# US 10,479,762 B1 · Zwitterionic surfactant containing ethoxylate units

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- Number: US 10,479,762 B1
- Document ID: US10479762B1
- Status: Granted
- Kind: B1
- Application number: 16/269,218
- Filed: 2019-02-06
- Granted: 2019-11-19
- Earliest claimed: 2019-02-06
- Assignees: King Fahd University of Petroleum and Minerals
- Applicants: King Fahd University of Petroleum and Minerals
- Inventors: Syed M. Shakil Hussain; Muhammad Shahzad Kamal
- Web page: https://patentgrep.com/patent/US10479762B1

## CPC

- C07C 303/32: of salts of sulfonic acids
- C07C 309/14: containing amino groups bound to the carbon skeleton
- C09K 8/584: characterised by the use of specific surfactants
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE

## Abstract

Zwitterionic surfactants having a sulfonate head group and an ethoxylated alkyl tail. A method for synthesizing the surfactants via amidation of an ethoxylated carboxylic acid and an amine catalyzed by a fluoride salt as well as a sulfonation reaction using a sultone is provided.

## Claims

### Claim 1

A surfactant of formula (I)
or a tautomer thereof, or a stereoisomer thereof;
wherein:
R1 and R2 are independently selected from the group consisting of a hydrogen, an optionally substituted alkyl, and an optionally substituted cycloalkyl;
R3 and R4 are independently selected from the group consisting of an optionally substituted alkyl, and an optionally substituted cycloalkyl;
n is an integer in a range of 1-15;
x is an integer in a range of 5-21;
y is an integer in a range of 2-5; and
z is an integer selected from 3 and 4.

### Claim 2 (depends on 1)

The surfactant of claim 1, wherein R1 and R2 are independently selected from the group consisting of a hydrogen and a methyl.

### Claim 3 (depends on 1)

The surfactant of claim 1, wherein R1 and R2 are a hydrogen.

### Claim 4 (depends on 1)

The surfactant of claim 1, wherein R3 and R4 are independently selected from the group consisting of a methyl, an ethyl, and an isopropyl.

### Claim 5 (depends on 1)

The surfactant of claim 1, wherein R3 and R4 are a methyl.

### Claim 6 (depends on 1)

The surfactant of claim 1, wherein n is an integer in a range of 2-10.

### Claim 7 (depends on 1)

The surfactant of claim 1, wherein x is an integer in a range of 11-13.

### Claim 8 (depends on 1)

The surfactant of claim 1, wherein y is 3.

### Claim 9 (depends on 1)

The surfactant of claim 1, which has a formula (II)
wherein:
n is an integer in a range of 1-15; and
x is an integer in a range of 11-13.

### Claim 10 (depends on 1)

The surfactant of claim 1, which has a number average molecular weight of 500-1,500 g/mol.

### Claim 11 (depends on 1)

A method of synthesizing the surfactant of claim 1, the method comprising:
mixing a carboxylic acid of formula (III)
or a salt thereof with an amine of formula (IV)
or a salt thereof, or a stereoisomer thereof in the presence of a fluoride salt to form a mixture;
heating the mixture to obtain an intermediate; and
reacting the intermediate with a sultone of formula (V)
or a salt thereof in a solvent to form the surfactant,
wherein:
R1 and R2 are independently selected from the group consisting of a hydrogen, an optionally substituted alkyl, and an optionally substituted cycloalkyl;
R3 and R4 are independently selected from the group consisting of an optionally substituted alkyl, and an optionally substituted cycloalkyl;
n is an integer in a range of 1-15;
x is an integer in a range of 5-21;
y is an integer in a range of 2-5; and
z is an integer selected from 3 and 4.

### Claim 12 (depends on 11)

The method of claim 11, wherein the carboxylic acid of formula (III) has a number average molecular weight of 300-800 g/mol.

### Claim 13 (depends on 11)

The method of claim 11, wherein the amine of formula of (IV) is 3-(dimethylamino)-1-propylamine.

### Claim 14 (depends on 11)

The method of claim 11, wherein the sultone of formula (V) is 1,3-propanesultone.

### Claim 15 (depends on 11)

The method of claim 11, wherein a molar ratio of the amine of formula (IV) to the carboxylic acid of formula (III) is in a range of 1:1 to 5:1.

### Claim 16 (depends on 11)

The method of claim 11, wherein the mixture further comprises a molecular sieve.

### Claim 17 (depends on 16)

The method of claim 16, wherein the molecular sieve comprises aluminum oxide.

### Claim 18 (depends on 11)

The method of claim 11, wherein the fluoride salt is sodium fluoride.

### Claim 19 (depends on 11)

The method of claim 11, wherein the mixture is heated at a temperature of 100-200° C.

### Claim 20 (depends on 11)

The method of claim 11, wherein the reacting is conducted at a temperature of 50-100° C.