GB2024243A

GB2024243A - Stabilization of 1,1,1- trichloroethane

Info

Publication number: GB2024243A
Application number: GB7922751A
Authority: GB
Original assignee: Rhone Poulenc Industries SA
Current assignee: Rhone Poulenc Industries SA
Priority date: 1978-06-30
Filing date: 1979-06-29
Publication date: 1980-01-09
Also published as: ES8102079A1; DE2926000B2; IT7949564A0; CA1133949A; NL7905097A; DK275979A; DE2926000C3; GB2024243B; CH640492A5; FR2437392A1; SE445826B; BE877385A; JPS595563B2; ATA457479A; GR69971B; DE2926000A1; AT370712B; JPS5511583A; NL187851C; FR2437392B1

Abstract

1,1,1-Trichloroethane is stabilized with respect to metals in the presence of light and/or oxygen-bearing gas by (a) 0.1 to 5% by weight of tertiary butyl alcohol; (b) 0.1 to 5% by weight of 2- methylbut-3-yn-2-ol and/or trioxan, (c) from 0.1 to 5% by weight of at least one C3-8 epoxide or chlorinated epoxide; (d) from 0.1 to 3% by weight of at least one C1-3 nitroalkane; and (e) from 0.001 to 1% by weight of a C4-10 aliphatic or cyclic amine. The resulting composition can be used for degreasing and/or cleaning metal articles, or for dry-cleaning textiles.

Description

SPECIFICATION Stabilisation of 1,1,1 -trichloroethane The present invention concerns the stabilisation of 1,1,1 -trichloroethane.

In the description of the invention, percentages given are expressed by weight, unless indicated to the contrary.

It is well known that 1,1,1-trichloroethane is unstable when it is brought into contact with metals such as aluminium and its alloys and magnesium and its alloys. The instability of 1,1,1 -trichloroethane is revealed by decomposition with accompanying formation of hydrochloric acid and other decomposition products, and colouring of the 1,1,1 -trichloroethane. This is a serious disadvantage from the point of view of its use as a solvent for degreasing and/or cleaning metal members or parts.

A very large number of compounds have been put forward as agents for inhibiting decomposition, or for stabilising 1,1,1-trichloroethane. Thus, US Patent No 2,371,644 proposes primary, secondary or tertiary alcohols such as tertiary amyl alcohol are described as being less efficient than primary and secondary alcohols, while US Patent No 3,000,978 refers to tertiary buty alcohol as being more efficient than tertiary amyl alcohol and also more efficient than secondary butyl alcohol, isopropanol, n-propanol or ethanol.

Moreover, US Patent No 2,371,645 describes cyclic esters such as propylene oxide and isobutylene oxide and CanadianPatent No 627,411 proposes incorporating nitromethane in 1,1,1 -trichloroethane.

However, these constituents, taken separately, provide only a very unsatisfactory degree of stability, in particular for prolonged uses of 1,1,1-trichloroethane in degreasing and/or cleaning metal or other articles.

In order to improve the degree of stability of the chlorinated solvent, British Patent No 912,118 discloses the addition to 1,1,1-trichloroethane, of a nitroalkane and an epoxide simultaneously, or a nitroalkane and a monohydroxyl aliphatic alcohol containing up to 5 carbon atoms. However, as the 1,1,1 -trichlornethane is itself made particularly sensitive to decomposition at the temperatures at which it is used as a degreasing and/or cleaning agent, because of the presence of greases, metal surfaces and metal impurities in suspension in the cleaning bath, such combinations of stabilizing agents are unable to provide 1,1,1 -trichlornethane with an effective degree of stability.

Even the ternary combination of nitromethane, tertiary butyl alcohol and 1,2-butylene oxide mentioned in US Patent No 3,281,480 cannot prevent the formation of an ambercoloured precipitate in the solvent, after contact with aluminium for 24 hours. The same also applies in regard to monohydroxyl aliphatic acetylenic alcohols containing less than 8 carbon atoms, more particularly 2-methylbut-3-yn-2-ol, which are associated with 1,4-dioxan, in accordance with US Patent No 2,838,458.

According to the invention, stabilization of 1,1,1 -trichloroethane is achieved by incorporating in it: (a) from 0.1 to 5% and preferably from 0.5 to 3.5% by weight of tertiary butyl alcohol; (b) from 0.1 to 5% and preferably from 0.3 to 3% by weight of at least one of 2-methylbut-3-yn-2-ol and trioxan; (c) from 0.1 to 5% by weight of at least one C38 epoxide or chlorinated epoxide; (d) from 0.1 to 3% by weight of at least one Cl 3 nitroalkane; and (e) from 0.001 to 1% and preferably from 0.005 to 0.1% by weight of at least one aliphatic, cyclic or heterocyclic C410 amine of a basic nature.

The amines used according to the invention include C410 aliphatic amines, preferably secondary or tertiary, with a straight or branched carbon-bearing chain; C6 aromatic amines substituted by halogen atoms or C1 to C3 alkyl groups; and heterocyclic amines having 1 or 2 nitrogen atoms in the molecule, e.g.

diethylamine, triethylamine, diisopropylamine, di-sec-butylamine, amylamines, hexylamines, pyridines, picolines, morpholinem N-(C1.3 alkyl)morpholines, pyrrolidine, and N-(C1.3 alkyl)pyrrolidines.

Particularly advantageous amines for use in accordance with the invention are N-methyl-morpholine, di-isopropylamine and pyrrolidine.

In the following description, in order not to encumber the text, the percentages given are expressed by weight, unless indicated to the contrary.

When the mixture of tertiary butyl alcohol and 2-methylbut-3-yn-2-ol is associated with 1,1,1-.

trichloroethane, this binary mixture comprises from 1 to 99% of tertiary butyl alcohol and from 99 to 1% of 2-methylbut-3-yn-2-ol and preferably from 25 to 80% of tertiary butyl alcohol for from 75 to 20% of 2-methylbut-3-yn-2-ol.

In accordance with an advantageous embodiment of the invention, trioxan is incorporated in the 1,1,1 -trichloroethane, in proportions of from 0.5 to 3%, without 2-methylbut-3-yn-2-ol.

Representative compounds of the C3to C8 epoxide and chlorinated epoxide include in particular 1,2-butylene oxide, which is preferred, epichlorohydrin, glycidol and its primary, secondary and tertiary methyl, ethyl, propyl, isopropyl, allyl and butyl ethers, 1,2-propylene oxide, styrene oxideand cyclohexene oxide. The preferred proportion of expoxide is from 0.2 to 3% with respect to the 1,1,1 -trichloroethane.

The nitroalkanes are represented by nitromethane, nitroethane and the two isomers of nitropropane. The preferred proportion is from 1 to 2% with respect to the 1,1,1-trichloroethane.

It has in fact been found that the association of the above-mentioned compounds can be particularly advantageous because, in a comparable concentration, it has a stabilizing action substantially better than that achieved by the addition of each of the constituents taken in isolation.

The association of the above-indicated compounds may further be reinforced by the addition, as an anti-oxident, of at least one phenol and/or nitrogenous heterocycle having from 3 to 5 carbon atoms and from 1 to 2 nitrogen atoms with optionally an oxygen atom in the ring, in amounts of up to 1% and preferably from 0.001 to 0.1 % with respect to the 1,1,1 4richloroethane.

Among examples of suitable phenols are monohydric phenols such as phenol, cresols, ethylphenols, butylphenols, in particularp-ter-butylphenol, thymol, naphthols, methylnaphthols and eugenol; C1 or C2 alkyl ethers of monophenols such as anisol, guaiacol and 2-ethoxy phenol; diphenols such as resorcinol, pyrocatechol, naphthoquinone and in particular hydroquinone; C1 or C2walkyl ethers of said diphenols such as the monomethyl ether of hydroquinone; and triphenols such as pyrogallol, phloroglucinol, hydroxyhydroquinone and trihydroxytoluenes.

Examples of heterocycles with one nitrogen atom include pyrrole, N(C1.4)pyrroles, preferably Nmethylpyrrole, indole, 1 -methylindole, 2-butylindole, 2-phenylindole, 2-toluylindole, 1 -benzylindole and their respective isomers; oxazole and isoxazole are representative of heterocycles with one nitrogen atom and an oxygen atom.

Examples of nitrogen heterocycles with 2 nitrogen atoms include imidazole, pyrazole, pyrazoline, pyrazolidine, imidazoline, imidazolidine, piperazine and their N-(C1.4alkyl)ated derivatives, pyrazine, pyrimidine and pyridazine.

The invention also provides a composition which comprises 1,1,1-trichloroethane containing: (a) from 0.1 to 5% and preferably from 0.5 to 3.5% by weight of tertiary butyl alcohol; (b) from 0.1 to 5% and preferably 0.3 to 3% by weight of at least one of 2-methylbut-3-yn-2-ol and trioxan; (c) from 0.1 to 5% by weight of at least C3-8 epoxide or chlorinated epoxide; (d) from 0.1 to 3% by weight of at least one C1.3 nitroalkane.

(e) from 0.001% to 1% and preferably from 0.005% to 0.1% by weight of at least one aliphatic, cyclic or heterocyclic C4.10 amine of a basic nature; and (f) as anti-oxidant, from 1 to 1% and preferably less than 0.2% of at least one phenol and/or nitrogen heterocycle having from 3 to 5 carbon atoms, 1 or 2 nitrogen atoms and possibly an oxygen atom in the ring, as defined above; the said proportions being expressed with respect to the 1,1,1 -trichloroethane in the composition.

The preferred compositions of the invention essentially comprise 1,1,1 -trichloroethane containing: (a) from 1 to 3% of tertiary butyl alcohol; (b) from 0.5 to 2.5% of 2-methylbut-3-yn-2-ol and up to 2.5% of trioxan; (c) from 0.2 to 3% of 1 ,2-butylene oxide; (d) from 0.5 to 1.5% of nitromethane and/or nitroethane; and (e) from 0.005 to 0.1% of N-methyl-morpholine and/or diisopropylamine.

The following Examples are given to illustrate but not limit the invention and to set forth its specific advantages.

Example 1 The following compounds were incorporated in 1,1,1-trichloroethane: tertiary butyl alcohol 2.0 2-methylbut-3-yn-2-ol 1.5 1,2-butylene oxide 0.45 nitromethane 1.3 N-methylmorpholine 0.008 The resulting composition was tested by successive distillation. This comprises distilling itfourtimes in succession and in each distillation step collecting only the first 90% by volume that passes. The test in respect of scratching of aluminium plates in accordance with standard ASTM D 2943-71 Twas carried out on each ofthefourdistillates.

The scratching test is to determine the aptitude of the association of stabilizing agents in 1,1,1 trichloroethane, to prevent degradation of the chlorinated solvent in the presence of aluminium or aluminium alloys. It comprises taking a piece of metal that has been cleaned and degreased, of quality AA 1100 (Standard ASTM corresponding to AFNOR A 45 symbol aluminium), immersing it in 50 cc of stabilized 1,1,1 -trichloroethane at ambient temperature, and scratching it by means of a mild steel rod. After a period of time (1 hour) sufficient to allow any reaction to occur, the presence or absence of bubbles, colouring of the solvent or the presence of dark-coloured resinous products is noted. The 1,1,1 -trichloroethane is suitably stabilized if no reaction is observed.

The above composition passes this test, without any trace of reaction on the aluminium plates being observed.

A very severe long-term stabilization test was also carried out, viz. the test of the BAM (German Federal Institute for Testing of Materials). This test comprises carrying out three operations on a mixture of 100 cc of stabilized 1,1,1-trichloroethane and 100 cc of toluene: operation 1: addition of 18 g of aluminium in the form of thin sheets or plates, and 0.7 g of aluminium chloride operation 2: as operation 1, also adding 1 g of zinc stearate operation 3: as operation 1, also adding 10 ml of oleic acid.

For each operation, the mixtures were refluxed, the bath temperature being 11 4'C, for a period of 18 hours.

The stabilized 1,1,1 -trichloroethane was then distilled into three equal portions, in accordance with standard DIN 51 751, and then operation 1 was carried out on 100 cc of toluene.

The solvent was admitted as satisfying the test if there was no violent exothermic reaction recorded in the course of each of the six operations considered separately.

The composition set out hereinbefore passed the test, without any violent exothermic reaction being observed.

Example 2 1,1,1-Trichloroethane containing: tertiary butyl alcohol 2.0 2-methylbut-3-yn-2-ol 1.85 1 ,2-butylene oxide 0.45 nitroethane 1.3 pyrrolidine 0.01 successfully passed the successive distillation tests and the BAM tests described in Example 1.

Example 3 1,1,1-Trichloroethane to which the following were added: tertiary butyl alcohol 1.7 2-methylbut-3-yn-2-ol 2.0 1,2-butylene oxide 0.45 nitroethane 0.6 nitromethane 0.5 N-methylmorpholine 0.005 also successfully passed the successive distillation and BAM tests described in Example 1.

Example 4 1,1,1-Trichloroethane to which the following were added: tertiary butyl alcohol 2.0 2-methylbut-3-yn-2-ol 1.5 1,2-butylene oxide 0.45 nitromethane 1.3 N-methylpyrrole 0.008 N-methyl-morpholine 0.01 also successfully passed the successive distillation and BAM tests described in Example 1.

Example 5 In order to demonstrate the attraction of adding an associated amine to the other stabilizing agents of the invention, the following test was carried out: 98 ml of stabilized 1,1,1 -trichloroethane, mixed with 2 ml of a mixture of white spirit and water (in a proportion of 90% by volume of white spirit for 10% by volume of water) was boiled under reflux for 72 hours. The pH of the solvent was measured before and after the test.

With stabilized 1,1,1 -trichloroethane in accordance with the formula set out in Example 4, but without N-methyl-morpholine, the pH changed from 6.7 before the test to 4.5 after 72 hours of reflux (for this pH, it is known that the solvent is particularly corrosive for degreasing machines).

With 1,1,1 -trichloroethane stabilized in accordance with the formula set out in Example 4 (containing 0.01% of N-methyl-morpholine), the pH remained at 8.3 after 72 hours of reflux (at this pH there is virtually no corrosion of degreasing machines).

Example 6 1,1,1-Trichloroethane containing the following substances: tertiary butyl alcohol 2.4 2-methylbut-3-yn-2-ol 2.1 methylglycidic ether 0.5 nitromethane 1.3 diisopropylamine 0.005 successfully passed the successive distillation and BAM tests described in Example 1.

Example 7 The following composition also successfully passed the successive distillation and BAM tests described in Example 1: 1,1,1-trichloroethane 94.995 tertiary butyl alcohol 2.5 trioxan 1.4 1,2-butylene oxide 0.4 nitromethane 0.7 N-methyl-morpholine 0.005

Claims

1. A process for the stabilization of 1,1 1-trichloroethane, comprising incorporating in it: (a) from 0.1 to 5% by weight of tertiary butyl alcohol; (b) from 0.1 to 5% by weight of at least one of 2-methylbut-3-yn-2-ol and trioxan; (c) from 0.1 to 5% by weight of at least one C38 epoxide or chlorinated epoxide; (d) from 0.1 to 3% by weight of at least one C13 nitroalkane; and (e) from 0.001 to 1% by weight of at least one aliphatic, cyclic or heterocyclic C4 10 amine of a basic nature.

2. A process for the stabilization of 1,1,1-trichloroethane, comprising incorporating in it: (a) from 0.5 to 3.5% by weight of tertiary butyl alcohol; (b) from 0.3 to 3% by weight of at least one of 2-methylbut-3-yn-2-ol and trioxan; (c) from 0.2 to 3% by weight of at least one C38 epoxide or chlorinated epoxide; (d) from 0.1 to 3% by weight of at least one Con 3 nitroalkane; and (e) from 0.005 to 0.1% by weight of at least one aliphatic, cyclic or heterocyclic C4 10 amine of a basic nature.

3. A process according to claim 1 or 2 in which, when tertiary butyl alcohol and 2-methylbut-3-yn-2-ol are associated, the binary mixture comprises from 1 to 99% by weight of tertiary butyl alcohol and from 99 to 1% by weight of 2-methylbut-3-yn-2-ol.

4. A process according to claim 3 in which the binary mixture comprises from 25 to 80% by weight of tertiary butyl alcohol and from 75 to 20% by weight of 2-methylbut-3-yn-2-ol.

5. A process according to any one of claims 1 to 4 in which the epoxide is 1,2-butylene oxide.

6. A process according to any one of claims 1 to 4 in which the epoxide is epichlorohydrin, glycidol or its primary, secondary or tertiary methyl, ethyl, propyl, isopropyl, alyl or butyl ether, 1,2-propylene oxide, styrene oxide or cyclohexene oxide.

7. A process according to any one of claims 1 to 6 in which the compound selected in (b) is trioxan alone, in amounts of from 0.5 to 3% by weight.

8. A process according to any one of claims 1 to 7 in which the amine is diisopropylamine, N-methyl-morpholine or pyrrolidine.

9. A process according to any one of claims 1 to 8 in which the stabilization action is strengthened by the addition of, as an anti-oxidant, at least one phenol or nitrogeneous heterocycle having from 1 to 2 nitrogen atoms and from 3 to 5 carbon atoms with possibly an oxygen atom in the ring in an amount of up to 1% by weight with respect to the 1,1,1 -trichloroethane.

10. A process according to claim 10 in which the antioxidant is N-methylpyrrole.

11. A process according to claim 9 ar 10 in which the amount of antioxidant is from 0.001 to 0.1% by weight with respect to the 1,1,1 -trichloroethane.

12. A stabilized composition based on 1,1,1-trichloroethane, containing, as essential stabilizing agents: (a) from 0.1 to 5% by weight of tertiary butyl alcohol; (b) from 0.1 to 5% by weight of at least one of 2-methylbut-3-yn-2-ol and trioxan; (c) from 0.1 to 5% by weight of at least one C38 epoxide or chlorinated epoxide; (d) from 0.1 to 3% by weight of at least one C1.3 nitroalkane; (e) from 0.001 to 1% by weight of at least one aliphatic, cyclic or heterocyclic C4 10 amine of a basic nature; and (f) as antioxidant, from 0 to 1% by weight of at least one phenol and/or nitrogenous heterocycle having from 3 to 5 carbon atoms, from 1 to 2 nitrogen atoms and possibly an oxygen atom in the ring.

13. A composition according to claim 12 containing, as stabilizing agents; (a) from 0.5 to 3.5% by weight of tertiary butyl alcohol; (b) from 0.3 to 3% by weight of at least one of 2-methylbut-3-yn-2-ol and trioxan; (c) from 0.2 to 3% by weight of at least one C3-8 epoxide or chlorinated epoxide; (d) from 0.1 to 3% by weight of at least one C13 nitroalkane containing from 1 to 3 carbon atoms; (e) from 0.005 to 0.1% by weight of at least one C4 10 aliphatic, cyclic or heterocyclic amine of basic nature; and (f) an antioxidant, from 0.001 to 1.0% by weight of at least one phenol and/or nitrogenous heterocycle having from 3 to 5 carbon atoms, from 1 to 2 nitrogen atoms and possibly an oxygen atom in the ring.

14. A composition according to claim 12 or 13 containing a binary mixture of tertiary butyl alcohol and 2-methylbut-3-yn-2-ol comprising from 25 to 80% by weight of tertiary butyl alcohol for from 75 to 20% by weight of 2-methylbut-3-yn-2-ol.

15. A composition according to claim 12, 13 or 14 in which the epoxide is 1,2-butylene oxide.

16. A composition according to claim 12, 13 or 14 in which the epoxide is epichlorohydrin, glycidol or its primary, secondary or tertiary methyl, ethyl, propyl, isopropyl, allyl or butyl ether, 1,2-propylene oxide, styrene oxide or cyclohexene oxide.

17. A composition according to any one of claims 12 to 16 in which the amount of trioxan is from 0.5 to 3% and it is free from 2-methylbut-3-yn-2-ol.

18. A composition according to any one of claims 12 to 17 in which the amine is diisopropylamine, N-methyl-morpholine or pyrrolidine.

19. A composition according to any one of claims 12 to 18 in which the anti-oxidizing agent is N-methylpyrrole.

20. A composition according to claim 12, substantially as hereinbefore described in any one of the Examples.