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Method for synthesis of aliphatic isocyanates from aromatic isocyanates

A technology of aromatic isocyanate and isocyanate, which is applied in the preparation of isocyanic acid derivatives, carbamate preparation, organic chemical methods, etc., can solve the problems of cost, output loss, catalyst passivation, etc.

Inactive Publication Date: 2004-06-02
EVONIK DEGUSSA GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantage is that lactam-blocked aromatic isocyanates dissociate back into isocyanate and lactam even at relatively low temperatures, which leads to yield loss and catalyst deactivation
For this, only rhodium-based catalysts are used in order to ensure low reaction temperatures, but they are very expensive since rhodium is more expensive than ruthenium

Method used

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  • Method for synthesis of aliphatic isocyanates from aromatic isocyanates
  • Method for synthesis of aliphatic isocyanates from aromatic isocyanates
  • Method for synthesis of aliphatic isocyanates from aromatic isocyanates

Examples

Experimental program
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Embodiment 1

[0118] has about 33m 2 Alumina shaped body (extrusion, d=3mm) with BET surface area and pore volume of 0.41ml / g bimodal pore distribution (extrusion, d=3mm) in which basically no pores with a diameter of 2-50nm were detected, while 100% of the pore volume Consisting of macropores with a diameter in the range of 50-10000nm, the alumina-shaped body is coated with an aqueous solution of ruthenium(III) nitrate at 90-100°C, in which the catalyst solution is sprayed on a movable carrier while the water is evaporated .

[0119] The catalyst solution has a concentration of 5% metal, based on the weight of the solution. The support coated in this way is heated at a temperature of 120-180 °C and subsequently treated with 50% H 2 and 50% of N 2 The mixture was reduced at 200 °C for 4 h. The catalyst prepared in this way contained 3% by weight of ruthenium, based on the total weight of the catalyst. The penetration depth of ruthenium is 70-90 μm. The ratio of the ruthenium surface a...

Embodiment 2

[0121] The composition is similar to the carrier of Example 1 and has about 32m 2 An alumina shaped body (extrudate, d=3 mm) with a BET surface area per g, a trimodal pore distribution and a pore volume of 0.58 ml / g was impregnated in a similar manner to Example 1. 31% of the pore volume of the support material consists of pores of 2-50 nm, 44% of pores of 50-10000 nm and 25% of pores with a pore diameter of more than 10000 nm to 5 μm. As in Example 1, the catalyst prepared in this way contained 3% by weight of ruthenium, and the penetration depth was 70-90 μm.

Embodiment 3

[0123] has about 54m 2 The alumina shaped body (extrudate, d=3 mm) of surface area per gram had a trimodal pore distribution and a pore volume of 0.77 ml / g. 40% of the pore volume consists of pores with a diameter of 2-50 nm and 60% is formed by pores with a diameter of 50-10000 nm. Impregnation of the carrier, calcination and reduction of the catalyst were carried out in the same manner as in Example 1. The catalyst prepared in this way contained 3% by weight of ruthenium, based on the total weight of the catalyst. Penetration depth is 70-90nm. The alumina forms used include α-, θ- and γ-Al 2 o 3 transform.

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Abstract

The invention relates to a method for synthesis of aliphatic isocyanates from aromatic isocyanates in substantially 3 stages. In particular, the invention relates to a method for synthesis of bis{4-isocyanatocyclohexyl}methane (H12MDI) from bis{4-isocyanatophenyl}methane (MDI). More especially, the invention relates to a method for synthesis of H12MDI with a trans-trans isomer content of <30%, preferably of <20%, particularly preferably of 5 to 15%.

Description

technical field [0001] The present invention relates to a process for the preparation of aliphatic isocyanates from aromatic isocyanates in essentially three steps. In particular, the present invention relates to the preparation of bis[4-isocyanatocyclohexyl]methane (H 12 MDI) approach. The invention relates in particular to preparations H having a trans-trans isomer content of <30%, preferably <20%, especially preferably 5-15%. 12 MDI method. Background technique [0002] The synthesis of isocyanates can be carried out by many different routes. For example, tetramethylxylylene diisocyanate (TMXDI) is a product of a typical isocyanate synthesis (US 4 130577) based on the reaction of an alkyl halide with a metal salt of isocyanuric acid. This method gives good yields, but the inevitable formation of metal chlorides is problematic. In addition, long reaction times must be accepted. Suitable laboratory-scale methods are in particular related to the azene-type rearra...

Claims

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Application Information

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IPC IPC(8): B01J23/46B01J35/04C07B61/00C07C263/04C07C263/16C07C265/10C07C265/14
CPCC07C263/04C07C265/10
Inventor S·科尔斯特鲁克M·克雷钦斯基C·莱特曼G·施托赫尼奥尔E·斯皮罗N·芬克R·罗莫尔德
Owner EVONIK DEGUSSA GMBH
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