Carboxy alkyl-ester anti-agglomerants for the control of natural gas hydrates
This disclosure relates to anti-agglomerant low dosage hydrate inhibitors that can inhibit the formation of hydrate agglomerants and/or plugs. Thus, provided herein are carboxy alkyl ester compounds that can be used in hydrate inhibitor compositions and methods of inhibiting formation of hydrate agglomerants in a fluid comprising water, a gas, and optionally a liquid hydrocarbon. Also provided herein are methods of making the carboxy alkyl ester compound.
1. A compound having the structure of formula (Ia) or an acid, a free base, a zwitterion, or a salt thereof:
wherein
R 1 is C 10 to C 24 alkyl or alkenyl or straight or branched C 6 -C 24 alkyl and contains 1 to 12 ethylene oxide units;
R 5 is hydrogen;
R 2 is hydrogen;
R 4 is hydrogen; and
R 6 and R 7 are independently alkyl or R 6 and R 7 together with the nitrogen they are attached to form a ring.
2. The compound of claim 1 , wherein R 6 and R 7 are the same.
3. A compound having the structure of formula (Ie) or an acid, a free base, a zwitterion, or a salt thereof:
wherein
R 1 is hydrogen;
(ii) R 5 is C 10 to C 24 alkyl or alkenyl or straight or branched C 6 -C 24 alkyl and contains 1 to 12 ethylene oxide units;
R 4 is hydrogen;
A is a nitrogen-containing heterocycle, wherein the nitrogen-containing heterocycle is an optionally substituted pyrrolidine, piperidine, pyrazolidine, imidazolidine, isoxazolidine, oxazolidine, or azepane.
4. The compound of claim 3 , wherein the nitrogen-containing heterocycle is pyrrolidine, piperidine, pyrazolidine, imidazolidine, isoxazolidine, oxazolidine, or azepane.
5. A compound selected from the group consisting of:
6. A hydrate inhibitor composition comprising a hydrate-inhibiting effective amount of a compound of formula (I) of claim 1 .
7. A method of inhibiting formation of hydrate agglomerants in a fluid comprising water, a gas, and optionally a liquid hydrocarbon, the method comprising contacting the fluid with an effective amount of a hydrate inhibitor composition of claim 6 .
8. The compound of claim 1 , wherein R 1 is C 10 to C 24 alkyl.
9. The compound of claim 1 , wherein R 1 is C 10 to C 24 alkenyl.
10. The compound of claim 1 , wherein R 1 is straight or branched C 6 -C 24 alkyl and contains 1 to 12 ethylene oxide units.
11. The compound of claim 1 , wherein R 6 and R 7 are independently alkyl.
12. The compound of claim 1 , wherein R 6 and R 7 are independently C 1 to C 6 alkyl.
13. The compound of claim 5 , comprising:
14. The compound of claim 3 , wherein A is pyrrolidine.
15. The compound of claim 14 , wherein R 5 is C 10 to C 24 alkyl or alkenyl.
16. The compound of claim 14 , wherein R 5 is straight or branched C 6 -C 24 alkyl and contains 1 to 12 ethylene oxide units.