Liquid phase nitration of aromatics using solid acid catalyst

Patent metadata

Field	Value
Publication number	US-2016145191-A1
Application number	US-201414895867-A
Country	US
Kind code	A1
Filing date	Jun 3, 2014
Priority date	Jun 3, 2013
Publication date	May 26, 2016
Grant date	—

Abstract

The present invention discloses an improved process for the liquid phase nitration of aromatic compounds catalyzed by WO3 supported on mesoporous silica support, at low temperature, with high conversion and selectivity.

First claim

1 . A liquid phase nitration of aromatic compounds using solid acid catalyst and the said process comprising the steps of:
i. refluxing a solution of aromatic compound and the solid acid catalyst in an organic solvent under nitrogen atmosphere at a temperature in the range of 80-110° C. for period in the range of 2 to 10 hr followed by drop wise addition of 30-98% HNO 3 preferably 70% with the removing of the water formed during the reaction azeotropically.

2 . The process according to claim 1 , wherein solid acid catalyst used is tungsten oxide (WO 3 ) supported on mesoporous silica having BET surface area in the range of 367 to 397 M 2 /g.

3 . The process according to claim 1 , wherein the aromatic compound is selected from monocyclic or polycyclic aromatic compounds such as benzene, xylene, toluene, naphthalene, phenanthrene, phenols or heteroaryls.

4 . The aromatic compounds are selected from monocyclic or polycyclic aromatic compounds which may be monosubstituted or polysubstituted by, for example, nitro, nitroso, halogen, hydroxyl, alkoxy, aryloxy, carboxyl, alkylcarbonyloxy, arylcarbonyloxy, acylamino, alkylsulfonyl, arylsulfonyl, alkylsulfoxyl, arylsulfoxyl, sulfo, cyano and/or C1-C17 alkyl groups, preferably by nitro, halogen, cyano and/or C1-C17 alkyl groups. Amino, alkylamino or dialkylamino groups, low-valency sulfur-or phosphorus-containing substituents and other readily oxidizable or nitratable groups are unsuitable for the purposes of a selective nitration of the aromatic ring. Preferred aromatic hydrocarbons are unsubstituted or substituted benzene, xylenes, toluene, naphthalene, phenols, biphenyl, anthracene and phenanthrene, heteroarysl.

5 . The process according to claim 1 , wherein the catalyst is used in the molar ratio of 0.009 to 0.1 per mole of the aromatic compound used.

6 . The process according to claim 1 , wherein the organic solvent is selected from solvents with a boiling point in the range of 80-110° C. such as acetonitrile, 1,2 dichloroethane or dioxane.

7 . A sol-gel process for preparation of the solid acid catalyst as claimed in claim 1 , comprising the steps of:
i. mixing silica-40 and C1 to C6 alcohol with stirring for a period in the range of 1 to 3 hr to obtain a solution; ii. adding drop wise aqueous metatungstate salt solution in the solution as obtained in step (i); iii. stirring the mixture as obtained in step (ii) for a period in the range of 1 to 3 hr followed by addition of 2-10% ammonium hydroxide solution to obtain a white gel; iv. drying the gel as obtained in step (iii) for period in the range of 2 to 24 hr followed by calcining for period in the range of 2 to 6 hr at temperature in the range of 450 to 500° C. at the rate of 5° C. per min to obtain the solid acid catalyst.

8 . The sol-gel process according to claim 6 , wherein the metatungstate salt is selected from alkali, alkaline earth metals or ammonium meta tungusted salt.

9 . The sol-gel process as claimed in claim 7 further comprises:
i. reacting the solution of tungstic acid in water with 45 to 55% aq. hydrogen peroxide followed by addition of 20 to 30% ammonia to obtain a solution;
ii. Adding drop wise solution of step (i) to a mixture of silica-40 and C1 to C6 alcohol, stirring, adding 2-10% ammonia to obtain a white gel; and
iii. drying and calcining at about 500° C. to yield the desired product.

Assignees

• Council Scient Ind Res

Inventors

• Umbarkar Shubhangi Bhalchandra
• Dongare Mohan Keraba
• Biradar Ankush Venkatrao
• Kulal Atul Balasaheb
• Kotbagi Trupti Vyankatesh
• Bhosale Ashvini Ramesh
• Chandgude Macchindra Gulabrao

Classifications

• B01J21/08

  Silica · CPC title

• B01J23/30

  Tungsten · CPC title

• B01J37/0236

  Drying, e.g. preparing a suspension, adding a soluble salt and drying · CPC title

• B01J37/04

  Mixing {(B01J37/0009, B01J37/0018 take precedence)} · CPC title

• C07B43/02

  of nitro or nitroso groups · CPC title