GB2149799A - Modified butene polymers - Google Patents

Abstract

The invention relates to novel butene polymers having terminal -(Ar)-CH2X groups wherein Ar is an aromatic radical and X is a halogen. They are made by (i) Friedel-Crafts polymerisation of a butene in the presence of a chain-terminater yielding a terminal aryl group, e.g. cumyl chloride, followed by (ii) halomethylation of the terminal aryl group. The resulting polymers may be reacted with organic nitrogen compounds to yield dispersant additives for fuels and lubricating oils. Examples illustrate subsequent reaction with tetraethylene pentamine, or with 2-methyl-2-oxazoline which reacts to form blocks of acetylethylene imine units, from which the acetyl groups may optionally be removed by hydrolysis.

Description

SPECIFICATION Polymer compositions This invention relates to polymer compositions comprising polyolefins having a terminal reactive halogen function. More particularly it relates to polymers and co-polymers of butenes having terminal halomethylated aromatic groups. The invention also relates to a process for the preparation of such polymers and copolymers.

Oligomers or polymers of butenes having a terminal halogen atom, in particular chlorine, are already known (US patent specification No. 3374 174). However, such products are generally unreactive and they do not permit the further reaction of nitrogen-containing compounds, such as derivatives of oxazoline, at the end of the lipid-soluble chain.

Oligomers or polymers of butenes having a terminal phenyl group are also known (Journal of Polymer Science: Polymer Chemistry Ed., Vol. 19, 2729-2735, 1981), but such substances are also inert and they do not react with nitrogen-containing compounds.

Oligomers or polymers of butenes comprising two different terminal groups, one being phenyl and other halogen have also been proposed, but these are also not sufficiently reactive to be functionalized, for example by nitrogen-containing compounds.

US Patent No. 2 938930 describes alkylaromatic compounds which are halomethylated on the aromatic ring wherein the alkyl moiety contains from 12 to 18 carbon atoms.

We have now discovered novel polymers and copolymers of butenes which, after subsequent reaction with nitrogen-containing compounds, make it possible to prepare products which have enhanced properties when used as dispersent and/or detergent additives in lubricating oils.

Thus in one aspect, the invention provides polymer compositions comprising one or more polymers or copolymers of at least one butene, which have a terminal halomethylaryl group and which have a number-average molecular weight of from 500 to 2000.

The terminal halomethylated aromatic function in the compositions of the invention provides a high degree of reactivity, in particular with respect to nitrogen-containing compounds such as oxazolines or amines. The reactivity referred to above may therefore be advantageously used to provide terminal groups on the lipid-soluble polymer which impart surface-active properties thereto.

The polymers and copolymers of butenes of the invention may conveniently be represented by the formula: [C4H8]-(Ar)-CH2X wherein Xis a halogen atom selected from chlorine, fluorine, bromine and iodine; Ar represents an at least divalent aromatic radical, preferably phenylene, on which the halomethyl group is preferably atthepara position with respect to the polybutene chain; and n is preferably an integer of from 10 to 30.

The term "butene" is used herein to include one or other of the various butenes, isobutene (isobutylene) and mixtures of the various butenes or butenes and isobutene in varying amounts.

Preferred products according to the invention are polymers of isobutene or copolymers of isobutene with at least one straight-chain butene (but-1-ene or but-2-ene).

The preferred halogen is chlorine.

In a further aspect of the invention, the polymers and copolymers of butenes having an aromatic halomethylated terminal group are generally prepared by a process comprising two stages: the preparation of a polymer of a copolymer of butene(s) comprising an aryl radical at the end of the chain; and halomethylation of the polymer or copolymer.

In the first stage, the polymer or copolymer of butene(s) terminated by an aromatic group is generally prepared by cationic polymerisation of the butene in the presence of a Friedel-Crafts acid such as boron trichloride BC13 and a transfer and initiation agent which may be any organic halide which is suitable for this type of reaction.

The polymers or copolymers having a terminal aromatic group per chain may be prepared by any suitable method, for example the method known from KENNEDY (J. Macromol. Sci. Chem. A16 (2), pages 533-542, 1981). using e.g. cumyl chloride

wherein the highly labile tertiary chlorine makes it a highly reactive agent.

The reaction mechanism of cationic polymerisation of a butene, which may be applied more particularly to the production of polyisobutene, is as follows:

The polymer which has a tertiary chlorine atom at the end of the chain is unstable; it readily undergoes dehydrochlorination under the effect of simple heating, to give two types of products:

where Ar - P I B = arylpolyisobutene.

It is considered herein, for the purposes of simplifying matters, that a product of type (Ar) - PIB is obtained, without it being necessary to specify the precise type of termination at the other end of the PIB chain.

In the second stage of the process for the preparation of the polymers or copolymers according to the invention, a halomethylation reaction is effected (for example by means of chlorodimethyl ether) or an equivalent reaction (for example using a mixture of gaseous or aqueous hydrochloric acid and formaldehyde CH2O), in the course of which a hydrogen atom is attacked, generally in the parma position of the aromatic ring.Chloromethylation is performed preferably with chloromethyl methyl ether in the presence of stannic chloride in accordance with the following reaction scheme:

The chloromethylation reaction in itself or any equivalent reaction is known (see in particular Olah, "Friedel-Crafts and related reactions", Vol.2, pages 661-687, Interscience Publishers, New York) and does not need to be particularly described in relation to the present invention. For example, the reaction temperature may be between 0 C and the boiling point of the solvent or reactants used and is preferably between 20 and 50"C. The process is preferably effected in a chlorinated solvent such as, for example, carbon tetrachloride, chloroform, methylene chloride, chlorinated esters and chlorinated ethers.The solvent generally should not be excessively polar, it is sufficient for itto have a dielectric constant which is conveniently less than 10, the maximum value thereof in fact being dependent on other parameters which may result in a different value of the dielectric constant of the solvent being used. As catalyst, it is possible to use, in the amounts which are normally employed for this type of reaction, for example, stannic chloride SnCl4, aluminium chloride AICI3, ferric chloride FeCI3, zinc chloride, titanium chloride TiCI4, boron fluoride BF3 and more generally Lewis acids such as metal halides etc.

The polymers and copolymers having a halomethylated aromatic terminal group in accordance with the invention may advantageously be used for the preparation of "ashless" lipid-soluble additives having dispersent and/or detergent properties for use in lubricating oils or in hydrocarbon fuel, such as petrols, fuel oils and gas or diesel oils.

Thus, the polymers and copolymers which contain an active halogen atom may readily react with various nitrogen-containing compounds such as oxazolines, for example 2-methyl 2-oxazoline, making it possible to produce sequenced copolymers of the poly (butene-b-acetylethyleneimine) type. Such copolymers may also be subjected to alkaline hydrolysis giving sequenced poly (butene-b-ethyleneimine) copolymers.

Moreover, the polymers and copolymers having a halomethylated aromatic terminal group in accordance with the invention may readily react with other nitrogen-containing compounds such as polyethylene polyamines, for example triethylenetetramine or tetraethylenepentamine.

The following non-limiting examples serve to illustrate the invention.

Example I Preparation of a polyisobutene terminated by a chlorobenzyl group.

a) Preparation ofcumylchloride Cumyl chloride, not being a commercial product, is prepared from 2-phenyl-propan-2-ol and hydrogen chloride, in accordance with the following reaction:

wherein + represents a phenyl radical.

The reaction is carried out at a temperature of 0 C, using dichloromethane as solvent. To generate the hydrogen chloride hydrochloric acid and sulphuric acid are used. 1 ml of 35% hydrochloric acid gives off 11 millimoles of hydrogen chloride. The hydrogen chloride is used in excess with respect to the initial alcohol (about three times more hydrogen chloride than alcohol so that the reaction is quantitative).

35% Hydrochloric acid is added dropwise to sulphuric acid stirred with a magnetic stirrer at ambient temperature. The hydrogen chloride which is given off is bubbled into a solution of 2-phenyl-propan-2-ol in dichloromethane at 0 C.

The reaction being instantaneous, complete disappearance of the OH band can be verified by infra-red spectroscopy.

The solvent is evaporated from the solution by a rotary evaporator without heating as the highly labile tertiary chlorine means that the cumyl chloride is a delicate product.

b) Preparation of an isobutene polymer having a phenyl terminal group The polymerisation reaction is carried out.under the usual conditions for cationic polymerisation in an anhydrous apparatus under a reduced pressure of approximately 0.1 mm Hg (0.1 mm Hg = 13.3 Pa).

As solvent, methyl chloride (Merck) is used. It is first dried in a column containing a molecular sieve (4 ) and then in a column filled with crushed barium oxide. The methyl chloride is liquefied in a graduated tube immersed in a container filled with ethanol and dry ice at approximately -50 C.

The isobutene used (Matheson) is dried in columns of a molecular sieve (4 A) and barium oxide. The isobutene is condensed in a graduated glass tube immersed in a container filled with liquid nitrogen. The container is then removed so as to reheat the monomer to ambient temperature.

To initiate the polymerisation reaction, boron trichloride BC13 (Merck) is used, which is kept under reduced pressure in a graduated tube.

A magnetic stirrer and the required amount of cumyl chloride are placed in a reaction vessel. The reaction vessel is placed in a bath of alcohol and dry ice in order to adjust it to the required temperature (between -10 C and -70 C).

The solvent is then slowly distilled, followed by the monomer. When those operations are concluded, the initiator BCl3 is rapidly poured in. The reaction is then left to progress for about one hour. At the end of the reaction, a few millilitres of methanol is poured into the solution in order to stop any reaction. The solvent is evaporated; the product is redissolved in a small amount of hexane and washing is effected a number of times with water to give a neutral pH-value in order to remove the boron compounds which remain. The organic phase being separated, dried on magnesium sulphate and then filtered, the solvent is evaporated. In order to purify the polymer, it may be precipitated from methanol.

The degree of polymer conversion attained under those conditions is virtually quantitative (close to 100% by weight).

In this step 5.7 g (102 millimoles) of isobutene and 0.74 g (4.8 millimoles) of cumyl chloride are used; the amount of solvent (methyl chloride) is 50 ml.

The polymer produced has a number-average molecular weight (as determined by "Gel Permeation Chromatography") of 1440, which correspond to a number n of about 26.

In a similar process, 5.4 g (96.4 millimoles) of isobutene and 1.28 g (8.3 millimoles) of cumyl chloride were used, the amount of solvent still being 50 ml. In that case, the polymer produced had a number-average molecular weight of 720, which corresponds to a number n of about 12.

c) Chloromethylation ofphenylpolyisobutene Using a reactor having three inlets, 2.9 g (i.e. about 2 millimoles) of phenylpolyisobutene having a molecular weight of 1440 is dissolved in 20 cm3 of carbon tetrachloride and 10 cm3 of chlorodimethyl ether, CICH2-O-CH3. Heating at 50"C is effected, with vigorous stirring, in order properly to dissolve the polymers A solution of 1.5 cm3 of stannic chloride SnC14 in 5 cm3 of chlorodimethyl ether is then added dropwise. The reaction is left to progress for four hours. It is noted that the solution rapidly turns black.

At the end of the reaction, the solvent is evaporated and the polymer is precipitated from an excess of methanol. The polymer is recovered, and redissolved in dichloromethane, washing with water being effected a number of times untii the solution is neutral. The organic phase is then dried over MgSO4 and then filtered. The solvent is evaporated, by heating under reduced pressure. In order to purify the polymer, it may optionally be precipitated from methanol.

Under these conditions, it is found that the chloromethylation reaction is complete and affects all the polymeric chains.

The number-average molecular weight of the product obtained is about 1500.

Example 2 The degree of reactivity of polyisobutene having a terminal benzyl chloride type group, which is produced in Example 1 c, makes it possible to attach other groups for example nitrogen-containing groups. This is illustrated by the reaction with 2-methyl 2-oxazoline, which is carried out in accordance with the following scheme and which resuits in the formation of a sequenced poly-(isobutene-b-acetylethyleneimine) copolymer:

wherein + represents a phenylene radical and m denotes the degree of polmerisation of 2-methyl-2oxazoline.

Using a reaction vessel having three inlets and provided with a stirring system, a refrigerant, a dropping funnel and a thermostat probe, a solution of 20.25 g (13.5 millimoles) of polyisobutene having a benzyl chloride terminal grouping as produced in Example 1 c, in 250 ml of benzonitrile and then 2.24 g (13.5 millimoles) of finely crushed potassium iodide are successively introduced into the reaction vessel. The mixture is put under a nitrogen atmosphere and stirred at ambient temperature. Using the dropping funnel, 29.75 g (350 millimoles) of 2-methyl 2-oxazoline is added and the mixture is vigorously stirred and heated at a temperature of 105"C for 20 hours. Complete disappearance of oxazoline monomer is monitored by means of infra-red spectrometry.

The reaction mixture is then filtered to separate the potassium salts and the filtrate is poured into an excess of petroleum ether in order to precipitate the copolymer. It is then purified by redissolution in methylene chloride and re-precipitation from petroleum ether. It is finally dried to a constant weight, under reduced pressure.

The 13C NMR spectrum of the product in solution in deuterochloroform is characteristic of isobutene units:

Ol 59.5 ppm (with respect to TMS) (2) 38.2 ppm O3 31.2ppm and acetylethyleneimine

O ppm (ss) 43.8 - 47.0 ppm 171.3ppm Example 3 Example 2 is repeated but 5.95 g (70 millimoles) of 2-methyl 2-oxazoline is used instead of 29.75 g (350 millimoles), to produce a sequenced poly(isobutene-b-acetylethyleneimine) copolymer having a nitrogen content of 3.4% by weight.

Example 4 The product obtained from Example 3 is subjected to hydrolysis in the presence of sodium hydroxide, and a sequenced poly(isobutene-b-ethyleneimine)copolymer is obtained, having a nitrogen content of 3.7% by weight.

Example 5 (comparative) Example 2 is repeated but the polyisobutene having a terminal benzyl chloride type group according to the invention, is replaced by an equivalent amount of polyisobutene having the same molecular weight, with a phenyl terminal group, PlB-().

The product obtained after 20 hours reaction is partially soluble in methylene chloride and in water. The 13C NMR spectrum of the product fraction soluble in methylene chloride is similar to that of the initial polyisobutene while the 13C N MR spectrum of the fraction of product which is water-soluble is characteristic of a polyacetylethyleneimine. It appears therefore that a mixture of two homopolymers are obtained and that no reaction of the 2-methyl 2-oxazoline on the phenyl terminal group of the polyisobutene takes place.

Example 6 (comparative) Example 2 is repeated but the polyisobutene having a terminal benzyl chloride type group according to the invention, is replaced by an equivalent amount of polyisobutene of the same molecular weight, with a chlorine termination, PIB-CI.

In the heating operation, it is observed that hydrogen chloride is given off when the temperature is higher than 50"C, this being due to decomposition of the PIB-CI.

The solubility of the product obtained after 20 hours reaction and the 13C NMR spectra of the two fractions are similar to those found in Example 5, the only difference being the appearance of signals which are characteristic of unsaturated double bonds in the fraction which is soluble in methylene chloride. Those observations indicate that there has not been any reaction of the 2-methyl 2-oxazoline with the chlorine termination of the polyisobutene and that the latter has decomposed to give rise to a terminal olefinic type group.

Example 7 (comparative) Example 2 is repeated but the polyisobutene having a terminal benzyl chloride type group according to the invention, is replaced by an equivalent amount of polyisobutene having the same molecular weight, with phenyl and chlorine terminal groups ()-PIB-CI.

The observations made are identical to those set out in Examples 5 and 6, thus confirming the absence of any reaction of the 2-methyl-2-oxazoline with the phenyl and chlorine terminal groups.

Example 8 2 g (10.6 millimoles) oftetraethylenepentamine is added to 15 g of the product obtained in Example 1c (that is to say, about 10 millimoles), in solution with 100 ml of xylene. The resulting reaction mixture is stirred for 5 hours under reflux of the xylene.

The product obtained, which is isolated by precipitation from methanol and dried, contains 4.1% by weight of nitrogen.

Example 9 The dispersentcapability of the products obtained in Examples 2 to 8 was determined in accordance with the spot method described by GATES V.A. et al in SAE Preprint No. 572 (1955) or SCHILLING A. in "Les huiles pour moteurs et le graissage des moteurs" (Oils for engines and greasing engines) Edit. TECHNIP, Volume 1, page 89 (1962). That method involves establishing the ratio between the diameters, after 24 hours, of two concentric spots formed by depositing a drop of hydrocarbon oil containing 2% by weight of polymer and 1% by weight of carbonaceous deposits (sludge) on a sheet of filter paper.

The measurements are made at 20"C (A), at 200"C (B) and after cooling to 20"C (C). The degree of dispersivity of the product increases in proportion to the ratio between the diameters of the spots approaching unity. As indicated by the results set out in the following table, polyisobutene with a terminal benzyl chloride type group according to the invention, after reaction with a nitrogen-containing compound such as 2-methyl 2-oxazoline, possibly after hydrolysis, has good dispersion properties. That is also the case with polyisobutene having a benzyl chloride terminal group after reaction with tetraethylenepentamine.

Fraction soluble Dispersent capability in hydrocarbon phase ofexample rAJ (B) (C) 2 0.81 0.76 0.79 3 0.81 0.77 0.79 4 0.81 0.78 0.80 5 0.12 0.14 0.11 6 0.10 0.11 0.10 7 0.12 0.12 0.11 8 0.81 0.80 0.81

Claims (16)

1. A polymeric composition comprising one or more polymers or copolymers of at least one butene, having a terminal - AR - CH2X group, (wherein Ar represents an at least divalent aromatic radical and X is a halogen atom selected from chlorine fluorine, bromine and iodine), and having a number-average molecular weight of 500 to 2000.

2. A composition according to claim 1 wherein the butene is isobutene.

3. A composition according to either of claims 1 and 2 wherein said polymer or said copolymer corresponds to the following formula: (C4H8)n - Ar - CH2 - X wherein Ar and X are as defined in claim 1 and n is in an integer wherein from 10 to 30.

4. A composition according to any one of the preceding claims wherein the group -CH2X is in the para position of the aromatic radical relative to the polymeric chain.

5. A composition according to any one of the preceding-claims wherein the halogen is chlorine.

6. A process for the preparation of polymeric composition according to any one of the preceding claims which comprises a) preparing a polymer or a copolymer or butene(s) having a terminal aryl radical; and b) halomethylation of said polymer or copolymer.

7. Use of a polymeric composition according to one of claims 1 to 5 in the preparation of dispersent or detergent additives for lubricating oils, hydrocarbon fuels and/or motor fuels, wherein said polymeric composition is reacted with at least one nitrogen-containing compound.

8. Use according to claim 7 wherein the nitrogen-containing compound is 2-methyl 2-oxazoline, the product obtained being a sequenced poly(butene-b-acetylethyleneimine) copolymer.

9. Use according to claim 7 wherein the nitrogen-containing compound is triethylenetetramine or tetraethylenepentamine.

10. A dispersant or detergent additive for lubricating oils, hydrocarbon fuels and/or motor fuels prepared by reacting at least one composition according to any one of claims 1 to 5 with at least one nitrogen-containing compound.

11. A composition according to any one of claims 1 to 5 substantially as herein described.

12. A composition according to any one of claims 1 to 5 substantially as herein described in any one of Examples 1-4,8 and 9.

13. A process according to claim 6 substantially as herein described.

14. Use according to claim 7 substantially as herein described.

15. A detergent or dispersant additive according to claim 10 substantially as herein described.

16. Each and every novel product compound, composition, method, process and use substantially as herein described.