PROCESS FOR STABILIZATION OF AT LEAST MONOALKYL-SUBSTITUTED DIAMINOCYCLOHEXANES

Abstract

A process for stabilizing monoalkyl-substituted diaminocyclohexanes, the process containing: adding a reductant and optionally water to a first composition containing a monoalkyl-substituted diaminocyclohexane and optionally water to obtain a second composition, wherein the second composition contains the reductant, the monoalkyl-substituted diaminocyclohexane and additionally at least 0.05% by weight of water based on the total weight of the second composition.

Claims

1. A process for stabilizing at least monoalkyl-substituted diaminocyclohexanes, the process comprising: adding at least one reductant and optionally water to a first composition comprising at least one at least monoalkyl-substituted diaminocyclohexane and optionally water to obtain a second composition, wherein the second composition comprises the at least one reductant, the at least one at least monoalkyl-substituted diaminocyclohexane and additionally at least 0.05% by weight of water based on a total weight of the second composition.

2. The process of claim 1, wherein the at least one at least monoalkyl-substituted diaminocyclohexane is a compound of formula (I), (II) or (III) ##STR00002## wherein R.sub.1, R.sub.1, R.sub.2, R.sub.2, R.sub.3, R.sub.3, R.sub.4 and R.sub.4 are independently of one another selected from the group consisting of H and C.sub.1-C.sub.4-alkyl, and at least one of radical R.sub.1, R.sub.1, R.sub.2, R.sub.2, R.sub.3, R.sub.3, R.sub.4 and R.sub.4 is C.sub.1-C.sub.4-alkyl.

3. The process of claim 1, wherein the at least one at least monoalkyl-substituted diaminocyclohexane is selected from the group consisting of 1,3-diamino-4-methylcyclohexane and 1,3-diamino-2-methylcyclohexane.

4. The process of claim 1, wherein the first composition comprises at least 85% by weight of the at least one at least monoalkyl-substituted diaminocyclohexane based on a total weight of the first composition.

5. The process of claim 1, wherein the at least one reductant is selected from the group consisting of lithium borohydride, sodium borohydride, potassium borohydride, sodium cyanoborohydride, lithium aluminum hydride, sodium aluminum hydride and potassium aluminum hydride.

6. The process of claim 1, wherein the second composition comprises 0.005 to 0.2% by weight of the at least one reductant based on the total weight of the second composition.

7. The process of claim 1, wherein the adding comprises adding the at least one reductant in the form of a solid, in a solution or in a suspension.

8. The process of claim 7, wherein a mixture comprises at least one basic compound selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, magnesium carbonate and calcium carbonate.

9. The process of claim 7, wherein the solution comprises: a) 5% to 20% by weight of the at least one reductant, b) 10% to 65% by weight of at least one basic compound and c) 15% to 85% by weight of water, wherein weight fractions of components a), b) and c) altogether sum to 100% by weight.

10. The process of claim 1, further comprising: initially performing a distillation of the first composition to remove higher boiling byproducts and to obtain a distilled composition comprising the at least one at least monoalkyl-substituted diaminocyclohexane and optionally water, and adding the at least one reductant and optionally water to the distilled composition to obtain the second composition, wherein the second composition comprises at least 0.05% by weight of water based on the total weight of the second composition.

11. The process of claim 10, wherein i) the distillation is effected at a temperature in a range from 70 C. to 180 C., and/or ii) the distillation is effected at a pressure in a range from 0.1 to 500 mbar.

12. The process of claim 1, wherein i) at least a portion of the water present in the second composition is already present in the first composition, wherein the first composition comprises a water content of 0.05% to 1% by weight based on a total weight of the first composition, and/or ii) the process further comprises adding water, and/or iii) at least a portion of the water present in the second composition is added together with the at least one reductant.

13. The process of claim 1, wherein the second composition comprises 0.05% to 3% by weight of water based on the total weight of the second composition.

14. The process of claim 1, wherein a weight ratio of water to the at least one reductant in the second composition is 100:1 to 1:1.

15. A second composition, comprising the second composition comprises the at least one reductant, the at least one at least monoalkyl-substituted diaminocyclohexane and additionally at least 0.05% by weight of water based on a total weight of the second composition.

16. An article, for comprising: the second composition of claim 15, wherein the article is selected from the group consisting of a surfactant, a pharmaceutical and plant protection product, a stabilizer, a light stabilizer, a polymer, an isocyanate, a hardener for epoxy resin, a catalyst for polyurethane, an intermediate for producing a quaternary ammonium compound, a plasticizer, a corrosion inhibitor, a synthetic resin, an ion exchanger, a textile auxiliary, a dye, a vulcanization accelerator and an emulsifier.

Description

EXAMPLE 1

[0118] Samples of an undistilled composition (ZE) comprising a mixture of 1,3-diamino-2-methylcyclohexane and 1,3-diamino-4-methylcyclohexane and 0.15% by weight of water are filled into 250 mL screwtop glass jars, admixed with sodium borohydride and optionally water to obtain a composition (ZP) and stored in a drying cabinet at 80 C. (see experiments 1 and 2 in table 1).

[0119] Also, 895 g of the composition (ZE) are distilled via a distillation bridge at 1 mbar and 104 C. (top temperature). 805 g of a distilled composition (DZE) comprising approximately 0.15% by weight of water are obtained. Samples of this distilled composition (DZE) are likewise filled into 250 mL screwtop glass jars, admixed with sodium borohydride and optionally water to obtain a composition (ZP) and stored in a drying cabinet at 80 C. (see experiments 3 to 9 in table 1).

[0120] For reference an undistilled sample (V1) not admixed with sodium borohydride and a distilled sample (V2) not admixed with sodium borohydride are stored and analyzed. All samples are regularly opened and aerated and per measurement about 6 g are withdrawn for the color number determination.

[0121] The corresponding experimental data are reported in table 1. Reported in the columns is the Hazen color number at the respective times recited in the uppermost row.

TABLE-US-00001 TABLE 1 NaBH.sub.4 Water [% by addition Experiment wt.] [% by wt.] 0 h 24 h 48 h 72 h 96 h 168 h 192 h 240 h V1 12 29 48 78 149 318 683 >1000 V2 0 0 5 15 31 89 204 509 1 0.05 12 48 77 103 106 220 282 385 2 0.05 +0.3 12 29 54 79 49 66 135 261 3 0.1 +0.5 0 58 92 122 128 96 72 67 4 0.1 +1.0 0 15 38 45 54 22 23 74 5 0.1 +1.5 0 10 17 12 44 25 68 178 6 0.05 +0.2 0 51 92 100 92 127 140 188 7 0.05 +0.5 0 56 69 75 85 56 59 167 8 0.05 +1.0 0 12 28 58 49 23 34 226 9 0.01 0 15 24 32 32 22 29 121

[0122] The experimental data quoted in table 1 show that the Hazen color number of the composition (ZP) can be kept markedly lower in the long term when the at least one reductant (R) and optionally water are employed (experiments 1 to 9). When the composition (ZE) was initially distilled and subsequently admixed with the at least one reductant (R) and optionally water (see experiments 3 to 9) the Hazen color number is lower over a longer period than for undistilled stabilized compositions (ZP) (see experiments 1 and 2).

EXAMPLE 2

[0123] Samples of an undistilled composition (ZE) comprising a mixture of 1,3-diamino-2-methylcyclohexane and 1,3-diamino-4-methylcyclohexane and 0.15% by weight of water are filled into 250 mL screwtop glass jars, admixed with sodium borohydride/Borol (12.5% by weight sodium borohydride in an aqueous, 14 molar solution of sodium hydroxide obtainable from Dow Chemicals) and optionally water to obtain a composition (ZP) and stored in a drying cabinet at 80 C. (see experiments 1 and 2 in table 2).

[0124] Also, 860 g of the composition (ZE) were distilled via a distillation bridge at 1 mbar and 104 C. (top temperature). 730 g of a distilled composition (DZE) comprising approximately 0.15% by weight of water are obtained. Samples of this distilled composition (DZE) are likewise filled into 250 mL screwtop glass jars, admixed with sodium borohydride/Borol and optionally water to obtain a composition (ZP) and stored in a drying cabinet at 80 C. (see experiments 3 to 7 in table 2).

[0125] For reference a distilled sample (experiment V3) not admixed with a reductant (R) is stored and analyzed. Since the undistilled composition (ZE) is identical to the undistilled composition (ZE) from example 1 the reference measurement of the undistilled sample not admixed with a reductant (R) corresponds to the experiment V1 from example 1. All samples are regularly opened and aerated and per measurement about 6 g are withdrawn for the color number determination.

[0126] In the experiments 1 to 5 Borol is employed as the reductant (R) and in the experiments 6 and 7 sodium borohydride is employed as the reductant (R). The reported weight fractions of the at least one reductant (R) in table 2 which follows always relate to the employed amount of sodium borohydride. When for example Borol is used as the reductant (R) then the designation 0.02% by weight is to be understood as meaning that a certain amount of Borol is employed until 0.02% by weight of sodium borohydride have been added by means of Borol.

[0127] The corresponding experimental data are reported in table 2. Reported in the columns is the Hazen color number at the respective times recited in the uppermost row.

TABLE-US-00002 TABLE 2 Water Reductant addition (R) [% by Experiment [% by wt.] wt.] 0 h 24 h 48 h 72 h 96 h 168 h 192 h 240 h V1 12 29 48 78 149 318 683 >1000 V3 0 1 3 12 30 102 251 538 1 0.02 0 71 116 155 208 368 487 653 2 0.04 0 105 97 97 130 412 360 501 3 0.01 0 8 14 15 12 24 33 152 4 0.02 0 10 17 22 16 20 35 218 5 0.04 0 32 63 72 83 67 83 185 6 0.02 +0.1 0 19 38 39 52 34 41 115 7 0.04 +0.2 0 39 89 94 100 75 70 177

[0128] The experimental data quoted in table 2 show that the Hazen color number of the composition (ZP) can be kept markedly lower in the long term when the at least one reductant (R) and optionally water are employed (experiments 1 to 7). When the composition (ZE) is initially distilled and subsequently admixed with the at least one reductant (R) and optionally water (see experiments 3 to 7) the Hazen color number is lower over a longer period than for undistilled stabilized compositions (ZP) (see experiments 1 and 2).

EXAMPLE 3

[0129] 449 g of an undistilled composition (ZE) comprising 99.76% by weight of a mixture of 1,3-diamino-2-methylcyclohexane and 1,3-diamino-4-methylcyclohexane and 0.24% by weight of further compounds are distilled at 70 mbar and 136 C. (top temperature). 51 g of a first fraction are obtained and separated and subsequently 343 g of a distilled composition (DZE) are obtained. This distilled composition (DZE) comprises no water.

[0130] Samples of this distilled composition (DZE) are filled into 250 mL screwtop glass jars, admixed with a reductant (R) and stored in a drying cabinet at 80 C.

[0131] For reference a distilled sample (experiment V1) not admixed with a reductant (R) is stored and analyzed. All samples are regularly opened and aerated and per measurement about 6 g are withdrawn for the color number determination.

[0132] In experiment V2 Borol (12.5% by weight sodium borohydride in an aqueous, 14 molar solution of sodium hydroxide obtainable from Dow Chemicals) is employed as the reductant (R) and in experiment V3 sodium borohydride is employed as the reductant (R). The reported weight fractions of the at least one reductant (R) in table 3 which follows always relate to the employed amount of sodium borohydride. When Borol is used as the reductant (R) then the designation 0.1% by weight for example is to be understood as meaning that a certain amount of Borol is employed until 0.1% by weight of sodium borohydride have been added by means of Borol. When using Borol the water content of the samples is always below 0.1% by weight.

[0133] The corresponding experimental data are reported in table 3. Reported in the columns is the Hazen color number at the respective times recited in the uppermost row.

TABLE-US-00003 TABLE 3 Ex- Reductant peri- (R) ment [% by wt.] 0 h 24 h 48 h 72 h 96 h 168 h 192 h 240 h V1 0 0 3 11 32 78 159 305 V2 0.1 0 3 9 45 104 253 402 791 V3 0.1 1 96 123 195 260 339 837 >1000

[0134] The experimental data quoted in table 3 show that for a low Hazen color number in the long term not only the at least one reductant (R) but also at least 0.05% by weight of water based on the total weight of the composition (ZP) must be present in the composition (ZP).

EXAMPLE 4

[0135] Samples of an undistilled composition (ZE) comprising a mixture of 1,3-diamino-2-methylcyclohexane and 1,3-diamino-4-methylcyclohexane and 0.15% by weight of water are filled into 250 mL screwtop glass jars, admixed with sodium borohydride or a sodium borohydride stock solution to obtain a composition (ZP) and stored in a drying cabinet at 60 C. (see experiments 1 and 2 in table 4).

[0136] For reference an undistilled sample (V1) not admixed with sodium borohydride is stored and analyzed. All samples are regularly opened and aerated and per measurement about 6 g are withdrawn for the color number determination.

[0137] The sodium borohydride stock solution is produced as follows: In a 100 mL stirred flask fitted with a bubble counter and under nitrogen 2 g of NaBH.sub.4 powder are initially charged and subsequently 18 g of the composition (ZE) are added thereto. After one hour of stirring the NaBH.sub.4 is except for a few crystals almost fully dissolved. The supernatant solution is used as NaBH.sub.4 stock solution.

[0138] The corresponding experimental data are reported in table 4. Reported in the columns is the Hazen color number at the respective times recited in the uppermost row.

TABLE-US-00004 TABLE 4 Addition NaBH.sub.4 Stock [% by solution Experiment wt.] [% by wt.] 0 h 24 h 48 h 72 h 144 h 168 h 192 h 312 h 336 h 360 h 384 h 408 h V1 21 27 36 47 89 106 128 233 277 326 386 454 1 0.01 21 41 36 35 48 57 67 107 122 141 171 183 2 0.01 21 38 32 32 51 60 70 111 129 147 172 198

[0139] The experimental data quoted in table 4 show that the Hazen color number of the composition (ZP) can be kept markedly lower in the long term when sodium borohydride or a sodium borohydride stock solution are employed (experiments 1 and 2).