# US 10,370,767 B2 · Process for preparing alcohols by electrochemical reductive coupling

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- Number: US 10,370,767 B2
- Document ID: US10370767B2
- Status: Granted
- Kind: B2
- Application number: 15/503,459
- Filed: 2015-08-12
- Published: 2017-08-17
- Granted: 2019-08-06
- Earliest claimed: 2014-08-14
- Assignees: BASF SE
- Applicants: BASF SE
- Inventors: Nicola Christiane Aust; Ulrich Griesbach; Ralf Pelzer; Thomas Haag; Ulrich Berens; Jörg Botzem
- Web page: https://patentgrep.com/patent/US10370767B2

## CPC

- C25B 3/29: Coupling reactions
- C25B 3/07: Oxygen containing compounds
- C25B: ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR (anodic or cathodic protection C23F13/00; single-crystal growth C30B)

## Abstract

Alcohols are prepared by electrochemical reductive coupling of an aromatic vinyl compound and a carbonyl compound in a process which comprises electrolyzing an electrolyte solution in an electrochemical cell, the electrolyte solution comprising the aromatic vinyl compound, the carbonyl compound and a non-aqueous protic solvent, such as methanol, wherein the electrolyte solution is in contact with a carbon-based cathode. Styrene is reacted with acetone to prepare 2-methyl-4-phenyl-2-butanol.

## Claims

### Claim 1

A process for preparing an alcohol by electrochemical reductive coupling, the process comprising providing an electrolyte solution comprising an aromatic vinyl compound, a carbonyl compound, and a non-aqueous protic solvent in an electrochemical cell, and electrolyzing the electrolyte solution in the cell, wherein the electrolyte solution is in contact with a carbon-based cathode; and
wherein the electrolyte solution contains less than 5% by weight of water.

### Claim 2 (depends on 1)

The process of claim 1, wherein the non-aqueous protic solvent is an alcohol.

### Claim 3 (depends on 2)

The process of claim 2, wherein the non-aqueous protic solvent is methanol.

### Claim 4 (depends on 1)

The process of claim 1, wherein the carbon-based cathode is selected from the group consisting of a graphite electrode, a gas diffusion layer electrode, a carbon felt electrode and a graphite felt electrode.

### Claim 5 (depends on 1)

The process of claim 1, wherein the anode is a carbon-based anode.

### Claim 6 (depends on 5)

The process of claim 5, wherein the carbon-based anode is selected from the group consisting of a graphite electrode, a gas diffusion layer electrode, a carbon felt electrode and a graphite felt electrode.

### Claim 7 (depends on 1)

The process of claim 1, wherein the electrolyte solution comprises a conducting salt.

### Claim 8 (depends on 7)

The process of claim 7, wherein the conducting salt is a quaternary ammonium salt.

### Claim 9 (depends on 1)

The process claim 1, wherein the electrolyte solution comprises a stable radical compound.

### Claim 10 (depends on 9)

The process of claim 9, wherein the stable radical compound is a nitroxyl radical.

### Claim 11 (depends on 10)

The process of claim 10, wherein the stable radical compound is (2,2,6,6-tetramethyl-piperidin-1-yl)oxyl or 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl.

### Claim 12 (depends on 1)

The process of claim 1, wherein the carbonyl compound is a ketone.

### Claim 13 (depends on 1)

The process of claim 1, wherein the prepared alcohol is 2-methyl-4-phenyl-2-butanol, the aromatic vinyl compound is styrene, and the carbonyl compound is acetone.

### Claim 14 (depends on 13)

A process of making 2-methyl-4-cyclohexyl-2-butanol by hydrogenation of the 2-methyl-4-phenyl 2-butanol prepared from the process of claim 13.

### Claim 15

A process for preparing an alcohol by electrochemical reductive coupling, the process comprising providing an electrolyte solution including an aromatic vinyl compound, a carbonyl compound, a nitroxyl compound, a conducting salt, and a non-aqueous protic solvent in an electrochemical cell, and electrolyzing the electrolyte solution in the cell, wherein the electrolyte solution is in contact with a carbon-based cathode selected from the group consisting of a graphite electrode, a gas diffusion layer electrode, a carbon felt electrode and a graphite felt electrode;
wherein the electrolyte solution contains less than 5% by weight of water.

### Claim 16 (depends on 15)

The process of claim 15, wherein the carbonyl compound is a ketone, and the aromatic vinyl compound is styrene.

### Claim 17 (depends on 16)

The process of claim 16, wherein the carbonyl compound is acetone, and the prepared alcohol is 2-methyl-4-phenyl-2-butanol.

### Claim 18 (depends on 17)

The process of claim 17, wherein the selectivity to 2-methyl-4-phenyl-2-butanol is in a range from 45% to 70%, based on conversion of the styrene.

### Claim 19 (depends on 17)

2-methyl-4-cyclohexyl-2-butanol prepared by hydrogenation of the 2-methyl-4-phenyl-2-butanol prepared from the process of claim 17.