PRODUCTION OF SUBSTITUTED POLYISOBUTENES

Abstract: A process is disclosed for producing a functionalised polyisobutene (PIB) derivative, which comprises reacting a PIB with hydrogen bromide, and then reacting the resultant PIB bromide so as to displace at least one bromine atom with another functional group. Very low levels of residual halogen in the final product are achieved using this process compared with known chlorination processes, particularly if the PIB has a high percentage of vinylidene C=C bonds

Description: PRODUCTION OF SIJBSTITllTED POLYISOBUTENES The present invention relates to polyisobutenes, and in particular to hydrohalogenated and aminated polyisobutene derivatives and processes for making them, and hydrocarbon fuel compositions containing them. Hydrocarbon fuels generally contain numerous deposit-forming substances. When such fuels arc used in internal combustion cngines, deposits tend to form on and around constricted areas of the engine in contact with the fuel. For example in diesel engines, deposits are particularly prevalent in the fuel injection system, which adversely affects the performance of the engine. It is common practice to incorporate a dispersant/detergent in the fuel to inhibit formation and facilitate removal of such deposits. Particularly efficacious valve inlet port detergents are those based on polyisobutene (PIB) amines. For example PIB succinimides are well-known as lubricating oil detergents, although they have been known for use in fuels. Commercial PIBs are today of two types. So-called 'ilow-reactive" PIBs consist of largely of saturated chains or chains in which the unsaturation is nonterminal. An example is the product HYVISB, available from BP Chemicals Limited, in which 96% of the unsaturation is non-terminal. Recently a new type of "high-reactive" PIB has become available, in which a majority (about 80%) of the terminal olefinic double bonds are of the vinylidene type: -CH2-C(CH3)=CH2. Examples are ULTRAVISB, also available from BP Chemicals Limited, and GLISSOPAL, available from BASF. As their name suggests these PIBs are more reactive than conventional PIBs because of the high proportion of terminal vinylidene bonds. Preferred PIBs for use in making amine derivatives have a molecular weight in the range from 750 to 1500, with up to 40% by weight of a PIB having a molecular weight greater than 1500, for example up to 5000, typically about 2400. In a leading commercial process, PIB amines are made by chlorinating the PIB, and then aminating the resultant PIB chloride. This suffers from the disadvantage that there is always a small but significant amount of residual chlorine (from about 0.5 to as much as 3 wt%) left in the final product, which has the potential to produce traces of toxic dioxins (cyclic hydrocarbons containing oxygen and chlorine) upon combustion of fuel containing the PIB amine as additive. Chlorine is now regarded as undesirable in many products. As a result there is a need to reduce substantially or eliminate residual chlorine from PIB amines or othcr PIB derivatives made via PIB chlorides; the same would apply to bromine if used. One option to overcome this problem is to avoid the halogenation route altogether. For example EP-A-565285 discloses a process lbr the production of PIB succinimides which comprises reacting a "high-reactive" PIE with a succinic acylating agent, and then reacting the resultant product with an amine. However we have discovered that PIB derivatives such as PIB amines can be made by the halogcnation route and contain much lower levels of residual halogen than previously known, by using hydrogen bromide rather than Cl to form the PIB halide. Accordingly in a first aspect the invention provides a process for producing a polyisobutene (PIB) bromide comprising reacting a PIB with hydrogen bromide. The process for producing PIB derivatives from PIB bromides comprises first forming a PIB bromide in this way, and then reacting the bromide to displace at least one Br with another functional group. We have found that when such derivatives are made by this route rather than by the known PIB + Cl2 route, the level of residual halogen after subsequent amination or other functionalisation of the PIB bromide is of the order of ppm instead of %. Thus derivatives of PIB can be made which contain no more than 500 ppm residual bromide, and preferably no more than 1 00ppm. Levels as low as 50ppm and below can be achieved. Preferred derivatives of PIB bromides include polyisobutene amines, succinic anhydrides, succinimides, succinic acids and the esters of succinic acids, including any compounds which can function as carboxylic acylating agents. Such derivatives are well-known in the art. We have further discovered that if the PIB is specifically a "high reactive" PIB. the level of residual bromine is reduced still further. Moreover. the PIB bromide in such a case contains a substantial proportion of terminal bromine atoms, which leads to greater reactivity during subsequent functionalisation and obviously to a corresponding level of terminal functional groups, which can have potential advantages in performance of the final product. Accordingly it is preferred that at least 50%, preferably at least 70% of the terminal olefinic double bonds in the PIB are of the vinylidene type. Similarly in preferred functionalised PIB derivatives at least 50%, preferably at least 70% of the functional groups are terminal. The invention derives from the discovery that the hydrobromination of PIEs appears to differ from that of chlorination in an unexpected way. Addition of Cl2 to PIEs results in polychlorination, and aftcr further functionalisation many chlorine sites are not functionalised, leading to a high level of residual chlorine. In our experience, hydrochlorination of PIEs is extremely difficult to perform. By contrast hydrobromination occurs readily, and polybromination is virtually eliminated. It is also believed that when a "highly reactive" PIB is hydrobrominated, the hydrobromination occurs in an anti-Markownikov arrangement, i.c. the bromine adds at the less substitutcd carbon. This is the opposite of what would be expected, and indeed the opposite of what is believed to occur when "low-reactive" PIB is hydrobrominated. This is believed to be responsible for the even lower levels of residual bromine found in functionalised PIBs derived from "high-reactive" PIB. and also to the high proportion of terminal functional groups. The processes of hydrohalogenation and subsequent nucleophilic substitution are well known, and the invention does not require any special process steps. The process preferably uses hydrogen bromide but may instead use a suitable source of HBr such as an amide salt of HBr which can be made to generate HBr in situ. Solvents for the hydrobromination are not essential but are preferred: alkanes such as hexane or heptane may be used, or acetic acid. The temperature of the reaction may be between -10 and 100 C, but preferably between 10 and 60"C; room temperature is generally adequate. The reaction is generally conducted at atmospheric pressure, but if HBr gas is used this may be supplied under pressure. The reaction is suitably carried out in a vessel resistant to the corrosion effects of HBr, such as a glass-lined or stainless steel vessel. EXAMPLES EXAMPLE 1: Hydrobromination of Ultravis 10 ("High-reactive" PIB) A one litre wideneck flange tap round-bottomed flask fitted with overhead stirrer and paddle with PTFE gland, double surface condenser in reflux mode with calcium chloride drying tube, pressure equalising dropping funnel (1250ml capacity) and thermocouple/mantle/Eurotherm heating system; was charger with Ultravis 10 (1008.6g, 1 mole) and heptane (400g, solvent). The mixture was stirred until homogeneous and 30% HBr in glacial acetic acid (539g, 2 moles) added at room temperature over 2.5 hours. The temperature increased to 260C during this time. The mixture was then further heated to 450C for two hours. 1 700g water was then added to quench the reaction, and the mixture left to stand overnight. The mixture was separated into two phases: the upper cloudy phase was siphoned off and washed with 1 07g heptane in a five litre dropping funnel and the solution neutralised with 240g of a 25% solution w/w of Na,CO3 in water. The lower phase was run off and the upper phase transferred to a three litre round-bottomed flask, and the solvent removed by rotary evaporator (100 C, -685mm Hg). The resultant brown liquid was then analysed for bromine content, which was found to be 6.4%. EXAMPLE 2: Amination of Ultravis 10 hvdrobromide The same apparatus as in 1 above was used, with the exception that the addition funnel was removed, and the condenser set for distillation into a one litre round-bottomed flask. The reaction flask was charged with the Ultravis 10 hydrobromide prepared above (920.1 g, 0.85 moles), aminoethylethanolamine (834g, 8.01 moles), and xylenes (105.lg, solvent). The mixture was stirred with a nitrogen sparge and heated to 1 750C for three hours, with the condenser in reflux mode. The mixture was then cooled to 110"C, and sodium hydroxide (47% aqueous, 129g, 1.516 moles) added. Stirring was continued for a further two hours. The mixture was then left to stand overnight, following which the condenser was set up for distillation. The reaction was heated to 1900C with stirring at -685mm Hg pressure, and all solvent removed (259g collected). The reactor contents were cooled to 950C, vacuum released, and 834g of a 3:1 by weight mixture of xylene and 1 -butanol added. The mixture was stirred for 30 minutes at 850C, 378g of water added and then allowed to settle at room temperature overnight. The mixture was stirred at 800C for 30 minutes, allowed to settle, and then the clear, dark brown lower aqueous phase siphoned off. This was repeated until the pH of the aqueous phase was 8. The upper pale brown cloudy organic phase removed with 430g of 7% w/w of l-butanol in water. ?he solvent was removed from the organic phase on a rotary evaporator at 1430C, -724mm Hg. Crude yield of product was 790.9g. The product was then filtered through a 0.25 inch (6mm) Celite pad to give 715.7g of a clear golden liquid (76.2% yield). Residual bromine content was found to be less than 50ppm. EXAMPLE 3: Hydrobromination of Hvvis 10 ("Low-reactive" PIB) The same apparatus as for Example 1 was used, except that a litre wide neck flange flask was employed. It was charged with Hyvis 10 (253g, 0.253 moles) and heptane (1 00g, solvent), and the mixture stirred until homogeneous. 30% hydrobromic acid in glacial acetic acid (135g, 0.5 moles) was then added at room temperature over two hours. No exotherm was observed. The reaction was then heated to 450C and held for two hours, at which point 400ml water was added to quench the reaction followed by more heptane (loom). The reaction mixture was poured into a 2 litre separating funnel and allowed to settle out. The upper organic phase was retained and washed with lOOg of 30% aqueous sodium bicarbonate fbllowed by water (1 00g), and then dried over magnesium sulphate. The liquid was filtered off via a sinter funnel, and solvent removed on a rotary evaporator at 1000C, 724mm Hg. The yield was 215.3g of a brown, cloudy liquid. Bromine content was determined as 5.5%. EXAMPLE 4: Amination of Hyvis 10 hydrobromide The same apparatus as in 1 above was used, with the exception that the addition funnel was removed, and the condenser set for distillation into a 500ml round-bottomed flask. The reaction flask was charged with the Hyvis 1 0 bromide prepared above (1 5g, 13.9 mmol), aminoethylethanolamine (13.1 g, 125 mmol), and xylenes (105.lug, solvent). The mixture was stirred with a nitrogen sparge and heated to 1 750C for three hours, with the condenser in reflux mode. The mixture was then cooled to 1100C, and sodium hydroxide (47% aqueous, 2g, 23.5 mmol) added. Stirring was continued for a further two hours. The mixture was then left to stand overnight, following which the condenser was set up for distillation. The reaction was heated to 1 90 C with stirring at -685mm Hg pressure, and all solvent removed (259g collected). The reactor contents were cooled to 950C, vacuum released, and 140g of xylene added. The mixture was stirred for 30 minutes at 85"C, further water added and then allowed to settle at room temperature overnight. The mixture was stirred at 800C for 30 minutes, allowed to settle, and then the clear, dark brown lower aqueous phase siphoned off. This was repeated until the pH of the aqueous phase was 8. The upper pale brown cloudy organic phase removed with 5 x 1 OOml of 7% w/w of 1 -butanol in water. The solvent was removed from the organic phase on a rotary evaporator at 1430C, -724mm Hg. The product was then filtered through a 0.25 inch (6mm) Celite pad to give 6.24g of a clear golden liquid. Residual bromine content was found to be 4l0ppm. ENGINE TESTS The amines prepared in Examples 2 and 4 above were evaluated as detergency additives in fuels according to a standard engine test (M 102E), following method CEC F-05 A-93 on a Mercedes Benz M 102.982 engine. The fuel employed was (a) unleaded 95 RON Spanish commercial gasoline for Examples 5/6, and (b) a cleaner CEC fuel for Examples 7/8. The oil was RL-189/1. The amines tested were dosed in the fuel as 1 7% of a standard additive package which was added at 800ml/m3 (ppm), giving a dosage rate of the amine itself of 1 36ppm. Measurements were made of the inlet valve deposits, and the valves were also given a visual rating. In this test the lower the deposit the better, and the higher the visual rating (oul of 1 0) the better. EXAMPLE DEPOSI I S (mg) AVE. VISUAL RATING 5. Base fuel (a) alone 527 6.64 6. Ease fuel (a) + amine of Ex. 2 57 9.40 7. Base fuel (b) alone 278 7.59 8. Ease fuel (b) + amine of Ex. 4 42 9.24 These results show that PIB succinimides made according to the process of the invention are very effective at reducing valve deposits in engine.

Claims: CLAIMS: 1. Process for producing a polyisobutene (PIB) bromide, comprising reacting a PIB with hydrogen bromide. 2. Process for producing a functionalised PIB derivative, comprising reacting a PIB with hydrogen bromide, and then reacting the resultant PIB bromide so as to displace at least one bromine atom with another functional group. 3. Process according to claim 2 wherein the functionalised PIB derivative is a PIB amine, succinic anhydride or succinimide. 4. Process according to claim 2 or 3 wherein the functionalised PIB derivative has a residual bromine content of 500ppm or less, preferably 100ppm or less and more preferably 50ppm or less. 5. Process according to any preceding claim wherein at least 50% and preferably at least 70% of the functional groups in the functionalised PIR derivative or the bromine atoms in the PIB bromide are terminal. 6. Process according to any preceding claim wherein at least 50% and preferably at least 70% of the terminal olefinic double bonds in the original PIB are of the vinylidene type.

Inventors: MORETON DAVID JOHN, MORETON, DAVID, JOHN
Applicants: BP CHEMICALS ADDITIVES, MORETON DAVID JOHN, BP CHEMICALS (ADDITIVES) LIMITED, MORETON, DAVID, JOHN
Application year: 1997
Main classification: C08F8
IPC codes: C08F8