GB1587272A - Manufacture of tertiary aliphatic ethers - Google Patents

Description

(54) MANUFACTURE OF TERTIARY ALIPHATIC ETHERS (71) We, BASF AKTIENGESELLSCHAFT, a German Joint Stock Company of 6700 Ludwigshafen, Federal Republic of Germany, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a process for the manufacture of a tertiary alkyl aliphatic ether by continuous reaction of an alcohol with an isoolefin in the presence of a cation exchanger.

Houben-Weyl, Methoden der Organischen Chemie, volume 1/1, pages 585587, discloses that cation exchangers, including sulfonated resins, may be used as catalysts in continuous processes. It points out that the particle size of the resin has a substantial influence on its catalytic activity. Hence, following the disclosure in Houben-Weyl, particles with a diameter of from 0.5 to 1 mm are chosen for batchwise catalytic reactions. On the other hand, continuous processes in industrial columns require a particularly coarse material in order to allow the free passage of the reactants. Correspondingly, U.S. Patent 2,802,884 also teaches that the continuous alkylation of phenol with alkenes should only be carried out with coarse sulfonic acid resin exchangers of from 10 to 20 mesh; the catalyst forms a fixed bed in the reactor.

U.S.'Patent 3,037,052 discloses a reaction of carboxylic acids with olefins in the presence of cation exchangers containing sulfonic acid groups. It teaches that the catalytic activity of the conventional cation exchangers is less than that of many conventionally used homogeneous catalysts, for example strongly acid catalysts, e.g. sulfuric acid or phosphoric acid, and that elevated temperatures and lengthy reaction times are frequently needed to accelerate the reaction. In the prior art processes, the yield of ester is from about 17 to 40 percent if the reaction is carried out with aliphatic monocarboxylic acids and the conventional gel-like cation exchangers. As shown by the above patent, it is more advantageous to carry out the reaction with macro-reticular exchangers than with acids and the conventional gellike cation exchangers as catalysts, because the catalyst can easily be separated off and re-used, colored by-products are not formed, corrosion of parts of the equipment is avoided and unconverted carboxylic acid can readily be separated from the catalyst without diluting the acid and be reused without additional purification. The patent points out that these advantages, and good yields, are only achieved if the cation exchanger has a macro-reticular structure, i.e. a particularly porous (macroporous) structure and accordingly does not have a gel-like structure.

The manufacture of such macro-reticular exchangers by copolymerization of ethylene-like monomers with polyvinylidene monomers in the presence of special catalysts, e.g. of alkanols, is described. Regarding the macro-reticular or gel-like structure of resins, reference may be made to German Patent 1,168,908.

Ion Exchange in the Process Industries (Soc. of Chem. Ind., 1970, London), pages 52-53, teaches that pulverulent exchanger resins can be used as catalysts in batchwise operation only, and that the catalyst must be discarded after each batch and can no longer be regenerated, since such catalysts can be isolated by filtration with great difficulty only and with uneconomically long filtration times, or are so fine that they pass through filters. A coarser particle size is therefore recommended if the exchanger is to be used as a catalyst.

U.S. Patent 2,480,940 discloses that isobutylene can be reacted with an aliphatic alcohol in the presence of hydrogen ion exchangers at from 66 to 1500C and under a pressure of from 2 to 34 bars to give alkyl tert.-butyl ethers. Suitable catalysts are phenolic resins, carboxylic acid resins and sulfonic acid resigns. As is shown by the description and in particular by the Examples (column 3, lines 2851, Table), only coarse exchangers, which for continuous operation are arranged as a fixed bed, are used.

U.S. Patent 3,482,952 describes a similar reaction; here again, sulfonic acid resins may be used as exchangers. Only coarse exchanger resins can be employed for continuous operation; resins of from 10 to 50 mesh (about 2-0.3 millimeters), or even coarser, are advantageous. For continuous operation, the catalyst is arranged as a fixed bed (column 4, lines 2-42).

German Laid-Open Application DOS 2,445,774 describes a reaction using a macro-reticular, sulfonated ion exchange catalyst at from 26.7 to 93.30C. It teaches, with regard to U.S. Patent 2,480,940, that only macro-reticular exchangers, but not gel-like exchangers, are suitable for the industrial manufacture of tertiary alkyl ethers, particularly at relatively low temperatures. Macro-reticular resins in particular means resins which have a relatively fixed macro-geometry, have an inner porosity and essentially do not swell whilst the process is carried out; macro-reticular resins have an effective surface area, in the dry state, of more than 20 m2/g and in general of more than 40 m2/g, whilst gel-like resins have a surface area of less than 5 m2/g and in general less than 2 m2/g (cf. the description on page 4). As shown by the Examples, the catalysts are arranged as a fixed bed if the process is carried out continuously. High catalyst factors, e.g. of from 0.2 to 10, the factor being defined as dry catalyst (g) feed rate (g of isoolefin/hour) are necessary. This high catalyst usage is accompanied by correspondingly high losses due to chemical consumption and mechanical wear.

All these processes are unsatisfactory in respect of yield, simplicity and economy of operation, and, in particular, removal of the large amount of heat of reaction.

We have found that a tertiary aliphatic ether of the formula

where R', R2, R3 and R4 are identical or different and each is an aliphatic radical, and R' and R4 may also be hydrogen, can be manufactured continuously in an advantageous manner by reaction of an alcohol with an isoolefin in the presence of a cation exchanger, if an isoolefin of the formula

where R2 and R3 have the above meanings, is reacted continuously with an aliphatic alcohol of the formula

where R', and R4 have the above meanings, in the presence as catalyst of an organic cation exchaiiger containing sulfonic acid groups and having a particle size of from 10 to 200 micrometers, the exchanger being suspended in the liquid reaction mixture.

Further, we have found that the reaction may be carried out particularly advantageously if the reaction mixture is mixed by stirring at not less than 100 revolutions per minute or by introducing a shearing energy corresponding to this speed of stirring.

If isobutylene and ethanol are used, the reaction may be represented by the equation:

Compared to the conventional processes, the process of the invention is surprisingly able to give a large number of tertiary alkyl ethers more simply and more economically, and with better space-time yield and greater purity, particularly on an industrial scale and in continuous operation. The heat of reaction is removed more effectively and special cooling equipment is unnecessary.

Instead, conventional reactor jacket cooling or pipe coil cooling suffices. Since lower reaction temperatures can be used, the life of the catalyst is higher, and hence the process is more economical. Compared to the disclosures of the cited publications, the process of the invention permits the use of lower and hence substantially more advantageous catalyst factors. The catalyst factor is defined as dry catalyst (g) feed rate (g of starting material lI/hour) The reaction itself takes place more rapidly, particularly at below 120"C. The catalyst consumption, based on amount of end product, is less than in the more expensive more conventional fixed bed processes. All these advantages of the process of the invention are surprising, especially because it is not primarily macroreticular exchanger resins which are used but gel-like exchanger resins are advantageously employed. Using fine, pulverulent exchange resins in the process according to the invention in continuous operation, poorer yields, a lower throughput of the reaction mixtures and correspondingly inadequate removal of the heat of reaction, resulting in polymerization reactions, would have been expected, in view of the disclosures in Houben-Weyl. It is also surprising that the catalyst can be suspended in the flowing reaction mixture without forming impermeable layers, but can be retained on the reactor filter unit and be mixed back in again or be separated off without the addition of filtration adjuvants.

Furthermore, it was unexpected that even cheap exchangers of the gel type could be used at relatively low reaction temperatures without disadvantages such as a lower space-time yield, greater expense in recycling unconverted starting materials, reduction in selectivity and increase in side-reactions, e.g. olefin oligomerization, condensation of the alcohol to give the dialkyl ether, possible etherification of linear olefins and labile behaviour of the catalyst. Disadvantages of continuous fixed bed processes, e.g. high temperature gradients corresponding to the concentration gradient of the starting materials in the reactor and irreversible oligomerization of the isoolefins, especially at high concentration, are avoided.

The invention is based, inter alia, on the observation that catalyst particles of from 10 to 200 micrometers in size can be suspended, by means of a stirrer or mixer, in the continuously flowing reaction mixture so that they are retained on a filter unit of the reactor without forming an impermeable membrane, and are mixed back in again. It does not require any specific type of filter to achieve this.

Accordingly, the losses of catalyst particles are very low. Surprisingly, very long operating times can be achieved with the process of the invention. Breakdowns due to film formation on the filters only occur if the mixer fails and can, where necessary, be dealt with by introducing an inert gas in counter-current or by pumping back part of the reaction mixture.

The starting material II can be reacted with the alcohol III in the stoichiometric amount, in a less than stoichiometric amount or in excess, preferably in a ratio of from 0.1 to 10, advantageously from 0.25 to 4, and especially from 0.5 to 2, moles of starting material II per mole of starting material Ill.

Preferred starting materials II and III, and accordingly, preferred end products 1, are those where Rl, R2, R3 and R4 are identical or different and each is alkyl of 1 to 26, especially I to 7, carbon atoms, the carbon chain of which may be interrupted by 1, 2 or 3 oxygens, and R1 and R4 may also be hydrogen. The above radicals may in addition be substituted by one or more groups and/or atoms which are inert under the reaction conditions, e.g. chlorine, bromine or alkyl or alkoxy each of I to' 3 carbon atoms.

The starting materials Ill are preferably primary alcohols, i.e. R4 is a hydrogen atom. Preferably, R' and R4 do not carry a hydroxyl group, although they may also possess one or more further hydroxyl groups, advantageously 3 or 2 or especially one; accordingly, poly-, tetra-, tri- or di-tert.-alkyl ethers are formed in the reaction. Examples of starting materials Ill with more than one hydroxyl group are those having the formula lHOH2ClnR5 lila and accordingly the end products from them would have the formula

where R2 and R3 have the above meanings especially the preferred meanings, R5 is a tetravalent, trivalent or, in particular, divalent alkylene of I to 20, especially I to 7, carbon atoms, the carbon chain of which may in addition be interrupted by 1,2 or 3 oxygens, and n is 4, 3 or especially 2, and in addition, when n is 2, R5 may also be merely a single bond between the 2 carbon atoms of the 2

groups or the

groups. The above radicals may in addition be substituted by one or more groups and/or atoms which are inert under the reaction conditions, e.g. chlorine, bromine or alkyl or alkoxy each of 1 to 3 carbon atoms.

In particular, mixtures of alcohols III, advantageously those referred to as fatty alcohols, may be used for the process of the invention. Fatty alcohols and fatty alcohol mixtures are obtained on a large scale by hydrogenation of natural fats and oils, or by reduction of synthetic paraffincarboxylic acids and their esters, by oxidation of paraffins or by hydrolysis of esters such as sperm oil. The fatty alcohol mixtures obtained from the oxo synthesis, followed by a reduction, and corresponding mixtures of high alcohols obtained by synthesis from carbon monoxide and hydrogen, e.g. by the synthol process, or by the Alfol (Registered Trade Mark) process, may also be used. Regarding the definition of fatty alcohols and the manufacture of starting materials III, reference may be made to Ullmanns Encyklop die der technischen Chemie, volume 7, pages 437 et seq., volume 13, pages 60 et seq., volume 3, pages 289 et seq., and Supplementary Volume, pages 86 et seq. In contrast to the conventional processes, mixtures of isoalkenes Il and of isoalkenes Il with linear olefins, e.g. butadiene or n-but-l-ene, or linear alkynes, e.g. n-but-l-yne, or alkanes, may also advantageously be used; such mixtures are formed, for example, on cracking or dehydrogenating hydrocarbons, e.g.

petroleum, or oligomerizing olefins, especially isobutylene, propylene or n-butene, or hydrogenating carbon monoxide.

The following are exampies of isoolefins which may be used as starting materials ll: 2 - methyl - n - pent - 1 - ene, 2 - methyl - n - hex - 1 - ene, 2 methyl - n - hept - I - ene, 2 - methyl - n - oct - I - ene, 2 - methyl - n - non I - ene, 2 - methyl - n - dec - 1 - ene, 2 - methyl - n - undec - I - ene, 2 - methyl - n - dodec - 1 - ene, 2 - methyl - n - tridec - I - ene, 2 - methyl - n tetradec - I - ene, 2 - methyl - n - pentadec - 1 - ene, 2 - methyl - n - hexadec I - ene, 2 - methyl - n - heptadec - 1 - ene, 2 - methyl - n - octadec - I - ene, 2 - methyl - n - nonadec - 1 - ene, 2 - methyl - n - eicosene, 2 - methyl - prop 1 - ene and 2 - methyl - n - but - 1 - ene, the above alkenes which are substituted by ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec.-butyl or tert.-butyl instead of methyl in the 2-position, and the above alkenes which are additionally substituted by methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec.-butyl or tert.-butyl in the 3-position and/or 4-position.

The following are preferred: isobutylene 2,3 - dimethyl - but - I - ene, 2 methyl - but - I - ene, 2 - methyl - oct - 1 - ene, 2 - methyl - pent - 1 - ene, 2 methyl - hex - I - ene, 2 - methyl - hept - 1 - ene, 2,3 - dimethyl - pent - 1 ene, 2,3 - dimethyl - hex - 1 - ene and 2,4,4 - trimethyl - pent - I - ene.

The following are examples of alcohols which may be used as starting materials Ill: methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, tridecyl alcohol, tetradecyl alcohol, pentadecyl alcohol, cetyl alcohol, margarine alcohol (heptadecyl alcohol), stearyl alcohol, nonadecyl alcohol, arachyl alcohol, heneicosyl alcohol, behenyl alcohol, tetracosanyl alcohol, hexacosanyl alcohol, 2-ethylhexanol and 2-methyl-7-ethyl-4undecanol; isobutyl alcohol, isoamyl alcohol, isohexyl alcohol, isoheptyl alcohol, isooctyl alcohol, isononyl alcohol, isodecyl alcohol, isoundecyl alcohol, isododecyl alcohol, isotridecyl alcohol, isotetradecyl alcohol, isopentadecyl alcohol, isohexadecyl alcohol, isoheptadecyl alcohol and isooctadecyl alcohol; ethylene glycol monoethers and propylene glycol monoethers which are obtained by reacting the above fatty alcohols of 10 to 20 carbon atoms with 2, 3, 4 or 5 moles of ethylene oxide or propylene oxide per mole of alcohol, and corresponding glycol monoethers of the above fatty alcohols obtained by simultaneous reaction with ethylene oxide and propylene oxide in the above molar ratios; ethylene glycol, 1,2 - propyleneglycol, 1,3 - propylene glycol, neopentylglycol, 1,2 - butylene glycol, 1,3 - butylene glycol, 1,4 - butylene glycol, 2,3 - butylene glycol, 1,5 pentylene glycol, 2,4 - pentylene glycol, 1,6 - hexylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, methylethylene glycol, ethylethylene glycol, n-propylethylene glycol, isopropylethylene glycol, n-butylethylene glycol, isobutylethylene glycol, sec.-butylethylene glycol, tert.-butylethylene glycol, methyl-l,2-propylene glycol, ethyl-l,2-propylene glycol, n - propyl - 1,2 propylene glycol, isopropyl - 1,2 - propylene glycol, n - butyl - 1,2 - propylene glycol, isobutyl - 1,2 - propylene glycol, sec. - butyl - 1,2 - propylene glycol, tert. - butyl - 1,2 - propylene glycol, methyl - 1,3 - propylene glycol, ethyl - 1,3 propylene glycol, n - propyl - 1,3 - propylene glycol, isopropyl - 1,3 - propylene glycol, n - butyl - 1,3 - propylene glycol, isobutyl - 1,3 - propylene glycol, sec. butyl - 1,3 - propylene glycol, tert. - butyl - 1,3 - propylene glycol, methyldiethylene glycol, ethyldiethylene glycol, n - propyldiethylene glycol, isopropyldiethylene glycol, n - butyldiethylene glycol, isobutyldiethylene glycol, sec. - butyldiethylene glycol and tert. - butyldiethylene glycol.

The reaction is in general carried out continuously at from 30 to 1500C, preferably from 40 to 1300C and especially from 50 to 1200C, under reduced pressure, superatmospheric pressure or atmospheric pressure, advantageously under a pressure of from 1 to 100 bars, preferably from 1 to 50 bars. The mean residence time is advantageously from 0.05 to 2 hours, especially from 0. I to I hour and the throughput is preferably from I to 120, especially from 5 to 50, kilograms of starting material II per kilogram of catalyst per hour.

The catalysts used are organic cation exchangers containing sulfonic acid groups, advantageously resins consisting of a sulfonated styrene-divinylbenzene copolymer or other sulfonated crosslinked styrene polymer, or a phenolformaldehyde or benzene-formaldehyde resin containing sulfonic acid groups. The use of sulfonated styrene-divinylbenzene copolymer exchangers is preferred. The exchangers are in the acid form, not in the form of a salt. The catalyst particle size is from 10 to 200, preferably from 20 to 180, especially from 25 to 150, micrometers.

Advantageously, the catalyst has a gel-like structure. Examples of suitable catalysts are exchanger resins commercially available under the name Lewasorb A-10. It is also possible to mill other commercial resins, e.g. Amberlite IR-120, Dowex 50, Lewatit S-100, Nalcite HCR, Permutit RS and Wofatit KPS-200, to the particle size according to the invention, and use them in this form. (Lewasorb, Amberlite, Dowex, Lewatit, Nalcite, Permutit and Wofatit are Registered Trade Marks).

Advantageously, they are dehydrated by conventional methods, e.g. by heating at from 100 to 1100C under reduced pressure, before being used. However, they can also be dehydrated by removing the water with a hydrophilic organic liquid and then heating the material at 1000C under reduced pressure, or by azeotropic distillation with an organic liquid.

During the reaction, the catalyst is in suspension, as a rule in the reaction mixture which is being formed. Advantageously, a part of the liquid starting material Ill or of the starting mixture of Ill and olefin II is taken and the catalyst is suspended therein, with thorough mixing. Advantageously. no additional solvent is used, but at times, for example in order to lower the viscosity of the reaction mixture, solvents which are inert under the reaction conditions may be employed.

Examples of suitable solvents are aliphatic or cycloaliphatic hydrocarbons. e.g.

heptane, nonane, gasoline fractions with a boiling range of from 70 to l900C, cyclohexane, methylcyclohexane, decal in, petroleum ether, hexane, naphtha, 2,2,4-trimethylpentane, 2,2.3-trimethylpentane, 2,3,3-trimethylpentane and octane, halohydrocarbons, especially chlorohydrocarbons, e.g. tetrachlorocthylene.

1,1,2,2-tetrachloroethane, 1,1,1,2-tetrachloroethane, dichloropropane, methylene chloride, dichlorobutane, chloroform, carbon tetrachloride. tetrachloroethane, 1,1, 1-trichloroethane, 1,1 ,2-trichloroethane, trichloroethylene, pentachloroethane, cis-dichloroethylene, 1,2-dichloroethane and l,l-dichloroethane, tetrahydrofuran, dioxane, and mixtures of the above. Advantageously, the amount of solvent is from 10 to 1,000 percent by weight, preferably from 50 to 100 percent by weight. based on starting material II. In the case of mixtures of starting materials ll, e.g. from the cracking of petroleum, the saturated hydrocarbons contained in the mixture may serve as solvents for the suspension. The amount of initially taken starting material III or starting mixture and/or organic solvent is suitably such that from I to 40, preferably from 3 to 25, especially from 5 to 15, percent by weight of the catalyst, based on the weight of total liquid mixture in the reaction space, is suspended in the reaction mixture which is being formed.

Advantageously, the reaction mixture is subjected to mixing throughout the reaction, preferably by stirring at not less than 100, advantageously from 200 to 2,000, especially from 300 to 1,000, revolutions per minute. If mixing devices without a stirrer are used, including, for example, mixing by means of an inert gas such as nitrogen, those which introduce into the mixture an amount of shearing energy corresponding to the above speed of stirring, are preferred. In this way, a fine suspension is obtained. Provided the above mixing conditions are employed, a broad range of conventional stirring equipment may be used, namely injectors, ball nozzles, vortex nozzles, turbine stirrers, mixing nozzles, Lechler mixing nozzles, paddle stirrers, anchor stirrers, bar-type stirrers, propeller stirrers. Cramer stirrers, vibro-mixers, finger-type stirrers, crossbeam stirrers, gyratory stirrers, grid stirrers, flat stirrers, spiral turbines, scoop stirrers, planetary stirrers, centrifugal gyratory stirrers, rotating atomizers, ejectors, triangular stirrers, hollow stirrers, tubular stirrers and impeller stirrers. It is also possible to use equipment and installations such as stirred kettles, stirred kettle cascades, flow tubes, air-lift type stirring units.

homogenizing equipment, gyratory mixers, turbo-mixers, emulsifying centrifuges, ultrasonic tubes, flow mixers, rotating drums, chamber reactors, circulatory reactors, loop reactors, cellular reactors, screw reactors, bubble columns, jet scrubbers, liquid ring pumps, ejector-type reactors and thin film reactors; stirred kettles are preferred if only for economic reasons.

The reaction may be carried out as follows: a liquid mixture of starting materials II and III, with or without solvent, is passed, at the reaction temperature and the reaction pressure, through a suspension of the catalyst, in the starting mixture or reaction mixture and is filtered. The end product is then isolated from the reaction mixture in the conventional manner, e.g. by distillation. Filtration is advantageously carried out before the suspension leaves the reactor. Suitable filters are acid-resistant filter cloths, wire mesh filters and sintered metal filters, provided the mesh width or pore diameter is less than the size of the catalyst particles.

Unreacted starting materials are advantageously recycled after removing the end product, or are passed to the next stage in the case of a multi-stage installation. An advantageous embodiment of the etherification of isobutylene (which may be in the form of a mixture, e.g. with up to equimolar amounts of n-butenes, as obtained, for example, in the extraction of 1,3 - butadiene from C4-fractions) with methanol is, for example, to carry out the reaction in a two-stage cascade.

The tert.-alkyl ethers I which may be manufactured by the process of the invention are solvents, anti-knock compounds, fuel additives and valuable starting materials for the manufacture of anti-knock compounds, fuel additives, dyes, pesticides, drugs, emulsifiers, dispersing agents, stabilizers, antioxidants, plasticizers, corrosion inhibitors, disinfectants, seed dressings, anti-aging compounds, crop protection agents and scents. Methyl tert.-butyl ether is an excellent anti-knock compound, especially in fuels which contain little or no lead.

Regarding the use, reference may be made to the above publications and to Oil and Gas Journal, June 16, 1975, pages 50 52, and Ullmanns, Encyklop die der technischen Chemie, volume 3, page 107.

In the Examples which follow, parts are by weight, and bear the same relation to parts by volume as that of the kilogram to the liter.

EXAMPLE 1 A suspension of 25 parts of methanol and 25 parts of exchanger resin is prepared in a stirred reactor, by stirring at 500 revolutions per minute at 800C under 2 bars, and 45 parts of isobutylene are passed in. The exchanger resin is a sulfonated styrene-divinyl-benzene copolymer resin which has been dehydrated, before use, by heating for 20 hours at 100cm under reduced pressure; it has a gel structure and 2 particle size of from 20 to 150 micrometers. After introduction of the isobutylene the suspension in the reactor is stirred steadily at 500 revolutions per minute. After 20 minutes, 138 parts/hour of methanol and 240 parts/hour of isobutylene are passed in at 80"C and 11.5 parts and correspondingly 378 parts of suspension are filtered through a suction line fitted with a metal filter (pore diameter 10 micrometers) and passed to a fractional distillation. After 200 hours' operation, 36,000 parts of methyl tert.-butyl ether (representing a virtually quantitative yield), of boiling point 55"C/1,013 millibars, are obtained in addition to 690 parts of methanol and 690 parts of isobutylene. The conversion is 95 of theory, based on methanol used, and 98.5 of theory, based on isobutylene used.

EXAMPLE 2 A distillate from the cracking of petroleum oil is used; the distillate has a boiling point -60CA bar and is composed of 46.2 percent by weight of isobutylene, 27.2 percent by weight of n-but-l-ene, 9.8 percent by weight of trans-but-2-ene, 6.8 percent by weight of cis-but-2-ene, 8.2 percent by weight of n-butane and 1.8 percent by weight of iso-butane. A suspension of 10 parts of methanol, 50 parts of petroleum cracking distillate and 25 parts of exchanger resin is prepared in a stirred reactor by stirring at 500 revolutions per minute at 1000C and 14 bars. The exchanger resin is a sulfonated styrene-divinylbenzene copolymer resin which has been dehydrated before use by heating for 20 hours at 100do under reduced pressure; it has a gel structure and a particle size of, from 20 to 150 micrometers.

The suspension in the reactor is then stirred steadily at 500 revolutions per minute.

After 20 minutes, 162 parts/hour of methanol and 596 parts/hour of petroleum cracking distillate are introduced at 1000C and 14 bars and corresponding 758 parts of suspension are filtered through a suction line fitted with a metal filter (pore diameter 10 micrometers) and are passed to a fractional distillation. After 100 hours' operation, 34,500 parts of methyl tert.-butyl ether (99% of theory, based on reacted starting material II) of boiling point 550C/1,013 millibars are obtained. The conversion is 77.4, based on starting material III employed and 79%, based on starting material II employed.

EXAMPLE 3 A petroleum cracking distillate, having the composition described in Example 2, is used. A suspension of by weight of n-but-l-ene, 16.6 percent by weight of trans-but-2-ene, 11.5 percent by weight of cis-but-2-ene, 13.9 percent by weight of n-butane and 3.1 percent by weight of iso-butane. A suspension of 10 parts of methanol, 50 parts of the above distillate and 25 parts of exchanger resin is prepared in a stirred reactor by stirring at 500 revolutions per minute at 800C and 12.5 bars. The exchanger resin is a sulfonated styrene-divinylbenzene copolymer resin which has been dehydrated before use by heating for 20 hours at 1000C under reduced pressure; it has a gel structure and a particle size of from 20 to 150 micrometers. The suspension in the reactor is then stirred steadily at 500 revolutions per minute. After 20 minutes. 9.3 parts/hour of methanol and 126.7 parts/hour of petroleum cracking distillate are introduced at 80"C and 12.5 bars and correspondingly 136 parts of suspension are filtered through a suction line fitted with a metal filter (pore diameter 10 micrometers) and are passed to a fractional distillation. After 100 hours' operation, 1,070 parts of methyl tert.-butyl ether (99 /" of theory, based on reacted starting material II) of boiling point 55 C/l,013 millibars are obtained. The conversion is 66, based on starting material Ill employed, and 91%, based on starting material 11 employed. In addition, 110 parts of isobutylene and 310 parts of methanol are obtained.

EXAMPLE 5 (The numbers relate to the drawing) A suspension of 290 parts of methanol, 806 parts of a petroleum cracking distillate having the composition described in Example 2 and 220 parts of exchanger resin is prepared in a stirred reactor (I) by stirring at 500 revolutions per minute at 800C and II bars. The exchanger resin is a sulfonated styrenedivinylbenzene copolymer resin which has been dehydrated before use by heating for 20 hours at l00 C under reduced pressure; it has a gel structure and a particle size of from 20 to 150 micrometers. The suspension in the reactor is then stirred steadily at 500 revolutions per minute. After 20 minutes, 584 parts/hour of methanol are introduced through line (2) and 1,611 parts of the distillate through line (3), at 800C and II bars, and correspondingly 2,195 parts of suspension are filtered through a suction line (5) fitted with a metal filter (pore diameter 10 micrometers) (4) and fed to the fractionating column (6). In the column (6), the unreacted components of the cracking distillate (hydrocarbons of 4 carbon atoms) are removed at the top via line (7) and the reaction mixture is taken off the column bottom via line (9). Per hour, the 2nd reactor (8) is fed with 904 parts of unreacted cracking distillate (101 parts of isobutylene) via line (7) and 55 parts of methanol via line (10). In the 2nd stirred reactor (8), the suspension formed is reacted in the presence of 220 parts of exchanger resin, whilst stirring at 700 revolutions per minute, at 800C and 11 bars. The exchanger resin is a sulfonated styrenedivinylbenzene copolymer resin which has been dehydrated before use by heating for 20 hours at 100"C under reduced pressure; it has a gel structure and a particle size of from 20 to 150 micrometers. 959 parts of suspension are filtered through a suction line (12) fitted with a metal filter (I I) (pore diameter 10 micrometers). In the column (13), 304 parts of unconverted cracking distillate, comprising 9 parts of isobutylene, are removed at the top via line (14) and the reaction mixture is taken off the column bottom via line (15). After 200 operating hours, 250,000 parts (99 ' of theory, based on reacted starting material II) of methyl tert.-butyl ether of boiling point 55"C/1,013 millibars are obtained (in addition to 24,800 parts of methanol) and are isolated from the mixture by extraction with water. The conversion is 79%, based on methanol employed and 98.9 /", based on starting material II employed.

EXAMPLE 6 A petroleum cracking distillate, having the composition described in Example 2, is used. A suspension of 10 parts of isobutanol, 50 parts of petroleum cracking distillate and 25 parts of exchanger resin is prepared in a stirred reactor by stirring at 500 revolutions per minute at 600C and 9.5 bars. The exchanger resin is a sulfonated styrene-divinylbenzene copolymer resin which has been dehydrated before use by heating for 20 hours at 1000C under reduced pressure; it has a gel structure and a particle size of from 20 to 150 micrometers. The suspension in the reactor is then stirred steadily at 500 revolutions per minute. After 20 minutes, 100 parts/hour of isobutanol and 177 parts/hour of petroleum cracking distillate are introduced at 600C and 9.5 bars and correspondingly 277 parts of suspension are filtered through a suction line fitted with a metal filter (pore diameter 10 micrometers) and are passed to a fractional distillation. After 100 hours' operation, 150 parts of isobutyl tert.-butyl ether (99.5 of theory, based on reacted starting material II) of boiling point 1200C, are obtained. The conversion is 85%, based on starting material III employed, and 80%, based on starting material II employed.

20.6 parts of isobutylene and 15 parts of isobutanol are recovered.

EXAMPLE 7 A suspension of 80 parts of sec.-butanol and 25 parts of exchanger resin is prepared in a stirred reactor by stirring at 500 revolutions per minute at 600C and 2.5 bars, and 60 parts of isobutylene are passed in. The exchanger resin is a sulfonated styrene-divinylbenzene copolymer resin which has been dehydrated before use by heating for 20 hours at 1000C under reduced pressure; it has a gel structure and a particle size of from 20 to 150 micrometers. The suspension in the reactor is then stirred steadily at 500 revolutions per minute. After 40 minutes, the reaction mixture is distilled. 39 parts (99 /" of theory, based on reacted starting material II) of sec.-butyl tert.-butyl ether of boiling point 120 C/1,013 millibars, are obtained in addition to 58 parts of unreacted sec.-butanol. The conversion is 28 /n of theory, based on sec.-butanol employed.

EXAMPLE 8 A suspension of 80 parts of n-butanol and 25 parts of exchanger resin is prepared in a stirred reactor by stirring at 500 revolutions per minute at 600C and 2.5 bars, and 60 parts of isobutylene are passed in. The exchanger resin is a sulfonated styrene-divinylbenzene copolymer resin which has been dehydrated before use by heating for 20 hours at 1000C under reduced pressure; it has a gel structure and a particle size of from 20 to 150 micrometers. The suspension in the reactor is then stirred steadily at 500 revolutions per minute. After 40 minutes, the reaction mixture is distilled. 72 parts (99% of theory, based on reacted starting material II) of n-butyl tert.-butyl ether of boiling point 1200C/l,0l3 millibars, are obtained in addition to 39 parts of unconverted n-butanol. The conversion is 51 /n of theory, based on n-butanol employed.

EXAMPLE 9 A suspension of 80 parts of isopropanol and 25 parts of exchanger resin is prepared in a stirred reactor by stirring at 500 revolutions per minute at 850C and 2.5 bars, and 75 parts of isobutylene are passed in. The exchanger resin is a sulfonated styrene-divinylbenzene copolymer resin which has been dehydrated before use by heating for 20 hours at 1000C under reduced pressure; it has a gel structure and a particle size of from 20 to 150 micrometers. The suspension in the reactor is then stirred steadily at 500 revolutions per minute. After 40 minutes, the reaction mixture is distilled. 25 parts (99 /n of theory, based on reacted starting material 11) of isopropyl tert.-butyl ether of boiling point 82"C/1,013 millibars, are obtained in addition to 67 parts of unreacted isopropanol. The conversion is 16% of theory, based on isopropanol employed.

EXAMPLE 10 A suspension of 80 parts of monomethylglycol ether and 25 parts of exchanger resin is prepared in a stirred reactor by stirring at 500 revolutions per minute at 85"C and 2.5 bars, and 60 parts of isobutylene are passed in. The exchanger resin is a sulfonated styrene-divinylbenzene copolymer resin which has been dehydrated before use by heating for 20 hours at 1000C under reduced pressure; it has a gel structure and a particle size of from 20 to 150 micrometers. The suspension in the reactor is then stirred steadily at 500 revolutions per minute. After 40 minutes, the reaction mixture is distilled. 97 parts (99 /O of theory, based on reacted starting material II) of methyl tert.-butyl glycol ether of boiling point 125"C/1,01 3 millibars, are obtained in addition to 24 parts of unreacted starting material III. The conversion is 70 /n of theory, based on starting material III employed.

WHAT WE CLAIM IS: 1. A process for the continuous manufacture of a tertiary aliphatic ether of the formula

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (23)

**WARNING** start of CLMS field may overlap end of DESC **. micrometers) and are passed to a fractional distillation. After 100 hours' operation, 150 parts of isobutyl tert.-butyl ether (99.5 of theory, based on reacted starting material II) of boiling point 1200C, are obtained. The conversion is 85%, based on starting material III employed, and 80%, based on starting material II employed. 20.6 parts of isobutylene and 15 parts of isobutanol are recovered. EXAMPLE 7 A suspension of 80 parts of sec.-butanol and 25 parts of exchanger resin is prepared in a stirred reactor by stirring at 500 revolutions per minute at 600C and 2.5 bars, and 60 parts of isobutylene are passed in. The exchanger resin is a sulfonated styrene-divinylbenzene copolymer resin which has been dehydrated before use by heating for 20 hours at 1000C under reduced pressure; it has a gel structure and a particle size of from 20 to 150 micrometers. The suspension in the reactor is then stirred steadily at 500 revolutions per minute. After 40 minutes, the reaction mixture is distilled. 39 parts (99 /" of theory, based on reacted starting material II) of sec.-butyl tert.-butyl ether of boiling point 120 C/1,013 millibars, are obtained in addition to 58 parts of unreacted sec.-butanol. The conversion is 28 /n of theory, based on sec.-butanol employed. EXAMPLE 8 A suspension of 80 parts of n-butanol and 25 parts of exchanger resin is prepared in a stirred reactor by stirring at 500 revolutions per minute at 600C and 2.5 bars, and 60 parts of isobutylene are passed in. The exchanger resin is a sulfonated styrene-divinylbenzene copolymer resin which has been dehydrated before use by heating for 20 hours at 1000C under reduced pressure; it has a gel structure and a particle size of from 20 to 150 micrometers. The suspension in the reactor is then stirred steadily at 500 revolutions per minute. After 40 minutes, the reaction mixture is distilled. 72 parts (99% of theory, based on reacted starting material II) of n-butyl tert.-butyl ether of boiling point 1200C/l,0l3 millibars, are obtained in addition to 39 parts of unconverted n-butanol. The conversion is 51 /n of theory, based on n-butanol employed. EXAMPLE 9 A suspension of 80 parts of isopropanol and 25 parts of exchanger resin is prepared in a stirred reactor by stirring at 500 revolutions per minute at 850C and 2.5 bars, and 75 parts of isobutylene are passed in. The exchanger resin is a sulfonated styrene-divinylbenzene copolymer resin which has been dehydrated before use by heating for 20 hours at 1000C under reduced pressure; it has a gel structure and a particle size of from 20 to 150 micrometers. The suspension in the reactor is then stirred steadily at 500 revolutions per minute. After 40 minutes, the reaction mixture is distilled. 25 parts (99 /n of theory, based on reacted starting material 11) of isopropyl tert.-butyl ether of boiling point 82"C/1,013 millibars, are obtained in addition to 67 parts of unreacted isopropanol. The conversion is 16% of theory, based on isopropanol employed. EXAMPLE 10 A suspension of 80 parts of monomethylglycol ether and 25 parts of exchanger resin is prepared in a stirred reactor by stirring at 500 revolutions per minute at 85"C and 2.5 bars, and 60 parts of isobutylene are passed in. The exchanger resin is a sulfonated styrene-divinylbenzene copolymer resin which has been dehydrated before use by heating for 20 hours at 1000C under reduced pressure; it has a gel structure and a particle size of from 20 to 150 micrometers. The suspension in the reactor is then stirred steadily at 500 revolutions per minute. After 40 minutes, the reaction mixture is distilled. 97 parts (99 /O of theory, based on reacted starting material II) of methyl tert.-butyl glycol ether of boiling point 125"C/1,01 3 millibars, are obtained in addition to 24 parts of unreacted starting material III. The conversion is 70 /n of theory, based on starting material III employed. WHAT WE CLAIM IS:

1. A process for the continuous manufacture of a tertiary aliphatic ether of the formula

where R', R2, R3 and R4 are identical or different and each is an aliphatic radical, and Rl and R4 may also be hydrogen, by reacting an alcohol with an isoolefin in the presence of a cation exchanger, wherein an isoolefin of the formula

where R2 and R3 have the above meanings, is continuously reacted with an aliphatic alcohol of the formula

where Rl and R4 have the above meanings, in the presence as catalyst of an organic cation exchanger containing sulfonic acid groups and having a particle size of from 10 to 200 micrometers, the exchanger being suspended in the liquid reaction mixture.

2. A process as claimed in Claim 1, in which the reaction is carried out whilst mixing the reaction mixture by stirring at a speed of at least 100 revolutions per minute or by introducing a shearing energy corresponding to the said rate of stirring.

3. A process as claimed in claim l or 2, in which the reaction is carried out with from 0.1 to 10 moles of starting material II per mole of starting material III.

4. A process as claimed in any of Claims I to 3, in which the reaction is carried out at from 30 to 1500C.

5. A process as claimed in any of Claims I to 3, in which the reaction is carried out at from 40 to 1300C.

6. A process as claimed in any of Claims I to 3, in which the reaction is carried out at from 50 to 1200C.

7. A process as claimed in any of Claims 1 to 6, in which the cation exchanger is a resin consisting of a sulfonated styrene-divinylbenzene copolymer or another sulfonated crosslinked styrene polymer or a phenol-formaldehyde or benzeneformaldehyde resin containing sulfonic acid groups.

8. A process as claimed in any of Claims I to 7, in which the reaction is carried out with an exchanger of particle size from 20 to 180 micrometers.

9. A process as claimed in any of Claims I to 7, in which the reaction is carried out with an exchanger of particle size from 25 to 150 micrometers.

10. A process as claimed in any of Claims I to 9, in which the cation exchanger has a gel-like structure.

II. A process as claimed in any of Claims I to 10, in which the reaction is carried out with the cation exchanger initially present in an amount of from I to 40 percent by weight, based on the weight of the total liquid mixture in the reaction space, in the reaction mixture undergoing formation.

12. A process as claimed in any of Claims I to li, in which the reaction is carried out whilst stirring at a speed of from 200 to 2,000 revolutions per minute.

13. A process as claimed in any of Claims I to 11, in which the reaction is carried out whilst stirring at a speed of from 300 to 1,000 revolutions per minute.

14. A process as claimed in any of Claims I to 13, wherein the isoolefin II has the formula given in Claim I in which R2 and R3, which are identical or different, are each alkyl of 1 to 7 carbon atoms.

15. A process as claimed in any of Claims I to 14, wherein the aliphatic alcohol III is a primary alcohol, R4 being hydrogen.

16. A process as claimed in Claim 15, wherein in the formula of the aliphatic alcohol III Rl is hydrogen or alkyl of I to 7 carbon atoms optionally interrupted by oxygen in the carbon chain and optionally substituted by chlorine, bromine, C13 alkyl, C13 alkoxy or by hydroxy attached to a CH2 group.

17. A process as claimed in any of Claims 1 to 16, wherein from 0.5 to 2 moles of isoolefin II are used per mole of aliphatic alcohol 111.

18. A process as claimed in any of Claims l to 17, wherein a mixture of aliphatic alcohols III is used.

19. A process as claimed in any of Claims I to 18, wherein the isoolefin II is reacted in admixture with one or more linear olefins, alkynes and/or alkanes.

20. A process for the manufacture of a tertiary aliphatic ether carried out substantially as described in any of the foregoing Examples.

21. Tertiary aliphatic ethers when manufactured by a process as claimed in any of Claims I to 20.

22. Fuel containing a tertiary aliphatic ether claimed in Claim 21 as an additive.

23. Anti-knock compounds, fuel additives, dyes, pesticides, drugs, emulsifiers, dispersing agents, stabilizers, antioxidants, plasticizers, corrosion inhibitors, disinfectants, seed dressings, anti-aging compounds, crop protection agents and scents when obtained from tertiary aliphatic ethers claimed in Claim 21.