Defoaming of ionic liquids

1. A method of defoaming a composition containing at least 80% by weight of one or more ionic liquids and, optionally, a solvent and/or further auxiliaries or additives, the composition being free of ketone residues, ketone-aldehyde resins, and/or urea-aldehyde resins and/or their hydrogenated derivatives, the method comprising:

adding a polyether siloxane antifoam to said composition.

2. The method according to claim 1 ;

wherein the antifoam contains finely divided, hydrophobic particles.

3. The method according to claim 1 ;

wherein the antifoam contains further additives and emulsifiers.

4. The method according to claim 1 ;

wherein the antifoam has been emulsified in water using a customary additive comprising at least one of an emulsifier, a thickener, a protective colloid, and a preservative.

5. The method according to claim 1 ;

wherein at least one of an organic solvent water, and a mixture thereof is used as a solvent.

6. The method according to claim 5 ;

wherein the solvent is an organic solvent.

7. The method according to claim 1 ,

wherein said polyether siloxane is a compound of the general formula (E-1), (E-2), (E-2a), (E-2b), or (E-3);

wherein formula (E-1) is defined as:

where:

R 1 in the average molecule can be identical or different and are each a radical —Z—(C n H 2n —O) m R′, where R′ is hydrogen or an alkyl radical having from 1 to 8 carbon atoms or acyl;

R 2 is phenyl, ethyl, methyl, hydroxyl, amine with at least 90% methyl;

Z is a divalent radical of the formula —O—, —NH—, —NR 3 — where R 3 ═C 1-4 -alkyl radical, —S—, —(CH 2 ) p —O— where p =2, 3, 4, or —CH 2 —CH(CH 3 )—CH 2 —O—;

n has an average numerical value of from >2.5 to 4.0;

m has an average numerical value of from 5 to 350;

a has an average numerical value of from 4 to 1500;

b has an average numerical value of from 0 to 100; and

c has an average numerical value of from 0 to 100;

wherein formula (E-2) is defined as:

where the radical A is a polyoxyalkylene block of the average formula (E-2a);

[(C 2 H 4-d R′ d O) n (C x H 2x O) r (C 2 H 4-d R″ d O) t ]  (E-2a)

where:

d is from 1 to 3;

n ≧0;

x is from 2 to 10;

r ≧0;

t ≧0;

n +r +t ≧1;

R′ is a monovalent aromatic, substituted or unsubstituted hydrocarbon radical;

R″ is hydrogen or a monovalent hydrocarbon radical having from 1 to 18 carbon atoms; and

R 1 is an H atom, a monovalent organic linear or branched alkyl radical having from 1 to 40 carbon atoms or a carboxy radical of a branched or unbranched alkyl or aryl ester;

where the radical B is a polysiloxane block of the average formula (E-2b),

where:

the radicals R 2 are identical or different and are each an alkyl radical having from 1 to 4 carbon atoms or a phenyl radical; and

y is from 5 to 200; and

where:

m is from 2 to 100;

p is 0 or 1; and

q is 0 or 1; and

wherein formula (E-3) is defined as:

where:

R 1 , A, B, m, p, and q are as defined above in the case of structure (E-2); and

C is a linear or branched alkylene radical having from 2 to 20 carbon atoms.

8. The method of claim 1 , further comprising:

after the polyether siloxane antifoam has been added to the composition to obtain a defoamed composition, performing an additional step of at least one of:

using the defoamed composition as at least one of:

a lubricant, a hydraulic fluid, a thermal fluid, an electrolyte liquid, an absorbent in an absorption refrigeration process, a cleaning liquid; and

using the defoamed composition in at least one of:

a separation process, a biorefinery process, a cellulose spinning process and a cellulose derivatization.

9. The method of claim 1 ;

wherein the composition comprises:

from 80 to 99.999% by weight of one or more ionic liquids;

from 0 to 20% by weight of solvents; and

from 0 to 20% by weight of auxiliaries and additives; and

wherein said polyether siloxane antifoam is added in an amount of from 0.001 to 10% by weight.

10. The method of claim 1 ;

wherein said one or more ionic liquids are compounds of formula (i):

R 6 4−m N + [((CH 2 ) n -Q-R 7 ] m X −   (i)

where:

each radical R 6 is independently an alkyl group, or hydroxyalkyl group having from 1 to 6 carbon atoms, or a benzyl group;

each radical R 7 is independently hydrogen, a linear or branched alkyl group having from 11 to 22 carbon atoms, or a linear or branched alkenyl group having from 11 to 22 carbon atoms, with the proviso that at least one radical R 7 is not hydrogen;

Q is selected independently from the one of the formulae —O—C(O)—, —C(O)O, —NR 8 —C(O)—, —C(O)—NR 8 —, —O—C (O)—O, —CHR 9 —O—C(O)— and —CH(OCOR 7 )—CH 2 —O—C(O)—;

where R 8 is hydrogen, methyl, ethyl, propyl or butyl; and

where R 9 is hydrogen or methyl; and

X − is chloride or methylsulphate.

11. The method of claim 10 ;

wherein said one or more ionic liquids of formula (i) are selected from the group consisting of:

N,N-di(tallowyloxyethyl)-N,N-dimethylammonium chloride;

N,N-di(canolyloxyethyl)-N,N-dimethylammonium chloride;

N,N-di(tallowyloxyethyl)-N-methyl-N-(2-hydroxyethyl) ammonium methylsulphate;

N,N-di(canolyloxyethyl)-N-methyl-N-(2-hydroxyethyl) ammonium methylsulphate;

N,N-di(tallowylamidoethyl)-N-methyl-N-(2-hydroxyethyl) ammonium methylsulphate;

N,N-di(2-tallowyloxy-2-oxo-ethyl)-N,N-dimethylammonium chloride;

N,N-di(2-canolyloxy-2-oxo-ethyl)-N,N-dimethylammonium chloride;

N,N-di(2-tallowyloxyethylcarbonyloxyethyl)-N,N-ditnethylarmmonium chloride;

N,N-di(2-canolyloxyethylcarbonyloxyethyl)-N,N-dimethylammonium chloride;

N-(2-tallowoyloxy-2-ethyl)-N-(2-tallowyloxy-2-oxo-ethyl)-N,N-dimethylammnonium chloride;

N-(2-canolyloxy-2-ethyl)-N-(2-canolyloxy-2-oxo-ethyl)-N,N-dimethylammnonium chloride;

N,N,N-tri(tallowyloxyethyl)-N-methylammonium chloride;

N,N,N-tri(canolyloxyethyl)-N-methylammonium chloride;

1,2-ditallowyloxy-3-N,N,N-trimethylammoniopropyl chloride; and

1,2-dicanolyloxy-3-N,N,N-trimethylammoniopropyl chloride.