PROCESS FOR PREPARING CHLOROHYDRINS

Abstract: A process for hypochlorinating unsaturated alpha-olefins to produce chlorohydrins which comprises forming a microemulsion of water and an unsaturated alpha-olefin and then adding an oxidant to the microemulsion under conditions sufficient to form the chlorohydrins. The microemulsion is formed by adding a non-nucleophilic surfactant and, optionally, a co-surfactant, to the mixture of water and unsaturated alpha-olefin.

Description: PROCESS FOR PREPARING CHLOROHYDRINS This invention relates to the preparation of chlorohydrins. More particularly, this invention relates to the preparation of chlorohydrins by hypochloπnation of alpha-olefins. The chlorohydrins are useful as intermediates in the preparation of epoxides. Conventional hypochloπnation technology involves the reaction of chlorine with an alpha-olefin in water to yield the corresponding chlorohydnn. This reaction results in the formation of an excess oil phase due to the incompatibility of olefin with water or due to the formation of water-insoluble by-products. This oil phase is thought to serve as a locus for the production of undesired by-products such as dichlorides and ethers. To compensate for the incompatibility of olefin or by-products with water and reduce the formation of excess oil, large amounts of water relative to the olefin and intense mechanical mixing are used. This practice, however, causes in the subsequent dehydrochlonnation of the chlorohydnn, the formation of significant volume of aqueous effluents containing organic impurities, the purification of which requires expensive treatments. U.S. Patent 5,146,011 describes a process for preparing chlorohydrins by reacting a concentrated, aqueous solution of hypochiorous acid with an unsaturated organic compound having from 2 to 10 carbon atoms and selected from the group consisting of substituted and unsubstituted olefins and cyclic olefins The process is optionally carried out in the presence of a surfactant such as nonylphenol ethoxylate, al yldimethylbenzylammonium chloride and sodium dodecylbenzenesulfate, all of which contain an aromatic ring. It is known that any surfactant which contains an aromatic ring is subject to rapid oxidative reaction with chlorine or HOCI in the reaction mixture. The reaction is at temperatures from the freezing point of water up to 55°C. The low reaction temperature requires use of heat exchange equipment to remove the heat of reaction. The process requires the use of high concentration (greater than 10 weight percent, preferably from 20 to 65, most preferably from 35 to 55 percent by weight) HOCI solutions. British Patent Application 2 029 821 A describes a process for preparing glycerol dichlorohydnns by reacting chlorine and an emulsion of allyl chloride in water. The process requires the preparation of an emulsion of allyl chloride in water using a static mixer prior to feeding the emulsion to the reactor To facilitate the formation of the allyl chloride- water emulsion, an emulsifier, such as a non-ionic or anionic emulsifier, is added to the allyl chloride-water mixture In this process tne reaction between the allyl chloride-water emulsion and chlorine takes place in the oily phase which produces undesirable by-products. It would be desirable to provide a process for preparing chlorohydrins which do not have the disadvantages of the known processes described above. In a first aspect, this invention is a process for hypochlorinating unsaturated alpha-olefins to produce chlorohydrins which comprises forming a microemulsion of water and an unsaturated alpha-olefin and then adding an oxidant to the microemulsion under conditions sufficient to form the chlorohydnn. In general, the process for hypochlorinating unsaturated alpha-olefins to produce chlorohydrins comprises forming a microemulsion of water and an unsaturated alpha-olefin and then adding an oxidant to the microemulsion under conditions sufficient to form the chlorohydrins. The resulting microemulsion also comprises water-insoluble reaction by-products. Microemulsions are optically isotropic, transparent or translucent, and thermodynamicaliy stable dispersions of two immiscible liquids stabilized by a combination of nonionic amphipatic surface active materials and long-chain alcohols or amines. Their properties are time independent. They are independent of the order of mixing, and they return to their original state when subjected to a small disturbance which is subsequently relaxed. On the other hand, emulsions are thermodynamicaliy unstable. The drops of dispersed phase are generally large, perhaps larger than 0.1 μm, so that emulsions often take on a milky rather than the transparent or translucent appearance generally associated with microemulsions. The average drop size of emulsions grows continuously with time, which is a manifestation of thermodynamic instability. When exposed to a body force proportional to the mass, such as a gravitational field, emulsions will ultimately separate into two distinct phases. The formation of an emulsion involves an increase in the interfacial area between two immiscible phases and is accompanied by an increase in free energy. For the formation of a microemulsion, the interfacial tension has to be lowered to very low values, which is done by adsorption at the interface of a surface active material. For emulsions, no such interfacial tension lowering is needed to form the emulsions. Although not intended to be bound by theory, it is believed that when the interfacial tension is lowered to near zero, the system emulsifies spontaneously, creating a microemulsion. Microemulsions are described in "Microemulsions And Related Systems". 1988, Bourell & Schecter, Marcel Dekker Inc. New York and U.S. Patent 5,597,792. In general, the microemulsion is prepared by mixing water and an unsaturated alpha-olefin and then adding to the mixture a surfactant which is capable of forming a microemulsion of the olefin in water in the presence of the reaction products. The microemulsion of water and unsaturated alpha-olefin is spontaneously formed upon the addition of the surfactant to the water and olefin mixture. Preferably, the surfactant is combined with a co-surfactant. Preferably, the reaction product (for example a chlorohydnn) is used as the co-surfactant. Optionally, additional co-surfactants may be added to enhance formation of the microemulsion. The surfactant may be dissolved (premixed) in either the starting oiefinic substrate or the water, depending on the solubility characteristics of the specific surfactant utilized. While emulsified particles typically do not have dynamic interface and exchange with other particles, microemulsified oil has very rapidly exchanging oil phase(s) and dynamic interface which greatly facilitate phase transfer and interfacial kinetics, both of which are desirable and necessary for improved chlorohydnn selectivity. The unsaturated alpha-olefins which can be employed in the practice of the present invention for preparing the chlorohydrins include unsaturated organic compounds containing from 2 to 24 carbon atoms and selected from the group consisting of substituted and unsubstituted olefins, diolefins and cyclic olefins, wherein the substituent(s) is alkyl, phenyl, or alkyiphenyl. Examples of these olefins are 1 -pentene, 1-octene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-eicosene, 2-hexene, 4-decene, 5-dodecene, 7-tetradecene, and 9-eicosene. Mixtures of these olefins can also be hypochlorinated to form chlorohydrins. The bis allyl ethers can also be employed in the practice of the present invention. The surfactants which can be employed in the practice of the present invention for preparing the chlorohydrins are preferably non-nucleophilic. The term "non- nucleophilic" as used herein, refers to surfactants which do not readily react with chloronium ion, the key reactive intermediate formed by reaction of chlorine with olefin. Additionally, the surfactant should not readily react with chlorine. The non-nucleophilic surfactants which can be employed in the practice of the present invention for preparing the chlorohydrins include alpha-olefin sulfonates, such as those prepared from 1-octene up through C 20 to C 24 alpha-olefin (see I Yamane, O. Okumura; "Surfactants: AOS" in Alpha Olefins Applications Handbook, G. R. Lapin and J. D. Sauer Ed.; Marcel Dekker, New York, NY, 1989, pp. 201 -239); quaternary amines, and alpha-olefin carboxylates. The quaternary amines which can be employed in the practice of the present invention include dodecyltrimethyl ammonium chloride, octadecyl trimethyl ammonium chloride, octadecyl pyridium chloride, didodecyldimethyl ammonium chloride, tallow ammonium chloride and 1-benzyl-2-hexadecyl ammonium chloride. Other surfactants which can be employed in the practice of the present invention include alkyl sulfonates, alkyl sulfates, dialkyl sulfosuccinates, fatty acid salts, and alkyl trimethyl ammonium chlorides. The co-surfactants which can be employed in the practice of the present invention include non-nucleophilic alcohols and carboxylates, and hydrophilic organic acids such as acetic acid, propionic acid, and butyric acid. The preferred co-surfactants are t-butanol, 1 ,1 -dimethyl-1 -propanol and 1 ,1-dimethyl-1-butanol, the most preferred being the chlorohydrins themselves which are formed during the reaction. The oxidants which can be employed in the practice of the present invention for preparing the chlorohydrin include chlorine, hypochiorous acid (HOCL) and tert-butylhypochlorite (t-BuOCL). The conditions at which the hypochlorination reaction is most advantageously conducted are dependent on a variety of factors, including the specific reactants and catalyst employed, if any. In general, the reaction is conducted at room temperature up to 100°C. Either plug flow reactor conditions or continuous stirred tank reactor (CSTR) conditions can be employed. With the latter reactor design, one can optionally add both caustic and chlorine to the reaction vessel in order to maintain a given pH, usually between pH =1 and pH =7, a process which is sometimes referred to as a half bleach process. The time and temperature most advantageously employed will vary depending on the specific reactants employed, particularly their reactivity. In general, the reaction temperature to form the chlorohydrins is from 0°C to 120°C and, most preferably, from 20°C to 80°C, and for a time sufficient for the reaction to occur, which may be as short as 10 seconds in a continuous or plug flow reactor. Preferably, such time period is from 1 minute to 2 hours, more preferably from 5 minutes to 1/2 hour and, most preferably, from 10 minutes to 1/4 hour. The time indicated is residence time in a continuous reactor regime. The concentrations at which the reactants are most advantageously employed are dependent on a variety of factors including the specific alpha-olefins employed and the chlorohydrins being prepared. In general, the water to alpha-olefins volume ratio is at least 5 to 1 and preferably at least 20 to 1. In most cases, the water to alpha-olefins volume ratio does not exceed 100 to 1. In general, the oxidants can be employed in an amount of from 0.8 to 1.2 equivalents based on olefin, preferably, from 0.9 to 1.1 , more preferably from 0.95 to 1.05 and, most preferably 1.0 equivalent, based on olefin. Normally the oxidant: olefin ratio is 1 :1 at standard reaction conditions for hypochlorination processes. The amount of surfactants which can be employed is, in general, from 0.01 to 5 weight percent, preferably, from 0.1 to 2 weight percent, more preferably from 0.2 to 1.5 weight percent and, most preferably from 0.3 to 1.0 weight percent, based on the weight of the olefin. The following working examples are given to illustrate the invention and should not be construed as limiting its scope. Unless otherwise indicated, all parts and percentages are by weight. Example 1 - Hypochlorination of 1 -octene with t-BuOCL in water Into a 500 mL jacketed resin kettle was added 200 iτiL of water, 0.625 g of C 20 - 24 alpha-olefin sulfonate (sodium salt, 40 percent in water) and 0.4 g of sodium sulfate. The reaction vessel was fitted with constant speed, variable torque mechanical stirrer, pH meter, thermometer, dry ice condenser vented to a bubbler, and septum. The mixture was stirred at 500 rpm and heated to 40°C and t-BuOCL (98 percent, 5.32 g, 0.0491 mole) and 1-octene (5 g, 7.37 mL, 0.045 mole) were added at equimolar rates using syringe pumps over a 1 hour period. After the addition was complete, NaOH was added (0.05 mole) until the pH reached 9.4 to convert the chlorohydrins formed to the corresponding epoxides. The solution was analyzed by GC which showed 92 percent 1 ,2-epoxyoctane, 1.4 percent 1 ,2- dichlorooctane and 6.5 percent bisether by-products. Example 2 - Hypochlorination of 1 -hexene with t-BuOCL in water Into a 500 mL jacketed resin kettle was added 200 mL of water, 0.625 g of C 20 . 24 alpha-olefin sulfonate (sodium salt, 40 percent in water) and 0.4 g of sodium sulfate. The reaction vessel was fitted with constant speed, variable torque mechanical stirrer, pH meter, thermometer, dry ice condenser vented to a bubbler, and septum. NaOH was added until the pH reached 10. The mixture was stirred at 500 rpm and heated to 40°C and t- BuOCL (98 percent, 7.74 g, 0.0713 mole) and 1 -hexene (5 g, 7.4 mL, 0.0594 mole) were added at equimolar rates using syringe pumps over a 1 hour period. After the addition was complete, NaOH was added (0.05 mole) until the pH reached 10 to convert the chlorohydrins formed to the corresponding epoxides. The solution was analyzed by GC which showed 95 percent 1 ,2-epoxyhexane, 2.7 percent 1 ,2-dichlorohexane and 3.2 percent bisether by- products. Example 3 Into a 500 mL jacketed resin kettle equipped with a mechanical stirrer, pH probe, chlorine gas bubbler, and addition pumps for adding olefin and aqueous sodium hydroxide was placed 400 mL of water and 0.09 g of Sodium C, 4 . 16 alpha-olefin sulfonate. The mechanical stirrer was set at 2000 rpm. To this was added over 5 minutes, 8 g of hexene (0.095 moles), 6.75 g of Chlorine gas and sufficient aqueous NaOH to maintain the pH at 6.5 to 7.0. After this time 20 mL of 5N NaOH was added to the reactor to convert the chlorohydrins formed to the corresponding epoxides. The reactor contents were analyzed via Gas Chromatography and gave the following results: 75.2 percent Epoxy Hexane 13.1 percent Dichlorohexane 11.7 percent Bis-(chlorohexyl ether) Example 4 The procedure of Example 3 was repeated except 0.045 g of sodium C ]4.)6 alpha-olefin sulfonate was added instead of 0.09 g. The reactor contents were analyzed via Gas Chromatography and gave the following results: 70.2 percent Epoxy Hexane 17.0 percent Dichlorohexane 12.8 percent Bis-(chlorohexyl ether) Example 5 The procedure of Example 3 was repeated except 0.0225 g of sodium C 14 . 16 alpha-olefin sulfonate was added instead of 0.09 g. The reactor contents were analyzed via Gas Chromatography and gave the following results: 48.6 percent Epoxy Hexane 30.6 percent Dichlorohexane 20.8 percent Bis-(chlorohexyl ether) Example 6 The procedure of Example 3 was repeated except 0.225 g of sodium dodecyl sulfate instead of sodium C 14 l6 alpha-olefin sulfonate was added. The reactor contents were analyzed via Gas Chromatography and gave the following results: 84.5 percent Epoxy Hexane 6.2 percent Dichlorohexane 9.3 percent Bis-(chlorohexyl ether) Example 7 The procedure of Example 3 was repeated except 0.1125 g of sodium dodecyl sulfate instead of sodium C(14-16) alpha-olefin sulfonate was added. The reactor contents were analyzed via gas chromatography and gave the following results: 77.4 percent Epoxy Hexane 11.1 percent Dichlorohexane 11.5 percent Bis-(chlorohexyl ether) Example 8 The procedure of Example 3 was repeated except 0.056 g of sodium dodecyl sulfate instead of sodium C 14.t6 alpha-olefin sulfonate was added. The reactor contents were analyzed via gas chromatography and gave the following results: 60.9 percent Epoxy Hexane 22.1 percent Dichlorohexane 17.0 percent Bis-(chlorohexyl ether) Example 9 The procedure of Example 3 was repeated except 0.90 g of Steol CS-130 (0.220 g active sulfates of ethoxylated alcohols) instead of sodium C- 14 16 alpha-olefin sulfonate was added. The reactor contents were analyzed via gas chromatography and gave the following results: 78.0 percent Epoxy Hexane 10.8 percent Dichlorohexane 1 1 .2 percent Bis-(chlorohexyl ether) Example 10 The procedure of Example 3 was repeated except 0.45 g of Steol CS-130 (0.110 g active sulfates of ethoxylated alcohols) instead of sodium C 14. , 6 alpha-olefin sulfonate was added. The reactor contents were analyzed via gas chromatography and gave the following results: 79.9 percent Epoxy Hexane 1 1.5 percent Dichlorohexane 8.6 percent Bis-(chlorohexyl ether) Example 1 1 The procedure of Example 3 was repeated except 0.225 g of Steol CS-130 (0.055 g active sulfates of ethoxylated alcohols) instead of sodium C 14.16 alpha-olefin sulfonate was added. The reactor contents were analyzed via Gas Chromatography and gave the following results: 67.8 percent Epoxy Hexane 16.9 percent Dichlorohexane 15.3 percent Bis-(chlorohexyl ether) Comparative Example A The procedure of Example 3 was repeated except 0.225 g of sodium octyl sulfonate instead of sodium C 14. , 6 alpha-olefin sulfonate was added. The reactor contents were analyzed via gas chromatography and gave the following results: 38.9 percent Epoxy Hexane 41.9 percent Dichlorohexane 19.2 percent Bis-(chiorohexyl ether) No microemulsification of product was observed. Instead, macroemulsions formed. Example 12 The procedure of Example 3 was repeated except 0.225 g of sodium decyl sulfonate instead of sodium C l4 . 16 alpha-olefin sulfonate was added. The reactor contents were analyzed via gas chromatography and gave the following results: 68.7 percent Epoxy Hexane 19.8 percent Dichlorohexane 1 1.5 percent Bis-(chlorohexyl ether) Example 13 The procedure of Example 3 was repeated except 0.225 g of sodium dodecyl sulfonate instead of sodium C l4.16 alpha-olefin sulfonate was added. The reactor contents were analyzed via gas chromatography and gave the following results. 81.1 percent Epoxy Hexane 8.2 percent Dichlorohexane 10.7 percent Bis-(chlorohexyl ether) Comparative Example B The procedure of Example 3 was repeated except 0.225 g of sodium hexadecyl sulfonate instead of sodium C 14.16 alpha-olefin sulfonate was added. The reactor contents were analyzed via gas chromatography and gave the following results: 45.8 percent Epoxy Hexane 31.8 percent Dichlorohexane 22.4 percent Bis-(chlorohexyl ether) No microemulsification of product was observed. Instead, macroemulsions formed. Comparative Example C The procedure of Example 3 was repeated except no surfactant was added. The reactor contents were analyzed via gas chromatography and gave the following results. 30.1 percent Epoxy Hexane 52.3 percent Dichlorohexane 17.6 percent Bιs-(chlorohexyl ether) Example 14 Into a 500 mL jacketed resin kettle equipped with a mechanical stirrer, pH probe, chlorine gas bubbler, and an addition pump for adding olefin was placed 400 mL of water and 0.20 g of sodium C 14 16 alpha-olefin sulfonate The mechanical stirrer was set at 2000 rpm. To this was added over 40 minutes, 20 g of allyl chloride (0.264 moles) and 18.56 g of Chlorine gas. The reactor contents were analyzed via gas chromatography and gave the following results. 95.56 percent Allyl chloride Chlorohydnn 3.76 percent Tπchloropropane 0.68 percent dichloropropyl ethers Example 15 Into a 500 mL jacketed resin kettle equipped with a mechanical stirrer, pH probe, chlorine gas bubbler, and an addition pump for adding olefin was placed 400 mL of water and 0.20 g of sodium C 14 16 alpha-olefin sulfonate The mechanical stirrer was set at 750 rpm. To this was added over 40 minutes, 20 g of allyl chloride (0.264 moles) and 18.56 g of chlorine gas. The reactor contents were analyzed via gas chromatography and gave the following results: 93.52 percent Allyl chloride Chlorohydnn 5.36 percent Tnchloropropane 1.16 percent dichloropropyl ethers Example 16 Into a 500 mL jacketed resin kettle equipped with a mechanical stirrer, pH probe, chlorine gas bubbler, and an addition pump for adding olefin was placed 400 mL of water and 0.10 g of sodium C 14 ]6 alpha-olefin sulfonate. The mechanical stirrer was set at 750 rpm. To this was added over 40 minutes, 20 g of allyl chloride (0.264 moles) and 18.56 g of chlorine gas. The reactor contents were analyzed via gas chromatography and gave the following results. 93.65 percent Allyl chloride Chlorohydnn 5.23 percent Tnchloropropane 1 12 percent dichloropropyl ethers Example 17 Into a 500 mL jacketed resin kettle equipped with a mechanical stirrer, pH probe, chlorine gas bubbler, and an addition pump for adding olefin was placed 400 mL of water and 0.02 g of sodium C, 4 16 alpha-olefin sulfonate The mechanical stirrer was set at 750 rpm. To this was added over 40 minutes, 20 g of allyl chloride (0.264 moles) and 18.56 g of Chlorine gas. The reactor contents were analyzed via gas chromatography and gave the following results: 85.82 percent Allyl chloride Chlorohydnn 10.27 percent Tnchloropropane 3.91 percent dichloropropyl ethers Comparative Example D Into a 500 mL jacketed resin kettle equipped with a mechanical stirrer, pH probe, chlorine gas bubbler, and an addition pump for adding olefin was placed 400 mL of water. The mechanical stirrer was set at 750 rpm To this was added over 40 minutes, 20 g of allyl chloride (0.264 moles) and 18.56 g of chlorine gas. The reactor contents were analyzed via gas chromatography and gave the following results. 61.22 percent Allyl chloride Chlorohydnn 33.85 percent Tnchloropropane 4.93 percent dichloropropyl ethers Comparative Example E Into a 500 mL jacketed resin kettle equipped with a mechanical stirrer, pH probe, chlorine gas bubbler, and an addition pump for adding olefin was placed 400 mL of water. The mechanical stirrer was set at 2000 rpm To this was added over 40 minutes, 20 g of allyl chloride (0.264 moles) and 18.56 g of Chlorine gas. The reactor contents were analyzed via Gas Chromatography and gave the following results 74.13 percent Allyl chloride Chlorohydnn 17.80 percent Tnchloropropane 8.07 percent dichloropropyl ethers In the above examples, Examples 3-5, 6-8 and 9-1 1 demonstrate the dependence of chlorohydrin yield on the amount of surfactant for the preparation of epoxy hexene using three surfactants which exhibited three phase microemulsion behavior. Examples 12 and 13 and Comparative Examples A and B show the effect of alkyl tail length on chlorohydrin yield. The surfactants used in Comparative Examples A and B gave emulsions and resulted in only slight improvements in chlorohydrin yield while the surfactants used in Examples 12 and 13 gave microemulsions and resulted in substantially better overall chlorohydrin yields. In Comparative Example C, no surfactant was used, and a poor yield was obtained. Examples 14-17 and Comparative Examples D and E describe the hypochlorination of allyl chloride with chlorine. Examples 14-17 show the effect of added surfactant as well as agitation rate on chorohydrin yield. Comparative Examples D and E show the yields obtained when no surfactant was added at the two agitation rates used.

Claims: WHAT IS CLAIMED IS: 1. A process for hypochlorinating unsaturated alpha-olefins to produce chlorohydrins, the process containing the steps of forming a microemulsion of water and an unsaturated alpha-olefin and adding an oxidant to the microemulsion under conditions sufficient to form the chlorohydrins. 2. The process of Claim 1 wherein the unsaturated alpha-olefin is an unsaturated organic compound containing from 2 to 24 carbon atoms. 3. The process of Claim 2 wherein the unsaturated alpha-olefin is a substituted or unsubstituted olefin, diolefin or cyclic olefin, wherein the substituent(s) is alkyl, phenyl, or alkylphenyl. 4. The process of Claim 3 wherein the alpha-olefin is 1-octene or 1-hexene. 5. The process of any of the above claims wherein the oxidant is chlorine, hypochiorous acid or tert-butylhypochlorite. 6. The process of any of the above claims wherein the microemulsion of water and unsaturated alpha-olefin is prepared by adding a non-nucleophilic surfactant to the alpha-olefin or water and then blending the water and the olefin under conditions sufficient to form a microemulsion. 7. The process of any of the above claims wherein the microemulsion of water and unsaturated alpha-olefin is prepared by blending the water and the olefin and then adding a non-nucleophilic surfactant to the blend under conditions sufficient to form a microemulsion. 8. The process of any of the above claims wherein the hypochlorination reaction is conducted at 0°C to 120°C and for a time sufficient for the reaction to occur. 9. The process of any of the above claims wherein the water and the alpha- olefin are employed in a water to alpha-olefin volume ratio of at least 5 to 1. 10. The process of any of the above claims wherein the oxidant is employed in an amount of from 0.8 to 1.2 equivalents based on olefin.

Inventors: FERRITTO MICHAEL S, GREEN DANIEL PATRICK, KLIER JOHN, TUCKER CHRISTOPHER J, FERRITTO, MICHAEL, S., GREEN, DANIEL, PATRICK, KLIER, JOHN, TUCKER, CHRISTOPHER, J.
Applicants: DOW CHEMICAL CO, THE DOW CHEMICAL COMPANY
Application year: 1999
Main classification: C07C29
IPC codes: C07C29, C07C31, C07D301, C07D303