DE1115237B - Stabilization of trichlorethylene, perchlorethylene and similar aliphatic chlorinated hydrocarbons against decomposition - Google Patents

Description

The invention relates to the stabilization of chloroethylene, perchlorethylene and similar aliphatic Chlorinated hydrocarbons to the decomposition of these products and the simultaneous formation of Avoid acid during storage or use.

It is known that aliphatic chlorinated hydrocarbons are exposed to the action of heat and oxygen an oxidation, which by various means, such as light, and certain metal salts, ζ. Β. ι ° the salts of aluminum, iron and magnesium, is catalyzed.

In order to slow down this oxidation, it has been proposed to add small amounts to these chlorinated hydrocarbons Amounts of different products, such as alcohols, * 5 inorganic or organic basic substances, phenols, Add epoxy compounds.

Whatever the effectiveness of these stabilizers in order to avoid the oxidation of the chlorinated hydrocarbons, they can generally reduce the decomposition of these chlorinated hydrocarbons during their use not prevent.

Indeed, the addition of a single stabilizing compound is generally insufficient for the Avoid degradation of the chlorinated hydrocarbons.

Even the addition of several stabilizing compounds does not always lead to the desired result Result, be it because of their intolerance or because too large quantities of these products are necessary to ensure good stabilization.

The invention relates to a new combination of stabilizing reactants for such chlorinated hydrocarbons, which leads to surprising results.

The invention therefore consists in the use of a mixture of one or more primary Pentanols with a heterocyclic nitrogen base to stabilize trichlorethylene, perchlorethylene and similar aliphatic chlorinated hydrocarbons against decomposition. Suitable nitrogen bases are Pyridine, α-picoline (2-methylpyridine), morpholine (tetrahydro-1,4-oxazine). It is preferable to choose-picoline. Among the primary pentanols can be mentioned: primary normal amyl alcohol, primary Isoamyl alcohol or 3-methyl-butanol-1, primary optically active amyl alcohol or 2-methyl-butanol-l. An example of a mixture of primary pentanols is the fermentation amyl alcohol, which is essentially contains primary isoamyl alcohol and optically active primary amyl alcohol.

It has been found that the alcohols as well as the nitrogen bases, each group applied individually, stabilization of trichlorethylene,
Perchlorethylene and similar aliphatic chlorinated hydrocarbons against decomposition

Applicant:
Solvay & Cie., Brussels

Representative: Dr.-Ing. A. van der Werth, patent attorney, Hamburg-Harburg 1, Wilstorfer Str. 32

Claimed priority:
Belgium of 10 September 1958 (no.571104)

Nestor Daras, Ixelles, Brussels,

and Andre Ryckaert, Uccle, Brussels (Belgium),

have been named as inventors

do not ensure the stabilization of aliphatic chlorinated hydrocarbons even in increased quantities can, but that the combination of these compounds results in a decidedly synergistic and unexpected Effect leads.

The stabilizing effect of the compounds used to improve resistance of chlorinated hydrocarbons against decomposition is proven by the following laboratory test:

200 ecm of perchlorethylene to which the stabilizers investigated have been added into an Erlenmeyer flask of 500 ecm with a straight rising and fed with water Cooler introduced. A thin tube of 3 mm inside diameter, which goes into the flask to 6 mm across protrudes into the ground, enables oxygen to be conducted into and through the perchlorethylene. A sample tube made of steel is hung from this pipe at the end of the radiator, and another smaller one lies at the bottom of the Piston.

The introduction of oxygen is done at ten to twelve bubbles per minute via a water seal immersing pipe regulated. This bubble counter is placed in front of the experimental apparatus.

109 709/416

The perchlorethylene is refluxed for 48 hours by heating by means of a 150 watt lamp made of frosted glass. The lamp is in a stainless steel cylinder 190 mm high and 100 mm inner diameter firmly arranged. The thickness of the steel is 1 mm. This The cylinder is covered in its upper part by a ring of 132 mm outer diameter, 82 mm inner Diameter and 2 mm thick. The bottom of the piston, which is arranged on this ring, is thus 30 mm away from the lamp. Four diametrically opposed openings from 40 mm high and 20 mm wide are drilled in the lower part of the cylinder to allow some ventilation the apparatus.

Since the strength of the lamp is insufficient to ensure regular boiling of the perchlorethylene, it is advisable to protect the device against heat loss. The Erlenmeyer flask is for this purpose of a jacket made of a glass cylinder with an internal diameter of 121 mm, a height of 147 mm and a thickness of 3 mm surrounded, which is provided inside and outside with asbestos paper and filled with glass wool. The whole is of a square box made of asbestos cardboard with a hole in the middle for the passage of the Surrounding the neck of the flask. This thermal protection reduces heat losses to a minimum and allows regular boiling of perchlorethylene and improves reproduction the Results.

At the end of the experiment, a 50 ccm sample is stirred with 100 ecm of water for 3 minutes. One titrates the solid acidity with NaOH in the presence of bromocresol green. The results are in percent by weight Hydrochloric acid and allow the effectiveness of the stabilizers tested to be compared.

The following table shows the influence of the alcohols, including the primary pentanols and or or the nitrogen bases on the stability of the Perchlorethylene.

Vf »r- Stabilizers ccm / 1 Educated VCi "
search-
number _ _ Acidity in
Weight
percent HCl 1 normal amyl alcohol 500 0.0640 2 Fermentation amyl alcohol 500 0.0068 3 tert. Amyl alcohol 500 0.0280 4th Isobutyl alcohol 500 0.0220 5 "- Picoline 100 0.0126 6th Morpholine 100 0.0140 7th Pyridine 100 0.0261 8th normal amyl alcohol
(500 mg / l) + «-picoline
(100 mg / 1) 0.0288 9 normal amyl alcohol
(500 mg / l) + morpho
lin (100 mg / 1) 0.0005 10 normal amyl alcohol
(500 mg / l) + pyridine
(100 mg / 1) 0.0044 11 0.0066

Ver Stabilizers ccm / 1 Educated search- Acidity in
Weight number tert. Amyl alcohol percent HCl 5 12th (500 mg / l) + α-picoline 0.0260 (100 mg / 1) tert. Amyl alcohol IO 13th (500 mg / l) + morpho 0.0510 lin (100 mg / 1) tert. Amyl alcohol 14th (500 mg / l) + pyridine 0.0440 (100 mg / 1) 15th Fermentation amyl alcohol 15th (500 mg / l) + «-picoline 0.0022 (100 mg / 1) prim. Isobutyl alcohol 20th 16 (500 mg / l) + «-picoline 0.0153 (100 mg / 1) prim. Isobutyl alcohol 17th (500 mg / l) + morpho 0.0490 lin (100 mg / 1) 25th prim. Isobutyl alcohol 18th (500 mg / l) + pyridine 0.0090 (100 mg / 1)

The results show that the alcohols including the primary pentanols and the nitrogen base not even with increased addition alone ensure the stabilization of chlorinated hydrocarbons can.

In contrast, the combination of the primary pentanols and the nitrogen bases offers one represent a considerable synergistic effect, especially in the case of the combination with α-picoline.

The amount of stabilizers to be used according to the invention can in general, based on 11 hydrocarbon to be stabilized, between 0.1 to 10 g for the primary pentanols and 0.05 to 0.5 g for the nitrogen bases. Used preferably 0.3 to 2 g of pentanol and 0.1 to 0.2 g of nitrogen base per 1 liter of chlorinated hydrocarbon.

It has also been found that, where appropriate, the stabilizing effect of the described Combinations can improve if amounts between 0.005 and 0.02 g of a phenol, e.g. B. phenol, Cresol, thymol added per 11 chlorinated hydrocarbon.

Although the compositions described are particularly effective in the case of stabilizing Perchlorethylene have proven, they can also be used for the stabilization of other chlorinated solvents, such as trichlorethylene, carbon tetrachloride, dichloroethane, trichloroethane, can be used.

Claims (5)

PATENT CLAIMS: 1. Use of a mixture of one or more primary pentanols with a heterocyclic one Nitrogen base for stabilizing trichlorethylene, perchlorethylene and the like aliphatic chlorinated hydrocarbons against decomposition. 2. Embodiment according to claim 1, characterized in that mixtures of small amounts of one or more primary pentanols from the group of normal primary amyl alcohol, optically active amyl alcohol, isoamyl alcohol and a heterocyclic nitrogen base from the group «-picoline, pyridine, morpholine are used. 3. Embodiment according to claim 1 and 2, characterized in that 0.1 to 10 g primary Pentanol and 0.05-0.5 g heterocyclic nitrogen base per 11 chlorohydrocarbon used will. 4. Embodiment according to claim 1 to 3, characterized in that 0.3 to 2 g primary Pentanol and 0.1 to 0.2 g of heterocyclic nitrogen base per 11 perchlorethylene are used. 5. Embodiment according to claim 1 to 4, characterized in that also low Amounts of a phenol can be used. © 109 709/416 10.