Catalytic hydrogenation process for the synthesis of terminal diols from terminal dialkyl aliphatic esters

Patent metadata

Field	Value
Publication number	US-9944579-B2
Application number	US-201615544243-A
Country	US
Kind code	B2
Filing date	Jan 15, 2016
Priority date	Jan 15, 2015
Publication date	Apr 17, 2018
Grant date	Apr 17, 2018

Abstract

A phosphorus ligand-free, mild, efficient and complete catalytic hydrogenation process is for the sustainable production of terminal diols from renewable terminal dialkyl esters with improved yield. Soluble, phosphorus ligand free Ru (II)-pincer type complexes can be used as catalysts in the hydrogenation process.

First claim

We claim:

1. A catalytic hydrogenation process for synthesis of terminal diols starting from terminal dialkyl aliphatic esters, comprising, stirring a reaction mixture of phosphorus free catalyst, potassium tert-butoxide ( t BuOK), terminal dialkyl aliphatic esters and toluene at temperature of 110° C. for a period in the range of 22 to 24 hr under H 2 pressure, wherein said catalyst is selected from the group consisting of HCl(CO)Ru( isoPr SNS) (2), HCl(CO)Ru( Ph SNS) (4), and HCl(CO)Ru( Et SNS) (5), represented by the formula

2. The process as claimed in claim 1 , wherein said terminal dialkyl aliphatic ester is selected from the group consisting of dialkyl oxalate, dialkyl malonate, dialkyl succinate, diethyl glutarate and dialkyl adipate, wherein alkyl groups in said terminal dialkyl aliphatic ester is linear or branched.

3. The process as claimed in claim 1 , wherein said terminal diol is selected from the group consisting of ethane-1,2-diol, propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, and hexane-1,6-diol.

4. The process as claimed in claim 1 , wherein a yield of said terminal diols is in the range of 35-70%.

5. A phosphorus-free catalyst of formula 4:

6. A process for the preparation of phosphorus free catalyst selected from the group consisting of HCl(CO)Ru( isoPr SNS) (2), HCl(CO)Ru( Ph SNS) (4), and HCl(CO)Ru( Et SNS) (5), represented by the formula

wherein said process comprises:
(a) adding a methanolic solution of sodium thiolate compound and potassium hydroxide (KOH) to a solution of bis (2-chloroethyl)amine hydrochloride in methanol followed by stirring for 12 to 14 hrs at 30° C. to afford corresponding SNS compounds; and
(b) refluxing the reaction mixture of compound of step (a), RuHCl(CO)(PPh 3 ) 3 and o-xylene at temperature ranging from 140 to 150° C. for a period ranging from 1 to 2 hr under argon atmosphere to yield Ru (II)-pincer type SNS complexes.

7. The process as claimed in claim 6 , wherein said sodium thiolate compound is selected from the group consisting of sodium-2-propanethiolate, sodium thiophenolate and sodium ethanethiolate.

8. The process as claimed in claim 6 , wherein said SNS compounds are selected from the group consisting of bis (2-(phenylthio) ethyl) amine [ Ph SNS] (3), bis(2-(isopropylthio)ethyl)amine [ isoPr SNS] (1) and bis (2-(ethylthio) ethyl) amine [ Et SNS].

9. The process as claimed in claim 6 , wherein said Ru (II)-pincer type SNS complexes is selected from the group consisting of HCl(CO)Ru( isoPr SNS) (2), HCl(CO)Ru( Ph SNS) (4), and HCl(CO)Ru(Et-SNS) (5).

Assignees

• Council Scient Ind Res

Inventors

• Balaraman Ekambaram
• Sahoo Manoj Kumar

Classifications

• C07C29/149 Primary

  with hydrogen or hydrogen-containing gases · CPC title

• B01J31/226

  Sulfur, e.g. thiocarbamates · CPC title

• B01J2231/641

  Hydrogenation of organic substrates, i.e. H2 or H-transfer hydrogenations, e.g. Fischer-Tropsch processes · CPC title

• B01J2531/821

  Ruthenium · CPC title

• B01J31/1805

  the ligands containing nitrogen · CPC title