US2252099A

US2252099A - Manufacture of aromatic nitrogen compounds

Info

Publication number: US2252099A
Application number: US230781A
Authority: US
Inventors: Rosen Raphael
Original assignee: Standard Oil Development Co
Current assignee: Standard Oil Development Co
Priority date: 1938-09-20
Filing date: 1938-09-20
Publication date: 1941-08-12
Anticipated expiration: 1958-08-12

Description

Patented Au 32, 1941 MANUFACTURE OF AROMATIC NITRGGEN COMPOUNDS Raphael Rosen, Elizabeth, N. J., assignor to Standard @il Development Company, a corporation of Delaware No Drawing. Application September 20, 1938, Serial No. 230,781

8 Claims.

This invention relates to novel products rich in aromatic nitrogen compounds and methods of preparing and using the same. More particularly, it relates to the nitration of certain petroleum hydrocarbon liquids rich in aromatic hydrocarbons to form a mixture of aromatic nitro compounds, as Well as the subsequent reduction the nitro compounds to the corresponding a1 matic amines, which have been foundto have exceptionally high anti-knock properties for use.

in motor fuels.

By the method of the present invention, pe troleum hydrocarbon fractions and products derived therefrom by simple physical treatment,

- such as solvent extraction, may be used as the raw materials for the formation of aromatic nitro compounds or aromatic. amines of high quality and in good yields. The mixture of nitro compounds, formed in the early stages of the process, may be separated from non-aromatic material and further treated for the separation of the individual nitro compounds, or the mixture may be reduced as such, either in the presence or absence of parafiinic material, to form a mixture of amines, which may in turn be treated for the separation of the individual aromatic amines, or the mixture of amines may be used as such as a valuable anti-knock agent in motor fuels.

It has now been found that a high yield and a high quality product may be obtained if one selects as the material to be nitrated a petroleum hydrocarbonliquid substantially free from oleflns, because it has been found that due to their olefinic structure these compounds interfere with the desired nitration of aromatic compounds, by

, reason of the fact that the olefins undergo oxidation and other side'reactions much more easily than the aromatic hydrocarbons and hence require the consumption of an excessively large amount of nitrating agent in order to accomplish the desired result. Furthermore, when oxidation products thus formed are present during the second or hydrogenation step, an excessive amount of hydrogenating material is necessary;

and finally when olefins are present in the starting material, the finished product (after hydrogenation) has lower anti-knock properties than the product resulting from the treatment of an original raw material rich in aromatics, but substantially free from olefins.

It has been proposed in the Ihrig U. S. Patent 1,844,362 to produce aromatic amines by first extracting a petroleum fraction containing aromatic and hydroaromatic hydrocarbons as well as olefins with a polar solvent to concentrate the aromatic, hydroaromatic and unsaturated compounds, then separating from the extract the unsaturated compounds by treatment with sulfuric acid, and finally nitrating and reducing to produce a mixture of amines. This method has the disadvantage that the sulfuric acid treatment removes not only the olefins but also a considerable proportion of the valuable aromatic hydrocarbons as well. It is well known that benzene, toluene, and the xylenes dissolve readily in strong sulfuric acid. It has, in fact, been found that benzene, toluene, and mixed xylenes are, respectively, 27%, and 98% soluble in 93% sulfuric acid in 10 minutes of contact. (J. Inst. Petr. TechnoL, vol. 17 (1931), page 140.) Furthermore, aromatic hydrocarbons, such as toluene, have been found to be very readily attacked by sulfuric acid in the presence of olefins. (Gurwitsch and Moore, The Scientific Principles of Petroleum Technology (1932), page 393.) It is evident, therefore, that the 93% sulfuric acid employed in the process of the Ihrig patent would dissolve considerable quantities of the aromatic hydrocarbons from the sulfur dioxide extracts containing high concentrations of the aromatics and olefins.

The sulfuric acid treatment, moreover, is not efllcient in removing all of the olefinic material from the oil. It has been found that sulfuric acid causes considerable polymerization of olefins and that the polymerization products are unsaturated and dissolve in the oil layer, rather than the acid layer. (Gurwitsch and Moore, ibid., page 395.) within the oil considerable quantities of unsaturated olefinic material which would absorb a part of the nitrating acid and occasion other disadvantageous results hereinbefore discussed.

The presentinvention avoids these disadvantages by selecting as the initial raw material for the preparation of nitro compounds and amines a petroleum hydrocarbon liquid, which is rich in aromatics but substantially free from olefinic hydrocarbons and therefore requires no treatment with sulfuric acid. As suitable materials one may use straight-run aromatic rich petroleum distillates derived from crude petroleum containing relatively large amounts of aromatic hydrocarbons but substantially no olefins, such as the crudes obtained from the Conroe, Deep Sand Raccoon Bend, Shallow Sand Raccoon Bend, or Tomball fields; or one may use liquids resulting from a hydrogenation treatment of a highly aromatic cracked petroleum fraction containing ole- Thus the acid treatment would still leave I conditions tending to produce primarily mono- A nitrated derivatives as the nitration is completed, in order that the amines resulting from the reduction of the nitro compounds will have boiling points within the gasoline boiling range, also to avoid the formation of explosive poly-nitrated derivatives. For this purpose, temperatures not substantially above room temperatures and proportions of nitric acid not greatly in excess of that required for producing the mono-nitrated derivatives are used.

The resulting nitro derivatives may, if desired, be segregated from any non-aromatic constituents present, such as paraffinic hydrocarbons (which do not react with the nitrating agent), by any suitable means, for example, by washing or extraction with a suitable selective solvent therefor, such as ether, or any other suitable treatment which will cause the separation of the mixed liquid into two distinct layers of difierent gravity. Poly-nitrates, if present, may be removed from the nitrate layer by washing and steam distilling the latter. The individual nitro compounds composing the mixture may be separated, if desired, by any convenient process, e. g., distillation under reduced pressure.

The aromatic nitro compounds thus obtained, either free from or still in admixture with paraffinic compounds, may, if desired, be reduced or hydrogenated by any suitable means, such as by the use of finely divided iron in the presence of a small amount of acid, or by treatment with a gas rich in hydrogen in the presence of a hydrogenation catalyst, such as a finely divided active nickel catalyst, formed, for example, by the reduction of nickel oxide or by dissolving out aluminum or silicon from an alloy of nickel with aluminum or silicon by means of sodium hydroxide. The resulting aromatic amines may either be used while still in admixture with unreacted nonaromatic compounds or may be separated therefrom by steam distillation or by the formation of their salts and subsequent liberation of the amines by distillation or by suitable extraction methods, and may finally be distilled to a desired boiling range, for instance, 40-225 C., if the product is to be used as an anti-knock agent in.

motor fuels, or, if the individual amines are desired as end products, these may be separated from the mixture by any suitable means.

As illustrations of suitable methods of carrying out the invention, the following examples are given:

Example I A. naphtha cut, having a boiling range of 99-193 0., obtained from a mixture of aromatic South Texas crude petroleum oils containing substantially no oleflns, was extracted with liquid sulfur dioxide. The resulting extract exhibited a boiling range of 93-146 C. and an A. P. I. gravity of 36.4, and contained approximately 85% aromatic hydrocarbons. To 10 parts by volume of this extract was added 16 parts by volume of a mixture of equal parts of concentrated nitric and concentrated sulfuric acid at a temperature of -10 to 0 C., with agitation of the mixture. After a continued agitation at this temperature for 1 /2 hours, the mixture was poured into 200 parts by volume of ice water, whereby separation of the acid was eifected.

The mixture of nitrated compounds and unreacted hydrocarbons was reduced by treatment with iron filings and hydrochloric acid at -90" (2., with rapid stirring, for about 1 hour. The resulting amines were separated by distillation with steam and redistilled at 202218 C. A yield of approximately 73%, based on the amount of aromatic hydrocarbons present in the nitrating mixture, was obtained.

Example II One part by volume of a nitrated sulfur dioxide extract of an aromatic type petroleum hydrocarbon liquid, obtained as in Example I, was dissolved in two partsby volume of ethyl alcohol. About 10 grams of a finely divided active nickel catalyst was added for each cubic centimeters of solution, and hydrogen was passed in under four pounds pressure, with agitation. The temperature rose to about 50 C., and reduction was complete at the end of two hours. A similar test showed that the hydrogenation could be conducted equally well without dissolving the nitrated product in alcohol.

The amines present in the product of the hydrogenation step may be separated and purified by the methods described in Example I.

A mixture of aromatic amines produced by the method of Example I was tested to determine its anti-knock characteristics when blended with gasoline motor fuels. The tests were conducted both by the method of the American Society for Testing Materials (C. F. R. engine), test desig nation D435'7-3'7T (A. S. T. M. Standards on Petroleum Products and Lubricants), and by the method of the U. S. Army Air Corps (U. S. Army Specification 2-94). The results of these tests are set forth in Table I.

Table I U. 8. Army T t A. S. T. M. method method g Blend No. 1 cc. Blend. No. Blend. lead lead value lead value 1 Gasoline .v 15 32.5 2 Ditto plus 4% 73 o amines 82. 1 87. 3 252 3 Dittoin plus 7.5% 84- a as 5 202 4 Ditto plus 15% 86 0 240 a as 88.0 16 5 Gasoline 13"--. 085.6 2 (129.2 188 6 Ditto plus 5% amines 89 153 o Inter-pointed value. H h grade gasoline motor fuel.

"B end of gasoline containing about 42% isopropyl ether.

lead tetraethyl per U. S.

lhe blending value of the amines is calculated by the following formula:

Ograx 12) Blending va1ue= FA where 'creases the octane number of non-leaded as well as leaded gasolines, and that these amines also have unusually high blending values.

It is not intended that the invention be limited to the particular examples, modifications, and embodiments of the invention, which have been given merely for the sake of illustration, but only by the appended claims, in which it is intended to claim all novelty inherent in the invention as broadly as the prior art permits.

I claim:

1. The process for preparing a composition containing a large proportion of nitro derivatives of aromatic hydrocarbons which comprises extracting with sulfur dioxide a naphtha fraction of petroleum rich in aromatic hydrocarbons, but substantially free from olefins, treating the resulting extract with a mixture of nitric and sulfuric acids, and separating the nitro compounds formed from the non-aromatic material present.

' 2. The process for preparing a composition containing a large proportion of mono-nitrated derivatives of aromatic hydrocarbons which comprises treating a petroleum hydrocarbon liquid rich in aromatic hydrocarbons, but substantially free from olefins, with a suflicient quantity of a mixture of nitric and sulfuric acids to react with all of the aromatic hydrocarbons present, but to form substantially only mono-nitrated derivatives therewith, at a temperature not sub-- stantially above room temperature, and separating the nitro compounds formed from the nonaromatic material present.

3. The process for preparing a composition containing a large proportionof nitro derivatives of aromatic hydrocarbons which comprises ex tracting with sulfur dioxide a naphthafraction of a petroleum rich in aromatic hydrocarbons, but substantially free from olefins, and having a boiling range of approximately 99-193 0., treating the resulting extract with a mixture of approximately equal parts of nitric and sulfuric acids at approximately to 0' C., and separating the nitro compounds formed from the non-aromatic material present.

-4. In the process of preparing a composition containing a large proportion of aromatic amines and adapted to be used as an anti-knock blending agent for motor fuels, by nitrating a hydrocarbon mixture containing a substantial pro portion of aromatic hydrocarbons and reducing the aromatic nitro compounds thus formed to aromatic amines, the steps which comprise extracting a naphtha fraction of petroleum rich in aromatic hydrocarbons, but substantially free from olefins, with a solvent having a substantially greater solvent power for aromatic hydrocarbons than for paraffinic hydrocarbons, and removing said solvent from the extracted material prior to the nitration step.

5. In the process of preparing ,a composition containing a large proportion of aromatic amines and adapted to be used as an anti-knock blending agent for motor fuels, by nitrating a hydrocarbon mixture containing a substantial proportion of aromatic hydrocarbons and reducing the aromatic nitro compounds thus formed to aromatic amines, the steps which comprise extracting a naphtha fraction of a virgin petroleum hydrocarbon liquid rich in aromatic hydrocarbons, but substantially free from olefins, with sulfur dioxide, and removing said sulfur dioxide from the extracted material prior to the nitration step. i

6. In the process of preparing a composition containing a large proportion of aromatic amines and adapted to be used as an anti-knock blending agent for motor fuels, by nitrating a hydrocarbon mixture containing a substantial proportion of aromatic hydrocarbons and reducing the aromatic nitro compound thus formed to aromatic amines, the steps which comprise extracting a naphtha fraction of a petroleum rich in aromatic hydrocarbons, but substantially free from olefins, and having a boiling range of approximately 99-193 0., with sulfur dioxide, and removing said sulfur dioxide from the extracted material prior to the nitration step.

7. In the process of preparing a composition containing a large proportion of nitro derivatives of aromatic hydrocarbons by nitrating a hydrocarbon mixture, the steps which comprise extracting a naphtha fraction of petroleum rich in aromatic hydrocarbons, but substantially free from olefins, with a solvent having a substantially greater solvent power for aromatic hydrocarbons than for parafiinic hydrocarbons, and removing said solvent from the extracted material prior to' the nitration step.

8. In the process for preparing a composition containing a large proportion of nitro derivatives of aromatic hydrocarbons by nitrating a hydrocarbon mixture, the steps which comprise extracting a virgin petroleum hydrocarbon liquid rich in aromatic hydrocarbons, but

substantially free from olefins, with a solvent having a substantially greater solvent power for aromatic hydrocarbons than forparafiinic hydrocarbons, and removing said solvent from the extracted material prior to the nitration step.

RAPHAEL ROSEN'.