to form cyclotrisiloxane, cyclotetrasiloxane, cyclopentasiloxane, and cyclohexasiloxane. Oxanes and complex isomeric states. For the siloxane with two phenyl groups connected to the silicon atom, this rule is also followed when forming the ring body - that is to say, its composition is composed of hexaphenylcyclotrisiloxane (hereinafter referred to as "P3" refers to), octaphenylcyclotetrasiloxane (hereinafter referred to as "P4"), decaphenylcyclopentasiloxane (hereinafter referred to as "P5"), and P4, P5 also has two structures of "boat type" ...

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Problems solved by technology

[0013] 2. Due to the different times, in the above-mentioned patents or articles, there is no mention of the persistent harmfulness of polychlorinated biphenyls (hereinafter referred to as "PCBs") introduced by various raw materials, but the world today is very concerned about PCBs. Represents extremely strict restrictions on persistent harmful pollutants (the EU RoHS recommended inspection items continue to increase)

[0015] 3. The cost of diphenylsilanediol that meets the requirements is high, and half of the synthesized Pn products are linear cold polymers, which are difficult to purify by recrystallization, so the yield of Pn is too low

[0017] 5. Special emphasis should be placed on the method mentioned in the Chinese expired patent CN1096467C, which has insurmountable shortcomings: 1. Since the invention uses a substance with a generally low boiling point as a solvent, in the production process with a slightly larger batch, there are obvious The magnification effect of the concentrated and violent exothermic phenomenon leads to the boiling of the solvent, which brings great hidden dangers to production safety.

Two, because the solvent used has solubility to Pn and its by-product, the selectivity to target product is not strong, so the product purity that obtains is not high, and crystal is wrapped in the viscous linear body material, even crystal purity is not high Only 80% is above, and the Pn yield actually obtained by recrystallization is not higher than 50%

3. Since this patent uses diphenyldihalosilane as the starting material, hydrochloric acid treatment during alcoholysis, solvent recovery, wastewater discharge, PCBs, etc., there are many steps, and the production operation is very difficult

[0018] With the increasing requirements of domestic industrial upgrading, Pn produced by traditional processes has more or less quality problems, or the processing steps are complicated, or there are a large number of by-products, or the emission exceeds the standard, which brings environmental protection pressure.

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