GB2024242A

GB2024242A - Stabilization of 1,1,1- trichloroethane

Info

Publication number: GB2024242A
Application number: GB7922750A
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: BE877384A; IT7949563A0; DE2925968A1; GR67230B; GB2024242B; DE2925968C3; AT374444B; FR2429767A1; IT1119784B; CH640813A5; DE2925968B2; ES482051A1; FR2429767B1; ATA457579A

Abstract

1,1,1-Trichloroethane is stabilized with respect to metals in the presence of light and/or gas containing oxygen by incorporating into it 0.1 to 0.6% of tertiary butyl alcohol and tertiary amyl alcohol and possibly 2-methylbut-3-yn- 2-ol; from 0.1 to 5% of at least one epoxide, which is possibly chlorinated and which contains from 3 to 8 carbon atoms; and from 0.1 to 3% by weight of at least one nitroalkane containing from 1 to 3 carbon atoms, the percentages being by weight based on the weight of trichloroethane, with the condition that, on distillation of the stabilized 1,1,1- trichloroethane, the sum of the stabilizing agents concentrated in the head fractions represents from 40 to 60% by weight of the sum of the stabilizing agents concentrated in both the head fractions and the bottom fractions. The resulting compositions 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 -trichlornethane 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 monohydroxyl aliphatic alcohols. The 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 butyl 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 ethers such as propylene oxide and isobutylene oxide and Canadian Patent No 627,411 proposes incorporating nitromethane in 1,1,1-trichioroethane.

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 -trichloroethane 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 stabilising agents are unable to provide 1,1,1 -trichloroethane 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 amber-coloured 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, stabilisation of 1,1,1-trichloroethane is achieved by incorporating in it: from 0.1 to 6% of a mixture of tertiary amyl and butyl alcohols; from 0 to 3% of 2-methyl but-3-yn-2-ol; from 0.1 to 5% of at least one C3.8 epoxide or chlorinated epoxide, and from 0.1 to 3% of at least one C13 nitroalkane, with the condition that, on distillation of the stabilized 1,1,1 -trichloroethane, the weight of the stabilizing agents, concentrated in the head fractions represents from 40 to 60% of the weight of the stabilizing agents concentrated in both the head fractions and the bottom fractions.

Preferably the total amount of the alcohols is from 3 to 5%.

The stabilizing agents concentrated in the head fractions include in particular tertiary butyl alcohol and nitromethane. The stabilizing agents concentrated in the bottom fractions include in particular tertiary amyl alcohol, nitroethane, nitropropanes and 2-methylbut-3-yn-2-ol. Certain other stabilizing agents, for example 1 ,2-butylene oxide, virtually co-distil with the 1,1,1 -trichloroethane and accordingly are not concentrated either in the head fractions or in the bottom fractions.

When the mixture of tertiary butyl and tertiary amyl alcohols 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 tertiary amyl alcohol and preferably from 25 to 80% of tertiary butyl alcohol and 75 to 20% of tertiary amyl alcohol.

When using the mixture of the three tertiary alcohols, the relative proportions of each of the constituents of the ternary mixture are in most cases from 15 to 85% of tertiary butyl alcohol, from 1 to 50% of tertiary amyl alcohol and from 1 to 50% of 2-methylbut-3-yn-2-ol and preferably from 30 to 65%, from 15 to 35% and from 15 to 35% of the three respective constituents.

Representative of the optionally chlorinated C3 to C8 epoxides are in particular epichlorohydrin, glycidol and its primary, secondary or tertiary methyl, ethyl, propyl, isopropyl, allyl and butyl ethers, 1,2-propylene oxide, styrene oxide, cyclohexane oxide and preferably 1,2-butylene oxide. The preferred proportions of expoxide in the composition are from 0.2 to 3% with respect to the 1,1,1 -trichloroethane.

The nitroalkanes, at least one and preferably a mixture of at least two of which are incorporated in the composition, are represented by nitromethane, nitroethane and the two isomers of nitropropane. The preferred proportions are from 1 to 2% with respect to the 1,1,1 -trichloroethane.

The association of the above-indicated compounds has shown itself to be particularly advantageous because, in a comparable state of concentration, it has a stabilizing action markedly higher than the combined stabilizing action of each of the constituents taken separately.

It may be advantageous for certain other stabilizing agents to be incorporated in the 1,1,1 -trichloroethane, more particularly trioxan and/ortrimethyl orthoformateforexample, in a proportion of from 0.1 to 3.5% by weight with respect to the 1,1,1 -trichlornethane. When the stabilized 1,1,1 -trichloroethane is distilled, the trioxan is concentrated in the bottom fractions.

The association of the above-indicated compounds may further be reinforced by the addition, as an anti-oxidant, 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 respecttothe 1,1,1-trichloroethane.

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 C2 alkyl ethers of said diphenols such as the monomethyl ether or hydroquinone; and triphenols such as pyrogallol, phloroglucinol, hydroxyhyd roquinoneand trihydroxytoluenes.

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

Examples of suitable heterocycles with two nitrogen atoms include imidazole, pyrazole, pyrazoline, pyrazolidine, imidazoline, imidazolidine, piperazine or their N-alkylated derivatives, the alkyl group containing from 1 to 4 carbon atoms, pyrazine, pyrimidine and pyridazine.

The compositions that have optimum effectiveness in regard to certain degreasing uses also include a base. The term 'base' includes bases themselves, for example amines, and what may be called precursors of bases. The bases must be soluble in the 1,1,1-trichloroethane and preferably have a boiling temperature close to that of 1,1,1 -trichloroethane. It is evident however that some such bases form azeotropes with 1,1,1-trichloroethane and/or other components of the stabilizing system, which makes it impossible to remove them by distillation.Amines that can be used in accordance with the invention include C4 to C10 aliphatic amines, in particular those that are secondary or tertiary, such as triethylamine, diisopropylamine, diethylamine, di-sec-butylamine, amylamines and hexylamines; aniline substituted with halogen atoms and/or C13 alkyl residues; this may involve N or N,N-dialkylamine, the alkyl residue being a branched or straight-chain C14 residue; nitrogeneous heterocycles containing from 4 to 10 carbon atoms and from 1 to 2 nitrogen atoms in the molecule such as pyridines, picolines, morpholine and its N-(C1-3 alkyl)ated derivatives and pyrrolidine and its N-(C, 3 alkyl)ated derivatives, and which may also have other heteroatoms such as oxygen.

The amines that are particularly advantageous for use in accordance with the invention are Nmethylmorpholine, diisopropylamine and pyrrolidine.

The invention also provides a composition comprising 1,1,1-trichloroethane containing 0.1 to 6% of a mixture of tertiary amyl and butyl alcohols, 0 to 3% of 2-methylbut-3-yn-2-ol, preferably from 3 to 5% of the said alcohols altogether; from 0.1 to 5% of at least one C3.s epoxide or chlorinated epoxide; from 0.1 to 3% of at least one C13 nitroalkane, from 0 to 1% of at least one phenol and/or nitrogen heterocyclic containing from 3 to 5 carbon atoms and from 1 to 2 nitrogen atoms in the ring, as defined hereinbefore; and from 0 to 1% of at least one aliphatic amine and/or nitrogen heterocycle having from 4to 10 carbon atoms and from 1 to 2 nitrogen atoms in the molecule, such as those defined herein before, the said percentages all being expressed with respect to the 1,1,1 -trichloroethane in the composition, with the condition that, on distillation of the stabilized 1,1,1-trichloroethane, the sum of the stabilizing agents concentrated in the head fractions represents from 40 to 60% by weight of the shum of the stabilizing agents concentrated in both the head fractions and the bottom fractions.

The preferred compositions of the invention comprise, together with 1,1,1 -trichioroethane, 1 to 3% of tertiary butyl alcohol, from 0.5 to 2% of tertiary amyl alcohol, from 0 to 2% of 2-methylbut-3-yn-2-ol, from 0.2 to 3% of 1,2-butylene oxide, from 0.5 to 1.5% of nitromethane and from 0 to 1.5% of nitroethane.

In order to demonstrate the synergistic effect due to the association of the tertiary alcohols, in accordance with the invention, a test in respect of scratching of aluminium plates was carried out, in accordance with the standard ASTM D 2943-71 T, using 1,1,1 -trichloroethane to which different stabilizing agents had been added.

The objective of this scratching test is to determine the capability of the association of stabilizing agents in 1,1,1 -trichloroethane, to avoid degradation of the chlorinated solvent in the presence of aluminium or aluminium alloys. The test comprises taking a piece of cleaned and degreased metal of AA 1100 quality (ASTM standard corresponding to AFNOR symbol A 45 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) which is sufficient to allow any reaction to occur, the presence or the absence of bubbles, colouring of the solvent or the presence of dark resinous products is noted. The 1,1,1 -trichloroethane is suitably stabilized if no reaction is observed.

The following Table sets out the results of the scratching test carried out in respect of 1,1,1 -trichloroethane containing 1% of nitromethane, 0.45% of 1 ,2-butylene oxide, and the quantities of tertiary alcohols as set forth in the following Table: Results of the Test Tests Alcohols incorporated in the 1,1,1- Results ofthe Test No. trichloroethane (%) A B C Reaction No Reaction 1 2.3 X 2 2.7 X 3 2.5 X 4 3 X 5 2.5 X 6 3 X 7 0.75 0.85 X 8 0.45 0.5 0.6 X 9 0.4 0.85 0.35 X A, B and C: meaning as set out below: A = tertiary butyl alcohol B = tertiary amyl alcohol C = 2-methylbut-3-yn-2-ol It will be clearly seen from these results that the association of tertiary alcohols in accordance with the invention makes it possible to use these alcohols in amounts that are very much lower than those required when only a single alcohol is used.

The purpose ofthefollowing Examples isto illustrate but no limit the invention and to set forth its advantages.

Example 1 The following compounds were incorporated in 1,1,1-trichloroethane: tertiary butyl alcohol 1.5 tertiary amyl alcohol 2.0 1,2-butylene oxide 0.45 nitromethane 1.3 The resulting composition was tested by successive distillation. This comprises distillation four times in succession, collecting only the first 90% by volume that passes in each distillation step. The scratching test in accordance with ASTM D 2943-71 T was carried out on each of the four distillates. The above-indicated composition passed 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 Materials Testing).This test comprises carrying out three operations on a mixture of 100 cc of stabilized 1,1,1-trichloroethane and 100 cc oftoluene: operation 1: addition of 18 g of aluminium in thin sheet form 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 temperature of the bath being 114 C, for a period of 18 hours.

The stabilized 1,1,1-trichloroethane was then distilled in three equal fractions, in accordance with the standard DIN 51 751, and then operation 1 was carried out on 100 cc of each of these fractions, mixed with 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 herein before passed the test, without any violent exothermic reaction being observed.

Example 2 1,1,1-Trichloroethane containing; tertiary butyl alcohol 2.1 tertiary amyl alcohol 1.0 2-methylbut-3-yn-2-ol 0.85 1,2-butylene oxide 0.45 nitroethane 1.3 successfully passed the successive distillation and BAM tests set out in Example 1.

Example 3 1,1,1 -Trichlornethane to which the following were added: tertiary butyl alcohol 1.7% tertiary amyl alcohol 1.0% 2-methylbut-3-yn-2-ol 1.0% 1,2-butylene oxide 0.45% nitroethane 0.6% nitromethane 0.5% also successfully passed the successive distillation and BAM tests set out in Example 1.

Example 4 1,1,1 -Trichloroethane to which the following were added: tertiary butyl alcohol 1.5% tertiary amyl alcohol 2.0% 1,2-butylene oxide 0.45% nitromethane 1.3% N-methylpyrrol 0.008% also successfully passed the successive distillation and BAM tests set out in Example 1.

Example 5 In order to demonstrate the attraction of adding an amine for certain particular uses, 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 proportions 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, the pH changed from 6.7 before the testing operation to 4.5 after 72 hours' reflux (at this pH, it is known that the solvent is particularly corrosive in respect of degreasing machines).

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

Example 6 1,1,1 -Trichloroethane containing the following compounds: tertiary butyl alcohol 2.2% tertiary amyl alcohol 0.1% 2-methylbut-3-yn-2-ol 2.2% 1,2-butylene oxide 0.45% nitromethane 1.2% successfully passed the successive distillation and BAM tests set out in Example 1.

Example 7 The following composition also successfully passes the successive distillation and BAM tests set out in Example 1: 1,1,1 -trichloroethane 95.0% tertiary butyl alcohol 1.3% tertiary amyl alcohol 1.2% trioxan 1.4% 1,2-butylene oxide 0.4% nitromethane 0.7%

Claims

1. A method of stabilizing 1,1,1-trichiornethane that comprises incorporating in it, by weight bases on the weight 1,1,1-trichloroethane, 0.1 to 6% of a mixture of tertiary amyl and butyl alcohols, 0 to 3% of 2-methylbut-3-yn-2-ol, 0.1 to 5% of at least one C3.8 epoxide and/or chlorinated epoxide and 0.1 to 3% of at least one C1.3 nitroalkane, stabilized 1,1,1 -trichloroethane, the weight of the stabilizing agents concentrated in the head fractions represents from 40 to 60% of the weight of stabilizing agents concentrated in both the head fractions and the bottom fractions.

2. A method as claimed in claim 1 in which the total weight of tertiary amyl and butyl alcohols and 2-methylbut-3-yn-2-ol is 3 to 5% based on the 1,1,1-trichloroethane.

3. A method as claimed in claim 1 or 2 in which the binary mixture of tertiary butyl and tertiary amyl alcohols comprises, by weight, from 1 to 99% of tertiary butyl alcohol and from 99 to 1% of tertiary amyi alcohol.

4. A method as claimed in claim 3 in which the mixture comprises, by weight, from 25 to 80% of tertiary butyl alcohol for 75 to 20% of tertiary amyl alcohol.

5. A method as claimed in claim 1 or 2 in which the ternary mixture of tertiary butyl alcohol, tertiary amyl alcohol and 2-methylbut-3-yn-2-ol comprises, by weight, from 15 to 85% of tertiary butyl alcohol, from 1 to 50% of tertiary amyl alcohol and from 1 to 50% of 2-methylbut-3-yn-2-ol.

6. A method as claimed in claim 5 in which the ternary mixture comprises, by weight, 30 to 65% of tertiary butyl alcohol, 15 to 35% of tertiary amyl alcohol and 15 to 35% of 2-methylbut-3-yn-2-ol.

7. A method as claimed in any one of claims 1 to 6 in which the epoxide is 1,2-butylene oxide.

8. A method as claimed in any one of claims 1 to 6 in which the epoxide or chlorinated epoxide is epichlorohydrin, glycidol or its primary, secondary or tertiary butyl, methyl, ethyl, propyl, isopropyl or allyl ether, 1,2-propylene oxide, styrene oxide or cyclohexene oxide.

9. A method as claimed in any one of claims 1 to 8 in which there is also added as anti-oxident, up to 1% by weight, based on the 1,1,1 -trichloroethane, of at least one phenol and/or nitrogenous heterocycle having 1 to 2 nitrogen atoms and 3 to 5 carbon atoms with possibly an oxygen atom in the ring.

10. A method as claimed in claim 9 in which the anti-oxidant is N-methylpyrrole.

11. A method as claimed in claim 9 or 10 in which the weight of anti-oxidant is 0.001 to 0.1% of the weight of 1,1,1-trichloroethane.

12. A method as claimed in any one of claims 1 to 11 in which there is also added up to 1% by weight, based on the 1,1,1-trichloroethane, of an aliphatic amine or a nitrogenous heterocyclic compound having from 4 to 10 carbon atoms and 1 to 2 nitrogen atoms in the molecule.

13. A method as claimed in claim 12 in which the heterocyclic compound is N-methylmorpholine.

14. A method as claimed in claim 12 or 13 in which the weight of amine or heterocycle is from 0.001 to 0.1% of the weight of the 1,1 1-trichloroethane.

15. A method as claimed in any one of claims 1 to 14 in which from 0.1 to 3.5% by weight oftrioxan and/or trimethyl orthoformate is also incorporated.

16. A stabilized 1,1,1 -trichloroethane composition containing as stabilizing agents, 0.1 to 6% of a mixture of tertiary butyl alcohol and tertiary amyl alcohol, from Oto 3% of 2-methylbut-3-yn-2-ol; from 0.1 to 5% of at least one C3 8 epoxide or chlorinated epoxide and from 0.1 to 3% of at least one C1 3 nitroalkane, the said percentages being expressed by weight with respect to the 1,1,1 -trichloroethane, with the condition that, on distillation of the stabilized 1,1,1 -trichloroethane, the the weight of the stabilizing agents cencentrated in the head fractions represent from 40 to 60% of the weight of the stabilizing agents concentrated in both the head fractions and the bottom fractions.

17. A composition as claimed in claim 16 in which the total weight of tertiary amyl and butyl alcohols and 2-methylbut-3-yn-2-ol is 3to 5% based on 1,1,1-trichloroethane.

18. A composition as claimed in claim 16 or 17 in which the mixture of tertiary butyl and tertiary amyl alcohols comprises from 1 to 99% by weight of tertiary butyl alcohol and from 99 to 1% by weight of tertiary amyl alcohol.

19. A composition as claimed in claim 18 in which the said mixture comprises from 25 to 80% by weight of tertiary butyl alcohol and from 75 to 20% by weight of tertiary amyl alcohol.

20. A composition as claimed in claim 16 or 17 in which the ternary mixture of tertiary butyl alcohol, tertiary amyl alcohol and 2-methylbut-3-yn-2-ol comprises, by weight, from 15 to 85% of tertiary butyl alcohol, from 1 to 50% of tertiary anyl alcohol and from 1 to 50% of 2-methylbut-3-yn-2-ol.

21. A composition as claimed in claim 20 in which the ternary mixture comprises, by weight, 30 to 65% of tertiary butyl alcohol, 15 to 35% of tertiary amyl alcohol and 15 to 35% of 2-methylbut-3-yn-2-ol.

22. A composition as claimed in any one of claims 16 to 21 in which the epoxide is 1 ,2-butylene oxide.

23. A composition as claimed in any one of claims 16 to 21 in which the epoxide or chlorinated epoxide is epichlorohydrin, glycidol or its primary, secondary or tertiary, butyl, methyl, ethyl, propyl, isopropyl or allyl ether, 1,2-propylene oxide, styrene oxide or cyclohexene oxide.

24. A composition as claimed in any one of claims 16 to 23 further comprising, an anti-oxidant, up to 1% by weight, based on the 1,1,1 -trichloroethane, of at least one phenol and/or nitrogenous heterocycle having 1 to 2 nitrogen atoms and 3 to 5 carbon atoms with possibly an oxygen atom in the ring.

25. Rcomposition as claimed in claim 24 in which the anti-oxidant is N-methylpyrrole.

26. A composition as claimed in claim 24 or 25 in which the weight of the anti-oxidant is 0.001 to 0.1% of the weight of the 1,1,1 -trichloroethane.

27. A composition as claimed in any one of claims 16 to 26 further containing up to 1% by weight, based on the 1,1,1-trichloroethane, of an aliphatic amine or nitrogenous heterocycle having from 4to 10 carbon atoms and 1 to 2 nitrogen atoms in the molecule.

28. A composition as claimed in claim 27 in which the heterocyclic compound is N-methylmorpholine.

29. A composition as claimed in claim 27 or 28 in which the weight of amine or heterocycle is from 0.001 to 0.1% of the weight of the 1,1,1-trichloroethane.

30. A composition as claimed in any one of claims 16 to 29 that further contains from 0.1 to 3.5% by weight of trioxan and/or trimethyl orthoformate.

31. A composition as claimed in claim 16 substantially as hereinbefore described in any one of the foregoing Examples.