DE927165C - Antioxidants - Google Patents

Description

(WiGBI. P. 175)

ISSUED MAY 2, 1955

/ 4517 IVd 123 b

The invention relates to stabilizers against oxidation, peroxidation, polymerisation and resin formation in gasoline and the like Links.

Liquid aldehydes tend to form the corresponding acids when exposed to air. This oxidation can be used regardless of the type of container material in which the aldehyde is stored will take place and can be accelerated by this.

In a similar way, ethers tend to form peroxides and / or hydroperoxides when stored.

Acid evolution in an aldehyde can cause storage problems and can also be disadvantageous in some processes in which aldehydes are to be used, e.g. B.

in the manufacture of synthetic resins or in the hydrogenation to an alcohol. The ether peroxidation is therefore undesirable because ether peroxides are mostly highly explosive.

In addition, it can cause the oxidation of hydrocarbons, such as those in gasoline and lubricating oils present, lead to the formation of acids and resin, which reduce the material or make it unusable do. Animal and vegetable oils are created by the formation of acids by atmospheric Oxidation rancid.

It has already been suggested that N, N'-di-alkylp-phenylenediamine to use as a means of inhibiting these undesirable / reactions.

It has now been found that N, N'-di-alkylm-phenylenediamines are particularly effective for this purpose and these reactions are essential

prevent if at least one of these compounds is present in the substance to be protected. The amount required for this can vary within a wide range and depends on the type of substance to be protected and the. Conditions to which it is subjected. For example, the addition of ο, οοι to I ⁰ Zo of these inhibitors, calculated on the weight of the substance to be stabilized, is generally beneficial for compounds such as benzines, aldehydes,

z. B. nonaldehydes, fatty oils, vegetable oils, lubricants and ethers, e.g. B. tetrahydrofuran), In the following examples the preparation

some new compounds to be used as stabilizers according to the invention are described, no protection is claimed for these manufacturing processes. There are N, N'-dialkyl-m-phemylenediamines from m-phenylenediamine, m-nitroaniline or m-di-nitrobeneol in the presence a ketone such as acetone or an aldehyde as a solvent and alkylating agent.

Example i

2.5 g of m-nitroaniline in 300 ecm of acetone were hydrogenated in an autoclave in the presence of a catalyst consisting of platinum on charcoal which contained 30 percent by weight of platinum under a hydrogen pressure of 40 to 50 atm, the temperature being reduced to 100 for 1 hour Was held at ' ⁰ ' and then at 160 ° for a further 8 hours.

The catalyst and excess solvent were then removed from the product and the latter is distilled under reduced pressure.

There were 7.1 g of in 135 ^'01 at 1 mm pressure boiling material obtained and 19 g of a main fraction boiling at 1 mm, the pressure at 135-136 ^0th The latter represented 67% of the theoretical yield. It was identified as an N, N'-diHsopropylm-pihenylendiamiine. In the case of the dibenzoyl derivative with a melting point of 137 ^° , a carbon content of 78.2%, a hydrogen content of 7% and a nitrogen content of 7.1% were found. This agrees excellently with the calculated percentages for C ₂₆ H ₂₈ N ₂ O ₂ of 78% carbon, 7% hydrogen and 7% fuel.

Example 2

100 g of m-dinitrobenzene in 400 ecm of acetone were reacted at room temperature under a hydrogen pressure of 40 to 50 atm in the presence of 5 g of a platinum-on-charcoal catalyst containing 5 percent by weight of platinum until the hydrogen absorption ceased, and then another 8 Hours at 160 ° ^C. under otherwise unchanged conditions. 90.4 g of a crude product were formed which, as was shown in the fractionation and the formation of derivatives, was essentially the desired N, N'-di-isopropyl-m The dibenzoate (see Example 1) had a melting point of 136 to 137 ^a . The hydrochloride crystallized from methanol or acetone in prismatic needles with a melting point of 25 2 °, at which the decomposition then began contained 54.8% C, 6g 8.4% H, 10.3% N and 26.6% Cl, which was in excellent _{agreement with the values required for C 12} H ₂₀ N ₂ · 2 HCl (54.3% C, 8.3% H, 10.6% N and 26.8% Cl).

In general, it was found to be advantageous to carry out the first hydrogenation stage at temperatures below ⁰ ioo ', wherein, preferably the reaction vessel, no heat should be supplied when nitro compounds as starting materials! be used.

Example 3

60 g m-Phenylendiamio, which were dissolved in 180 cc of acetone was added 8 hours in the presence of 3 g of platinum on charcoal existing catalyst comprising 30 weight percent of platinum contained, at under a hydrogen pressure of 40 to 50 and reacted at ioo ^Oi. 84.6% of a crude product was obtained. This in turn had a substantial content of the desired N, N'-di-isopropyl-m-phenylenediamine, which was finally obtained in the pure state by conversion to the dihydrochloride and recovery of the free base from the crystallized acidic salt. The pure free base was found in the distillation as a clear, colorless, mobile liquid with a refractive index nf of 1.5501 and a boiling point of 108 to no ¹⁰ at 75 mm abs. Pressure found. The analysis found 74.9% C, 10.4% H and 14.8% N, which is excellent with those for C ₁₂ H ₂₀ N ₂ (75 ⁰ ZoC, 10.4% H and 14.6 ⁰ ZoN ) required values matched.

Example 4

26 gm - nitranilimi, dissolved in 300 ecm methyl ethyl ketone, were treated as in Example 1. After removing the catalyst and the excess solvent, the crude product was distilled under reduced pressure. There were 1.5 g of one under an abs. Pressure of 0.5 mm at 60 to 120 ' ⁰ boiling material and a main fraction of 2 (2i, 5 g, which ^{boils under an absolute pressure of 0.5 mm at 120 to 130 0} '. This last fraction was called N, N'-di-sec-butyl-m-phenylenediamine identified. The auskristalHsierende from aqueous alcohol dibenzoate \ melted at 120 to i2i ° and contained 78.1 ⁰ ZOC, 7.3 ⁰ ZOH and 6.6 ⁰ Zon, which was in excellent agreement with the values required _{for C 28} H ₃₂ N ₂ O ₂ (78.5 ⁰ Zo C, 7.5 ⁰ Zo H and 6.6 ^{0 Zo N).}

N, N'-di-isopropyl-m-phenylenediamine and N, N'-di-sec-butyl-m-phenylenediamine are to be regarded as new connections. They were on antioxidant Properties studied and recognized as extremely effective inhibitors.

Moles of N, N'-di-isopropyl and N, N'-di-

3000

sec-butyl-m-phenylenediamines were each too ecm nonaldehyde (3, 5, 5-trimethylhexanal) ; e added. Acid formation, measured in milligrams

Potash lye per gram of liquid increased as follows:

Without addition

After adding
N, N'-di-isopropylm-phenylenediamine.

After adding

N, N'-di-sec-butyl-

m-phenylenediamine

Acid value

(Milligrams KOH per gram)

Days

Days

243

17 days

310

IO

31

Days

333

The products were further examined for their properties as inhibitors in the Gum formation in gasoline from the test procedure of the American Society for Testing Materials under the designation D 525/49 (9. ASTM Standards 1949, Part 5, pp. 930-933) as follows: Samples of a cracked gasoline containing 0.03 percent by weight Containing inhibitors were tested, as was a sample of cracked gasoline without admixture. The following results were achieved:

Without addition

After adding N, N'-di-isopropyl-m-phenylenediamine

After adding N, N'-di-sec-butyl-m-phenylenediamine

Induction time (minutes) according to ASTM D 525/49

45 165 150

The further experiments that followed showed that the inhibitory effect by a larger proportion of the Inhibitor can be increased. Samples of cracked gasoline that are a) 0.08 percent by weight N, N'-di-isopropyl-m-phenylenediamine and b) 0.04 percent by weight of N, N '- di - isopropyl - m -phenylenediamine, were obtained by the of the American Society for Testing Materials under the designation D 525/46 (see ASTM Standards 1946, Part III a, "pp. 251 to 254) In addition, a sample of cracked gasoline was examined without admixture. The following Results were obtained:

Without addition

After adding N, N'-di-isopropyl-m-phenylenediamine

Induction time
(Minutes) after
ASTM D 525/46

(a)

(b)

30th

435
225

Claims (2)

Patent claims: 1. Use of at least one N, N'-dialkyl-m-phenylenediamine in a small amount, e.g. B. from 0.001 to 1 weight percent as an antioxidant as well as a means against resin formation or polymerization in aldehydes, ethers, animal or vegetable oils, Waxes, lubricating oils, petroleum derivatives or polymerizable materials. 2. Use of N, N'-di-isopropyl m-phenylenediamine and / or N, N'-disec.-butyl-m-phenylenediamine according to Claim 1. Q 9623 4.55