Process for preparing esterquats

Details Process for preparing esterquats Process for preparing esterquats

2000-07-19

2002-04-30

Carr, Deborah D. (Department: 1621)

C554S110000, C564S295000, C564S296000

Reexamination Certificate

active

06379294

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to a process for preparing an esterquat, compositions comprising said esterquat, and the use of said compositions as a gas hydrate growth inhibitor.
BACKGROUND OF THE INVENTION
Gas hydrate crystals (clathrates of gases in a lattice consisting of water molecules) are formed in natural gas and crude oil by the interaction of low-boiling hydrocarbons, such as methane, ethane, propane, butane, and isobutane, and water under conditions of elevated pressure and reduced temperature. It has been known for a long time that gas hydrate crystals when allowed to form and grow inside a conduit such as a pipeline, tend to block or even damage the conduit. A number of methods have been suggested to prevent such blocking, of which the use of a crystal growth inhibitor is considered to be very attractive.
Various types of gas hydrate growth inhibitors are known in the art and at present preference is given to quaternary ammonium compounds (i.e. quats) due to their high efficiency. Preferred compounds contain at least one ester function in order to improve the biodegradability of the quat and such compounds are referred to as esterquats. A particularly interesting class of esterquat gas hydrate growth inhibitors are diesterquats.
WO 99/13197 relates to a method for inhibiting the plugging of a conduit by gas hydrates wherein use is made of a quaternary ammonium gas hydrate growth inhibitor. Diesters of dibutyl diisopropanol ammonium bromide and coconut fatty acid and of dibutyl diisobutanol ammonium bromide and coconut fatty acid are described. These diesterquats are prepared, e.g., by quaternizing dibutyl isopropanol amine with propylene oxide and hydrogen bromide in isopropanol, followed by acylation of the dibutyl diisopropanol ammonium bromide formed with coconut fatty anhydride.
Disadvantages of this process are that it proceeds in a low yield, that it requires the use of special equipment, that it uses a solvent, which needs to be removed, and that it uses coconut fatty anhydride, which is not readily available. A further drawback is that during the esterification one equivalent of coconut fatty acid is formed, which needs to be recycled. For these reasons, the process of WO 99/13197 is less attractive economically.
WO 96/34177 discloses the diester of dibutyl diethanol ammonium bromide and coconut fatty acid in Experiment A 2b and the diester of dibutyl diethanol ammonium chloride and tallow fatty acid in Experiment A 3b, but without giving experimental details on the preparation thereof (see page 6, lines 15-18 of WO 96/34177). These diesterquats are used for inhibiting the plugging of conduits by gas hydrates.
U.S. Pat. No. 5,523,433 discloses a process for preparing dialkyl diacyloxyalkyl ammonium compounds in which an alkyl dialkanol amine such as methyl diethanol amine is first esterified with a C
12
-C
22
fatty acid in the presence of an acid having a pK
a
of below 5 such as hypophosphorous acid, followed by reaction with an alkylating agent such as methyl chloride in a solvent to form a diesterquat. It is further disclosed that such diesterquats are useful as fabric softeners.
It was found that the process disclosed in U.S. Pat. No. 5,523,433 works well for the synthesis of dimethyl diesterquats and trimethyl monoesterquats, but not for dialkyl diesterquats such as dibutyl diesterquats and trialkyl monoesterquats such as tributyl monoesterquats, containing C
8
-C
30
fatty acyl groups which could only be obtained in relatively low yields. Another drawback is that a solvent is used.
EP-A-0 187 298 discloses a process wherein a trialkanol amine is esterified with an acid chloride and quaternized with a quaternizing agent. According to the description (page 4, lines 14-15), triethanol amine is the preferred tertiary amine. The length of the acyl group of the acid chloride is defined as from 2 to 10 carbon atoms in total, and Examples 1-3 and 4 describe the use of acetyl chloride and octanoyl chloride, respectively. It further discloses that the esterquats have surface-active properties and may be used as detergents. In Example 3 of this document it is described that solid n-butyl tris(2,3-di-hydroxypropyl)ammonium chloride, obtained by reacting bis(2,3-dihydroxypropyl)-n-butyl amine with 1-chloro-2,3-propanediol, was reacted with a 100% excess of acetyl chloride at reflux temperature for 5 hours to 95% completion. The reaction product was dried and subsequently crystallized from a mixture of organic solvents.
Just as U.S. Pat. No. 5,523,433, EP-A-0 187 298 does not relate to the preparation of esterquats in accordance with the present invention such as dibutyl diesterquats and tributyl monoesterquats containing C
8
-C
30
fatty acyl groups either.
In view of the prior art discussed above, it was concluded that there is need in the art for an improved, economic route for synthesizing esterquats on a commercial scale.
SUMMARY OF THE INVENTION
The present invention is a process for preparing an esterquat composition comprising (a) reacting a tertiary amine according to formula l:
wherein R
1
represents a C
3
-C
6
hydrocarbon group, R
2
represents a C
3
-C
6
hydrocarbon group, a —R
4
—OH group or a —CH
2
[CH(OH)]
n
CH
2
OR
5
group, if R
2
represents a C
3
-C
6
hydrocarbon group, R
3
represents a —R
4
—OH group or a —CH
2
[CH(OH)]
n
CH
2
OR
5
group, if R
2
represents a —R
4
—OH group, R
3
represents a —R
4
—OH group or a —CH
2
[CH(OH)]
n
CH
2
OR
5
group, if R
2
represents a —CH
2
[CH(OH)]
n
CH
2
OR
5
group, R
3
represents a —CH
2
[CH(OH)]
n
CH
2
OR
5
group, R
4
represents a C
2
-C
4
hydrocarbon group, n is 1-4, and R
5
represents H or a C
1
-C
30
hydrocarbon group, with a C
3
-C
6
hydrocarbyl halide or a di(C
3
-C
6
) hydrocarbyl sulfate, followed by (b) reaction with a C
8
-C
30
acid halide, with the proviso that at least one hydroxy group is esterified. Additionally, the invention includes compositions comprising this esterquat and the use of such compositions as a gas hydrate growth inhibitor.
DETAILED DESCRIPTION OF THE INVENTION
As described above, esterquats may be used for inhibiting the plugging of conduits by gas hydrates. Compositions comprising said esterquats need to be transported and pumped through pipelines into the production lines near the gas or oil well. This requires a composition having a high active content with regard to the esterquat, which reduces transportation and storage costs, a low viscosity, which eases pumping, and a solidification temperature lower than −10° C., which ensures handling of the esterquat composition in cold climate areas during winter time.
Surprisingly, a new and efficient process using readily available starting materials and standard production equipment and new esterquat compositions which meet the active content, viscosity, and solidification temperature requirements discussed above were found.
The process according to the present invention for preparing an esterquat composition comprises
(a) reacting a tertiary amine according to formula I:
wherein
R
1
represents a C
3
-C
6
hydrocarbon group,
R
2
represents a C
3
-C
6
hydrocarbon group, a —R
4
—OH group or a —CH
2
[CH(OH)]
n
CH
2
OR
5
group,
if R
2
represents a C
3
-C
6
hydrocarbon group, R
3
represents a —R
4
—OH group or a —CH
2
[CH(OH)]
n
CH
2
OR
5
group,
if R
2
represents a —R
4
—OH group, R
3
represents a —R
4
—OH group or a —CH
2
[CH(OH)]
n
CH
2
OR
5
group,
if R
2
represents a —CH
2
[CH(OH)]
n
CH
2
OR
5
group, R
3
represents a —CH
2
[CH(OH)]
n
CH
2
OR
5
group,
R
4
represents a C
2
-C
4
hydrocarbon group,
n is 1-4, and
R
5
represents H or a C
1
-C
30
hydrocarbon group, with a C
3
-C
6
hydrocarbyl halide or a di(C
3
-C
6
) hydrocarbyl sulfate, followed by
(b) reaction with a C
8
-C
30
acid halide, with the proviso that at least one hydroxy group is esterified.
R
1
may be a linear or branched C
3
-C
6
hydrocarbon group. If R
2
represents a C
3
-C
6
hydrocarbon group, it may be a line

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