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Process for the preparation of diisocyanates by phosgenation of diamine suspensions

A technology of aniline diisocyanate and tetralin diisocyanate is applied in the field of preparing diisocyanate by phosgenation of diamine suspension, and can solve the problems of cost, slow reaction of amine hydrochloride, increase of reaction volume and the like

Active Publication Date: 2020-10-23
COVESTRO DEUTSCHLAND AG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The method has the disadvantage that the reaction of amine hydrochloride with phosgene is very slow
The required reaction volume is thus increased, which affects the outlay for constructing the corresponding device
Furthermore, liquefied hydrogen chloride is required for the preparation of amine hydrochloride, which means increased costs for compressing and liquefying the hydrogen chloride
A particular disadvantage is that it has to work at very high pressures from 10 to 60 bar
Another important disadvantage is that the method is not economical because it has to work through two stages

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0067] Example 1 (comparative example): Preparation of a suspension of 1,5-naphthalene diisocyanate (1,5-NDA) using a paddle stirrer

[0068] Under a nitrogen atmosphere, a suspension was prepared from 50 g of powdered solid 1,5-NDA and 150 g of dry chlorobenzene (MCB) by stirring with a paddle stirrer at 400 rpm for 10 min. The particle size distribution obtained is reported in Table 1 (particle size measurement by means of laser diffraction according to ISO 13320).

Embodiment 2

[0069] Example 2 (according to the invention): Preparation of a suspension of 1,5-NDA using Ultra-TURRAX

[0070] Under a nitrogen atmosphere, 50 g of powdered solid 1,5-NDA and 150 g of dry chlorobenzene (MCB) were passed through Ultra-TURRAX (rotor-stator-system, ie gear-tooth disperser) at 10000 rpm Stir for 1 min to prepare a suspension. The particle size distribution obtained is reported in Table 1 (particle size measurement by means of laser diffraction according to ISO 13320).

[0071] Table 1: Particle size distribution in Examples 1 and 2

[0072] distributed Example 1: Paddle stirrer [µm] Example 2: Ultra-TURRAX [µm] Particle size reduction in Example 2 compared to Example 1 D (0.06) 40.7 30.9 24% D (0.10) 52.8 40.4 23% D (0.15) 64.9 50.4 22% D (0.20) 75.9 59.7 21% D (0.30) 97.1 78.1 20% D (0.50) 144.9 121.6 16% D (0.85) 321.0 291.9 9% D (0.90) 383.5 352.3 8%

[0073] Thus, depending on t...

Embodiment 3

[0074] Example 3 (comparative): Phosgenation of a 1,5-NDA suspension prepared using a paddle stirrer

[0075] A solution of 120 g of phosgene in 300 g of chlorobenzene was prepared at 0° C. in a phosgenation plant, wherein the phosgene was condensed from a compressed gas bottle into the chlorobenzene. A suspension of 50 g of technical grade 1,5-diaminonaphthalene (purity 99.2% according to GC) prepared according to Example 1 in 150 g of chlorobenzene was added in one pour with stirring . Subsequently, the reaction mixture was heated to reflux over the course of 120 min with continuous feeding of gaseous phosgene (approximately 5-10 l / h) from a compressed gas cylinder and maintained at reflux for 10 h. Excess phosgene was then removed, phosgene and part of the chlorobenzene being distilled off in a water-jet vacuum. Afterwards, the mixture was fractionally distilled in vacuo. The yield of 1,5-naphthalene diisocyanate (1,5-NDI) was 75.6% of the theoretical value.

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Abstract

The present invention relates to a process for the preparation of diisocyanates by phosgenation of diamine suspensions. In particular, a subject of the invention is a process for the preparation of organic diisocyanates by reacting the corresponding diamines with phosgene in an inert solvent. A high-melting diamine selected from the group consisting of 1,5-naphthalene diamine, tetrahydronaphthalene diamine, 1,4-phenylene diamine, durene diamine and di-o-toluidine diamine is used as diamine. According to the invention, a suspension of said diamine is prepared in an inert solvent, using a dynamic mixing device selected from a disc disperser and a rotor-stator-system, and the suspension obtained is phosgenated.

Description

[0001] This patent application is a divisional application of a patent application with the same title with the Chinese patent application number 201380049612.3 and the filing date being September 18, 2013. technical field [0002] A subject of the present invention is a process for the preparation of organic diisocyanates by reacting the corresponding diamines with phosgene in an inert solvent. A high-melting diamine selected from the group consisting of 1,5-naphthalene diamine, tetrahydronaphthalene diamine, 1,4-phenylene diamine, durene diamine and di-o-toluidine diamine is used as diamine. According to the invention, a suspension of the diamine is prepared in an inert solvent, using a dynamic mixing device selected from the group consisting of a disc disperser (Dispergierscheibe) and a rotor-stator system, and the suspension obtained is phosgenated. Background technique [0003] Diisocyanates are produced in large quantities and are mainly used as starting substances for...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C263/10C07C265/14
CPCC07C2602/10C07C263/10C07C265/14
Inventor J.劳厄C.斯蒂芬斯J.克劳泽S.韦斯霍芬W.基利安M.泽坎普M.鲁兰
Owner COVESTRO DEUTSCHLAND AG
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