DE10055646A1 - Oxidation of highly reactive polyisobutene used for motor fuels and lubricants comprises using a nitrogenated oxidizing agent in a ratio of polyisobutene to oxidizing agent of 1:1 to below 1:2 - Google Patents

Abstract

Oxidation of highly reactive polyisobutene comprises using a nitrogenated oxidizing agent in a ratio of polyisobutene to oxidizing agent of 1:1 to below 1:2, giving a high degree of functionalization. Oxidation of highly reactive polyisobutene comprises using a nitrogenated oxidizing agent in a ratio of polyisobutene to oxidizing agent of 1:1 to below 1:2. Independent claims are included for a functionalized polyisobutene mixture and the preparation of polyisobutene amines by catalytically hydrogenating the obtained polyisobutene.

Description

The present invention relates to a method for oxidation of highly reactive polyisobutene with a nitrogen oxide-containing oxi dans, the use of the polyisobutene derivatives thus prepared for the production of detergent additives for power and lubricants substances and additive concentrates.

Carburetor and intake system of gasoline engines, but also injection systems for fuel metering in petrol and diesel engines, are contaminated by contaminants caused by dust particles from the air, unburned hydrocarbon residues from the burner space and the crankshaft housings led into the carburetor ventilation gases are caused.

The residues shift the air-fuel ratio in the empty run and in the lower part-load range so that the mixture is richer, the combustion is incomplete and again the proportions are not burned or partially burned hydrocarbons in the exhaust gas larger and gasoline consumption increases.

It is known to avoid these disadvantages of fuel additives for keeping valves and carburettors clean or on spray systems are used (M. Rossenbeck in catalysts, Surfactants, mineral oil additives, ed. J. Falbe, U. Hasserodt, Pp. 223f., G. Thieme Verlag, Stuttgart, 1978).

Depending on the mode of action, but also on the preferred site of action Such detergent additives are now differentiated into two generations such aids.

The first generation of additives was only able to form deposits Prevent conditions in the intake system, but not existing conditions Remove storage again, whereas the additives of the second Generation can do both ("keep-clean" and "clean-up" Effect ") because of its excellent thermal stability, in particular also at zones of higher temperatures, namely at the Intake valves.  

The molecular principle of fuel detergents can ver are given more generally as a combination of polar structures with mostly higher molecular weight, non-polar or lipophilic residues.

Representatives of the second generation of additives are often products on the Basis of polyisobutenes in the non-polar part of the molecule. Here again Additives of the polyisobutylamine type are particularly noteworthy.

In US 3,576,742, reaction products are branched long-chain aliphatic olefins, for example polypropylene, Polyisobutylene or copolymers of ethylene and isobutylene, and Nitrogen oxides described. These olefins are conventional len polymerization methods from lower olefins with 2 to 6 C- Atoms made. In the obtained nitro group containing Um the presence of other functional products Groups such as hydroxyl, nitroso, nitrate, nitrite or carbonyl, supposed. The relative proportions of these groups are unknown. The structure and composition of these olefins is therefore undefined ned.

DE-C 27 02 604 describes a manufacturing process for polyisobu tene with an average degree of polymerization of 10 to 100 be wrote with the first highly reactive polyisobutenes, d. H. those with predominantly terminal double bonds become. The according to conventional polymerization methods as in US Pat. No. 3,576,742, on the other hand, have one only a small proportion of terminal double bonds.

WO 96/03367 discloses fuel and lubricant additives which by implementing the hochreak described in DE-C 27 02 604 tive polyisobutenes with nitrogen oxides or mixtures of nitrogen oxides and oxygen are obtained. As a suitable ratio of Polyisobutene and nitrogen oxide will have a molar ratio of 1: 2.2 to 1: 3, 3 suggested. A disadvantage of this method is that the Excess nitrogen oxide either by stripping with inert gas or must be removed by washing with water. The one there in the event of environmentally hazardous exhaust gases or waste water are laboriously cleaned or disposed of.

The present invention was therefore based on the object Process for the preparation of polyisobutene derivatives by oxida tion with nitrogen oxides that is simple and environmentally friendly is easy to carry out and the high degree of functionalization loot guaranteed. In particular, the procedure is said to the oxidation requires as few purification steps as possible be and not environmentally harmful and difficult to dispose of  Exhaust gases or waste water occur. In addition, the polyisobutene derivative have a defined structure and composition.

The object is surprisingly achieved by a method in which the highly reactive polyisobutene and the nitrogen oxide oxi dans in a molar ratio of 1: 1 to <1: 2, preferably 1: 1.5 to 1: 1.95, in particular 1: 1.7 to 1: 1.9.

It was surprising that a high functionalization yield of the polyisobutene used was achieved in this way, whether a deficit of nitrogen oxide is used, based on the formal stoichiometry of the reaction - the double bond in the polyisobutene should formally react with two NO ₂ molecules.

The polyisobutene derivatives which are oxidatively functionalized with NO ₂ groups and which can be obtained by the process according to the invention can be converted into polyisobutenamines by customary methods, for example by hydrogenation, the action of which is known as detergent additives in fuel and lubricant compositions and which in turn is used in further strength agents. and lubricant additives can be converted, e.g. B. by alkoxylation of the amino group with alkylene oxides such as ethylene oxide and propylene oxide.

The highly reactive polyisobutene used in the process according to the invention has olefinic double bonds with a higher reactivity than conventional polyisobutene. This higher reactivity is generally attributed to a higher proportion of polyisobutene molecules with a terminal double bond. The reactivity of a polyisobutene can be quantified, for example, by reacting it with maleic anhydride. Basically, maleic anhydride reacts with olefinic double bonds in the sense of an addition reaction. If you react polyisobutene with maleic anhydride, this addition reaction takes place practically exclusively on double bonds which have a vinylidene structure (H ₂ C = C <) (α double bond). At other double bonds in the polyisobutene, which are formed by other chain break mechanisms or by hydride shift in the polyisobutene production, are much less reactive or completely inert. Since the polyisobutene is generally used in the form of mixtures of various double bond isomers for derivatization, it is expedient to use polyisobutene with high proportions of highly reactive double bonds. This can be quantified by the value E in percent, which corresponds to the proportion of double bonds that react with maleic anhydride. The theoretical calculation value of E = 100% means that each polyisobutene molecule contains such a reactive double bond. E can be determined in a simple and most reliable manner directly from the acid number of the polyisobutene / maleic anhydride adduct.

For the process according to the invention, as a rule, they become highly crazy tive polyisobutenes with a proportion E of <60%, preferred <70%, in particular <80% and particularly preferably <90% sets, e.g. B. Polyisobutenes with E of about 75%.

According to the invention, the term polyisobutenes includes not only the homopolymers of isobutene, but also its copolymers with at least 80% by weight, preferably at least 90% by weight, of isobutene. The other olefinically unsaturated C ₄ hydrocarbons come into consideration as comonomers, so that polyisobutenes can be used in the process according to the invention which are produced by polymerization of so-called C ₄ cuts. In addition to 12 to 14% butanes, 40 to 55% butenes and up to 1% butadiene, these contain only 35 to 45% isobutene, but the largely selective polymerizability of isobutene means that the other monomers under the polymerisation conditions are only too approximate 2 to 20% are built into the polymer. Other suitable comonomers are C ₃ monomers such as propene and ethylene or a mixture thereof or with C ₄ olefins.

Depending on the intended application, the desired one Detergent additives usually become a polyisobutene with egg a number average molecular weight in the range of 300 to 20,000 Use Dalton, preferably 500 to 15000 Dalton. The middle lere degree of polymerization P in the inventive method Accordingly, the polyisobutenes used are generally in the Range from 5 to 300, preferably in the range from 10 to 250, z. B. 10 to 100. As a rule, polyisobutene derivatives with a number average molecular weight up to about 5000 daltons for the production of fuel additives, polyisobutenes with a number average molecular weight of 3000 daltons and higher Manufacture of lubricant additives used. For the production of fuel additives are therefore preferably polyisobutenes with a number average molecular weight in the range of 400 to 3500 Dalton and especially 500 to 2500 Dalton used. to Manufacture of lubricant additives are preferably poly isobutenes with a molecular weight in the range of 3000 to 15000 daltons and particularly preferably 5000 to 12500 daltons puts.

Due to their production, polyisobutenes generally have a certain non-uniformity or polydispersity. This means the quotient of the weight average molecular weight (M _W ) and the number average molecular weight (M _N ), ie M _W / M _N. With the method according to the invention, highly reactive polyisobutenes can be oxidized to polyisobutene derivatives practically independently of their poly dispersity.

For many applications, however, it is advantageous if the polyisobutene derivatives have a low polydispersity. Polyisobutene derivatives with special (low) polydispersity are preferably obtained by using polyisobutenes which have the desired (low) polydispersity in the process according to the invention. Highly reactive polyisobutenes with low polydispersity are, for example, those with M _W / M _N of <2.5, in particular <2.0 and especially <1.5. Processes for the production of polyisobutenes with special polydispersity are known to the person skilled in the art.

The molecular weight of the polyisobutenes can be according to known metho the prior art, e.g. B. by means of gel permeation topography. Polyisobutenes, especially hochreak active polyisobutenes with defined molecular weight distributions, are commercially available, e.g. B. under the Glissopal® brands of the BASF Aktiengesellschaft, Ludwigshafen.

For use in the process according to the invention, nitrogen monoxide (NO), nitrogen dioxide (NO ₂ ), nitrous oxide trioxide (N ₂ O ₃ ), dinitrogen tetroxide (N ₂ O ₄ ), mixtures of these nitrogen oxides with one another and mixtures of these nitrogen oxides are used as the nitrogen oxide-containing oxidant with oxygen, especially NO with oxygen and NO ₂ with oxygen. Based on NMR spectroscopic investigations, it is assumed that nitrogen dioxide (NO ₂ ) acts as an active reagent. The above-mentioned substances are therefore suitable as nitrogen oxide, since from them, e.g. B. by decay, disproportionation or in the presence of Sau erstoff, NO ₂ is formed by oxidation. If oxygen is also used, it makes up 1 to 70% by volume, in particular 5 to 50% by volume, in a mixture with the nitrogen oxides. The nitrogen oxide-oxygen mixture can also inert gases, for. B. nitrogen; this is the case, for example, when using nitrogen oxide-air mixtures.

According to the invention, the amount of nitrogen oxide-containing oxidant is so chosen that the highly reactive polyisobutene and the nitrogen oxide in a molar ratio of 1: 1 to 1: 1.9, preferably 1: 1.5 to 1: 1.9 and particularly preferably uses 1: 1.7 to 1: 1.9, with Molver Ratio of the ratio of double bonds in polyisobutene Nitrogen is indicated in the oxidant containing nitrogen oxide.  

The oxidation of the polyisobutene to polyisobutene derivatives can depressurized or preferably under pressure, discontinuously or be carried out continuously.

To achieve the highest possible reaction speed and / or to achieve the most complete derivatization possible of the polyisobutenes used, it is advantageous to implement to be carried out under conditions in which the nitrogen oxide flows form.

Depending on the reaction apparatus and temperature used perature one will implement z. B. at 20 ° C at a pressure above normal pressure, d. H. ≧ 1.2 bar (absolute), at a temperature temperature of around 40 ° C at a pressure above 1.6 bar or at egg ner temperature of about 60 ° C at a pressure of 3.5 bar to lead.

The reaction is preferably carried out at a pressure in the range from 1 to 100 bar, preferably 1.1 to 20 bar and especially be preferably 2.5 to 15 bar through, for example at about 4 bar, about 5.5 bar or about 8 bar. However, this information relates to preferably on approximately ideal reaction apparatus. Kick in the reaction apparatus used due to its design Differences in pressure, e.g. B. by height differences, valves and / or measuring devices, the above pressure is in individual cases to increase the total differential pressure.

As a rule, the reaction is carried out at a temperature in the loading range from -30 to 150 ° C, preferably 10 to 100 ° C and especially preferably 25 to 80 ° C by, e.g. B. at about 35 ° C, about 50 ° C. or about 60 ° C.

Suitable measures that make it possible, regardless of the ver Reaction apparatus used the method according to the invention carry out the nitrogen oxide during the oxidation in liquid Form is present, are known to the expert and z. B. in W. Breaber, A.L. Hossma, Mathson Gasbook, 6th ed. 1980, pp. 252-309 ben. If desired, the method according to the invention can also be done at significantly higher pressure, however this is due to the necessary high pressure-resistant equipment mix not advantageous.

The reaction is advantageously carried out in an inert organic solvent. For example, aliphatic hydrocarbons such as isooctane or an n-alkane mixture (e.g. C ₁₀ -C ₁₃ ), chlorinated hydrocarbons such as methylene chloride, carbon tetrachloride or chlorobenzene, ethers such as diethyl ether, tetrahydrofuran, dioxane or are suitable for this purpose tert-butyl methyl ether, esters, such as ethyl acetate or methyl benzoate, amides, such as dimethylformamide or N-methylpyrrolidone, and acids, such as acetic acid. If the reaction products are to be used as fuel additives, one expediently works in the same solvent in which it is also added to the fuel. In general, the amounts of solvent are 30 to 90% by weight, preferably 40 to 70% by weight, of the total batch. However, it can also be operated without a solvent.

If the inventive method in the presence of a solution is carried out, the reaction product may be desired if isolated by distilling off the solvent.

A major advantage of the inventive method be is that there is usually no elaborate processing of the Polyisobutene oxidation product must be done. In particular, must usually no unreacted nitrogen oxide from the reaction product be separated. As a result of this fall in this procedure Waste water or exhaust gases containing nitrogen oxide are not present or only in below ordered quantities. The method according to the invention is therefore in considerably easier and comparatively environmentally friendly perform. It also reduces the cost of deployed nitric oxide.

Functionalized polyisobutenes which have at least one and optionally a second or third NO ₂ group which are bonded via nitrogen or oxygen can be obtained by the process according to the invention. Instead of the second or third nitro group, the functionalized polyisobutene can also have an OH group or a nitrate ester group (NO ₃ ). As a rule, in the process according to the invention, polyisobutenes with a nitroolefin structure, eg. B .:

that is, polyisobutenes with functionalized double bonds.

The content of nitrogen-containing groups (functionalization yield) in the polyisobutene derivatives obtained according to the invention is generally ≧ 65 mol%, preferably ≧ 85 mol% and in particular ≧ 90 mol% per molecule. The content of nitrogen-containing groups is particularly preferably in the range from 95 to 200 mol%, such as, for example, 95 to 175 mol% or 130 to 195 mol%. A nitrogen-containing group content of 100 mol% means that on average each molecule has a nitrogen-containing group. The content of non-functionalized olefinic double bonds in the polyisobutene derivatives obtainable according to the invention will generally not exceed ≦ 10 mol%, and is preferably ≦ 5 mol%, in particular ≦ 3 mol%, and is often below the detection limit. The content of olefinic double bonds in the polyisobutene derivatives obtainable according to the invention can advantageously be determined by means of ¹ H-NMR spectroscopy. The detection limit by means of ¹ H-NMR spectroscopy corresponds to a residual content of non-functionalized olefinic double bonds of about 1 to 2 mol%. The content of derivatives with a nitroolefin structure (functionalized double bond) is generally 5 to 20 mol%, in particular 10 to 16 mol%.

Preferred polyisobutene derivatives according to the invention are which have a nitrogen-containing group content of ≧ 95 mol%, in particular ≧ 150 mol% and a content of non-functional based olefinic double bonds of <5 mol%, in particular Have <3 mol%.

The applicant's own investigations have shown that according to functionalized obtainable by the inventive method Polyisobutenes a higher proportion of polyisobutenes with nitroo have lefin structure than that according to the method of WO 96/03367 obtained reaction products. Own investigations the applicant have also shown that functionalized Po lyisobutenes with two or more nitro groups in which usually subsequent conversion to polyisobutenamines little least lose a carbon-nitrogen structural unit, and that on the other hand the presence of nitroolefin structures in the Conversion to polyisobutenamines is not a disadvantage since the C = C double bond is also usually hydrogenated. Therefore are the reaction obtainable by the process according to the invention Products as intermediates for polyisobutenamine manufacturers more suitable, not least because of the better definition th composition of the reaction products obtained. they are therefore also the subject of the present application.

Processes for reducing polyisobutenes functionalized with nitro groups are known from the prior art or can be carried out in analogy to known processes for reducing the nitro group in nitroparaffins, as described, for. B. are described in US 4066699, GB 1,183,527 or US 3739027. In the reduction, which is usually carried out by reacting the functionalized polyisobutene mixture obtainable by the process according to the invention with hydrogen at elevated pressure and elevated temperatures in the presence of transition metal catalysts in the sense of catalytic hydrogenation, the nitrogen oxide groups become amino groups - im In the case of the NO _x groups bonded via oxygen to OH groups - reduced. Preferred transition metal catalysts include metals such as platinum, cobalt, nickel and / or palladium. For further details, reference is made to US 4066699, GB 1183527 and US 3739027, whose reaction conditions can be applied in an analogous manner to the reduction of the functionalized polyolefin mixtures obtainable by the process according to the invention. Accordingly, the present inven tion also relates to a process for the preparation of polyisobutenamines, which is characterized in that first a polyisobutene is reacted with nitrogen oxide by the processes described above and the reaction product obtained is subjected to a catalytic hydrogenation. In some cases it is advisable to subject the functionalized polyisobutene mixture obtainable by the process according to the invention to basic elimination, preferably by treatment with bases such as alkali metal hydroxides, alkali metal alcoholates and in particular alkali metal carbonates or bicarbonates. With regard to basic elimination, reference is also made to WO 96/03367.

The following examples are intended to illustrate the invention, but without restricting them.

The reactions described below were carried out in an apparatus with two tubular reactors connected in series. The first reactor had a circulation with an empty volume of 0.61 l. The post-reactor had an empty volume of 2.5 l. A first feed stream containing polyisobutene in an n-paraffin mixture (Mihagol® from Wintershall) was metered into this circulation and NO _{2 was} metered in as a second feed stream. In the case of the comparative example, the crude products obtained were freed from NO ₂ by introducing nitrogen or by applying a vacuum.

Comparative Example 1

1270 g / h of a 54% by weight solution of highly reactive polyisobutene with a number average molecular weight of 1000 and an E value of 85%, dissolved in Mihagol®, and 66 g / h of NO ₂ were circulated at atmospheric pressure Reactor 1 metered. The heating jacket temperature of both reactors was 60 ° C. The mean residence time in the reactor 1 was 0.4 h and in the reactor 2 l, 8 h. Excess NO ₂ was driven out of the solution with a stream of nitrogen at the outlet of the second reactor. The conversion of polyisobutene was 98.5%.

example 1

The reaction was carried out analogously to Comparative Example 1 under the same reaction conditions, but the ratio of polyisobutene to NO _{2 was} reduced to a stoichiometric ratio of 1: 1.9. With a total residence time in reactor 1 and 2 of 2 h in total, the conversion was 94%. Removal of NO ₂ was not necessary.

Comparative Example 2

The experimental arrangement described above was now operated at a pressure of 2.5 bar (absolute pressure). The reactor discharge was carried out via a separator in which the NO ₂ contained in the reaction mixture was removed at 200 mbar.

1500 g / h of a 50% solution of highly reactive polyisobutene with an average molecular weight of 1000 and an E value of 95, dissolved in Mihagol®, and 72 g / h of NO _{2 were} metered into the circulation of reactor 1. The total residence time in reactors 1 and 2 was 1.55 h. The polyisobutene used was completely implemented.

Example 2

Example 2 was carried out analogously to Comparative Example 2, but the NO ₂ supply was reduced to 65 g / h, which corresponds to a molar ratio of 1: 1.9. Despite the reduction in the NO ₂ feed, full sales were achieved. It was not necessary to remove the NO ₂ .

The examples and comparative examples prove that substoichiometric amounts of NO ₂ do not lead to any notable loss in sales.

Claims (10)

1. A process for the oxidation of highly reactive polyisobutene with a nitrogen oxide-containing oxidant, characterized in that the highly reactive polyisobutene and the nitrogen oxide are used in a molar ratio of 1: 1 to <1: 2. 2. The method according to claim 1, characterized in that one performs the oxidation under conditions where the Nitrogen oxide is in liquid form. 3. The method according to claim 1 or 2, characterized in that you can oxidize at a temperature in the range of Performs 10 to 100 ° C. 4. The method according to any one of the preceding claims, characterized characterized in that the oxidation at a pressure in the loading range from 1.1 to 20 bar. 5. The method according to any one of the preceding claims, characterized characterized in that the polyisobutene used a mitt leren degree of polymerization in the range of 10 to 250. 6. The method according to any one of the preceding claims, characterized characterized that you have a highly reactive polyisobutene a proportion E of highly reactive double bonds of <80% starts. 7. Functionalized polyisobutene mixture, available from a Method according to one of claims 1 to 6. 8. Process for the preparation of polyisobutenamines, thereby ge indicates that you first have a functionalized poly Isobutene mixture according to a method according to one of the claims che 1 to 6, which is a catalytic hydrogenation subjects. 9. The method according to claim 8, characterized in that one basic oxidation after oxidation with nitrogen oxide carries out reaction and the reaction product of the hydrogenation subjects.   10. Use of a functionalized polyisobutene mixture Claim 7 for the production of detergent additives for power and lubricants.