Abstract:
Methods are provided for producing alkylbenzenes, such as propylbenzene, from aromatics, such as toluene, and alkenes, such as ethylene. Such methods comprise combining the toluene with about 100 ppm to about 350 ppm water and alkali metal catalyst, activating the catalyst at about 180° C. to about 220° C., adding the ethylene and conducting the synthesis reaction at about 130° C. to about 150° C.

Description:
BACKGROUND 
     Alkylbenzenes are useful, for example, as intermediates in the production of various end products. It is known that alkali metals, when reacted with alkylbenzenes, will displace benzylic hydrogens. The resulting alkylbenzene anion/alkali metal cation pair will undergo a reaction with olefins at certain temperatures to give alkylation products in which some or all saturated benzylic carbon atoms are alkylated in such a way as to replace some or all of the benzylic hydrogen atoms on a carbon atom with one aliphatic chain per benzylic hydrogen atom. Such reactions can yield a variety of products, depending on the number of saturated benzylic carbon atoms and the number of hydrogen atoms on a given benzylic carbon atom. In the commercial production of alkylbenzenes, a product of high purity is generally desired, and byproducts must be removed. Several patents and publications address issues related to providing suitable methods for commercial production of alkylbenzenes. See, e.g., U.S. Pat. No. 4,950,831 and U.S. Pat. No. 6,100,437. 
     A particular alkylbenzene, propylbenzene, can be used, e.g., in textile dyeing and printing, as a solvent for cellulose acetate in the manufacture of methylstyrene, and in various consumer products. 
     Various methods for production of propylbenzene are published in the literature. For example, publications indicate that propylbenzene can be made by alkylation of benzene with cyclopropane, by isomerization of cumene using zeolite, by Friedel-Crafts acylation of benzene with propionyl chloride, or by reaction of toluene and ethylene using NaK. 
     In spite of these publications, and efforts by others to improve the production of alkylbenzenes, to our knowledge propylbenzene is not widely produced commercially in significant quantities. Thus, economically-efficient methods that provide propylbenzene products of commercially suitable purity are needed. 
     THE INVENTION 
     This invention meets the above-described needs by providing methods comprising (a) combining at least aromatic hydrocarbon having an active hydrogen on a saturated alpha-carbon, water in an amount such that the water content is in the range of more than 100 ppm to about 350 ppm based on the content of the water and the aromatic hydrocarbon, and alkali metal to form a mixture; (b) maintaining the mixture at about 180° C. to about 220° C. for at least about 30 minutes; (c) cooling the mixture to about 150° C. to about 130° C.; (d) combining at least the mixture and alkene to form a reaction mixture; (e) maintaining the reaction mixture at about 130° C. to about 150° C. for longer than about 1 hour while agitating the reaction mixture at about 150 psig to about 300 psig; and (f) producing alkylbenzene. Further such methods are provided comprising (g) recovering from the reaction mixture unreacted aromatic hydrocarbon having an active hydrogen on a saturated alpha-carbon; and wherein at least a portion of the recovered unreacted aromatic hydrocarbon is used in (a). Also provided are methods comprising (a) combining at least toluene, water in an amount such that the water content is in the range of more than 100 ppm to about 350 ppm based on the content of the water and the toluene, and sodium-potassium alloy to form a mixture; (b) maintaining the mixture at about 180° C. to about 200° C. for at least about 30 minutes; (c) cooling the mixture to about 150° C. to about 130° C.; (d) combining at least the mixture and ethene to form a reaction mixture; (e) maintaining the reaction mixture at about 130° C. to about 150° C. for longer than about 1 hour while agitating the reaction mixture at about 150 psig to about 300 psig; (f) producing propylbenzene; and such methods are provided comprising (g) recovering from the reaction mixture unreacted toluene; and wherein at least a portion of the recovered unreacted toluene is used in (a). 
    
    
     
       FIGURE 
       The invention will be better understood by reference to  FIG. 1 , which is a process flow diagram representative of methods according to this invention. 
     
    
    
     AROMATIC HYDROCARBON 
     The aromatic hydrocarbon having an active hydrogen on a saturated alpha-carbon may be any such compound that is known to be useful in such reactions, such as toluene, ethylbenzene, n-propylbenzene (NPB), isopropylbenzene, n-butylbenzene, sec-butylbenzene, isobutylbenzene, n-eicosylbenzene, o-, m-, and p-xylenes, o-, m-, and p-ethyltoluenes, 1,3,5-trimethylbenzene, 1,2,4,5- and 1,2,3,5-tetramethylbenzenes, p-diisopropylbenzene, 1- and 2-methylnaphthalenes, dimethylnaphthalenes, 1-ethyl-4-n-octadecylnaphthalene, 1,4-di-n-pentylnaphthalene, 1,2,3,4-tetrahydronaphthalene, indan, cyclohexylbenzene, methylcyclohexylbenzene, diphenylmethane, etc. However, it is generally a hydrocarbon corresponding to the formula RR′R″CH, in which R is an aryl group of up to 20 carbons and each of R′ and R″ is independently selected from hydrogen and alkyl and aryl groups of up to about 20 carbons. The aromatic hydrocarbon typically comprises alkylbenzene having one or more ar-alkyl groups. A particularly suitable aromatic hydrocarbon is toluene. 
     Alkali Metal 
     As is known to those skilled in the art (see e.g., Cobb), alkali metal employed as a catalyst may be lithium, stadium, potassium, rubidium, or cesium; and it appropriately has its surface area increased by being finely divided or liquid. Particularly suitable alkali metals are potassium or potassium alloy, e.g., sodium-potassium alloy. A suitable alkali metal comprises sodium-potassium alloy having a potassium content of about 40 wt % to about 90 wt %. The amount of alkali metal used is a catalytic amount, generally about 2 mol % to about 10 mol %, based on the amount of either of the reactants when they are employed in equimolar amounts or on the amount of the major reactant when they are not utilized in equimolar amounts. 
     Alkene 
     The alkene that is used in the practice of the invention may be any of the alkenes that are known to be useful in such reactions, such as ethene, propene, 1-butene, 2-butene, isobutene, 1-pentene, 2-pentene, 3-methyl-1-butene, 2-methyl-2-butene, 1-hexene, 2-hexene, 3-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-2-pentene, 1-heptene, 2-heptene, 2-octene, 4-nonene, 1-decene, 2-decene, 1-dodecene, 3-tetradecene, 5-hexadecene, 6-methyl-4-heptadecene, 1-eicosene, etc. However, it is generally alkene corresponding to the formula QQ′C═CTT′, in which each of Q, Q′, T, and T′ is independently selected from hydrogen and alkyl groups of up to about 20 carbons. The alkene typically comprises up to about 20 carbons. Particularly suitable alkenes are ethylene and propylene. 
     DESCRIPTION 
     Referring to  FIG. 1 , methods according to this invention can comprise combining aromatic hydrocarbon as described herein, such as toluene, from container  10  (via line  11 ) and water from container  12  in reaction vessel  14 . If desired, as is shown in  FIG. 1 , water from container  12  can be fed into reaction vessel  14  via line  11 . Also, dispersant, such as tall oil, can be fed from container  12 , via line  11  if desired, into reaction vessel  14 . The water content fed into reaction vessel  14  can be in the range of more than 100 ppm to about 350 ppm based on the total content of the water plus the aromatic hydrocarbon. The water content can range from about 260 ppm to about 350 ppm, or from about 300 ppm to about 330 ppm. The water fed from container  12  can be from any suitable source and is typically potable water. Alkali metal, such as sodium-potassium alloy, can be fed from container  16 , via line  17 , into reaction vessel  14 . The combination/mixture of toluene, water, tall oil, and sodium-potassium alloy within reaction vessel  14  can be heated and maintained at about 180° C. to about 220° C. for at least about 30 minutes. In most cases, maintaining the combination at 180° C. to about 220° C. for longer than about 5 or 6 hours would destroy the catalyst. After the mixture in reaction vessel  14  is maintained within the desired temperature range for the desired time period, the mixture can be cooled to about 150° C. to about 130° C. An alkene as described herein, such as ethylene, can be fed into reaction vessel  14  from container  18  via line  19  and combined with the mixture to form a reaction mixture. The reaction mixture in reaction vessel  14  can be maintained at about 130° C. to about 150° C., or from about 138° C. to about 140° C., and about 150 psig to about 300 psig, for longer than one hour while being agitated by action of agitator  20 . Agitator  20  can be any suitable agitator, e.g., a flat pitch impeller. The reaction mixture can be transferred from reaction vessel  14  to quench vessel  22  via line  21 . Quench water from a suitable source (not shown) can be added to quench vessel  22 , and/or recycle quench water from container  24  can be fed to quench vessel  22  via line  25 . The reaction mixture and quench water/recycle quench water in quench vessel  22  can be agitated by action of agitator  26 . Quenched reaction mixture can be transferred from quench vessel  22  to settling phase vessel  24  via line  23 . In settling phase vessel  24 , aqueous phase  30  separates from organic phase  32 . Aqueous phase  30  can be recycled via line  25  to quench vessel  22  as recycle quench water. Build up of caustics in recycled quench water can result in less residual aromatics in aqueous phase  30  when separated from organic phase  32 , than would otherwise be present in aqueous phase  30 . Organic phase  32  from settling phase vessel  24  can be transferred to distillation feed vessel  34  via line  33 . Organics from distillation feed vessel  34  can be fed to distillation column  36  via line  35 . Unreacted aromatic hydrocarbon, e.g., toluene, can be fed/recycled to container  10  via line  37 . Heavy organics from distillation column  36  can be transferred to distillation column  38  via line  39 . Produced alkylbenzene, such as n-propylbenzene, can be transferred from distillation column  38  to product storage container  40  via line  41 . Heavy organics from distillation column  38  can be transferred to bottoms container  42  via line  43 . 
     The chemical reaction when toluene and ethylene are used in methods of this invention to produce propylbenzene can be shown as follows: 
     
       
                 
         
             
             
         
      
     
     Examples 
     The following examples are illustrative of the principles of this invention. It is understood that this invention is not limited to any one specific embodiment exemplified herein, whether in the examples or the remainder of this patent application. 
     In the examples listed in Table 1, the following method was used, except as otherwise indicated. Toluene in the amount shown and water in an amount such that the water content was in the range of more than about 100 ppm to about 350 ppm based on the content of the water and the toluene, and NAK in the amount shown were combined to form a mixture. Tall oil was added as a dispersant. The mixture was heated and maintained at the temperature, and for the time period, shown in the column headed “Catalyst Activation temp &amp; time”. The mixture was cooled to within the temperature range shown in the column headed “Temp range” and ethylene was added to the cooled mixture in the amount shown to form a reaction mixture. The reaction mixture was maintained within the temperature range shown in the column headed “Temp range” for the time shown in the column headed “Rxn time” while the reaction mixture was agitated. Product ratio (GC area %) data is given for toluene and n-propylbenzene (NPB), as well as for side products 3-phenylpentane (3-PP) and Indan. A flat pitch impeller was used to create high shear agitation. Note that in example ID&#39;s 19-21, insufficient water was used (i.e., less than 100 ppm water based on the content of the water and the toluene as determined by Karl-Fischer analysis). In example ID 26, too much water was used (i.e., more than 350 ppm water based on the content of the water and the toluene as determined by Karl-Fischer analysis). 
     
       
         
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
             
             
               
                   
                   
               
               
                   
                 Toluene 
                 NaK 
                 Ethylene 
                 Catalyst 
                 Temp 
                 Temp 
                 Pressure 
                 Pressure 
                 Rxn 
                   
               
               
                   
                 charge 
                 charge 
                 Charge 
                 Activation temp 
                 setpoint 
                 range 
                 setpoint 
                 range 
                 time 
                 Product ratio (GC area %) 
               
             
          
           
               
                 ID 
                 (lbs) 
                 (lbs) 
                 (lbs) 
                 (° C.) &amp; time 
                 (° C.) 
                 (° C.) 
                 (° C.) 
                 (psig) 
                 (hr) 
                 Toluene 
                 NPB 
                 3-PP 
                 Indan 
               
               
                   
               
             
          
           
               
                 1 
                 25000 
                 125 
                 1023 
                 180 - 1 hr 
                 140 
                 140-145 
                 270 
                 300 
                 2 
                 99.3 
                 0.5 
                 0 
                 0 
               
               
                 2 
                 25000 
                 125 
                 3000 
                 175-180 - 1 hr; 
                 140-145 
                 129-157 
                 270-300 
                 260-310 
                 4 
                 72.8 
                 21.7 
                 4.5 
                 0.08 
               
               
                   
                   
                   
                   
                 70-180 - 3 hr 
               
               
                 3 
                 25000 
                 125 
                 5500 
                 175-180 - 1 hr 
                 145-175 
                 145-175 
                 270-300 
                 260-300 
                 5 
                 47.3 
                 27.7 
                 20.9 
                 0.32 
               
               
                 4 
                 25000 
                 180 
                 2765 
                 171-177 - 1 hr 
                 150-155 
                 150-165 
                 300-350 
                 300-352 
                 3 
                 71.3 
                 18.6 
                 7.8 
                 0.20 
               
               
                 5 
                 25000 
                 125 
                 5501 
                 ~200 - 2.5 hr 
                 145 
                 140-145 
                 300 
                 285-300 
                 2 
                 43.1 
                 39.9 
                 15.0 
                 0.24 
               
               
                 6 
                 25000 
                 125 
                 5500 
                 200 - 6 hr; 145 - 2 hr 
                 145 
                 145-146 
                 300 
                 297-300 
                 3 
                 43.3 
                 37.0 
                 16.0 
                 0.62 
               
               
                 7 
                 25000 
                 132 
                 5501 
                 200 - 2 hr 
                 145 
                 144-146 
                 300 
                 299-302 
                 1.8 
                 40.2 
                 44.4 
                 13.7 
                 0.15 
               
               
                 8 
                 25400 
                 100 
                 4500 
                 200 - 2 hr 
                 145 
                 144-146 
                 300 
                 299-305 
                 4 
                 54.9 
                 30.8 
                 11.6 
                 0.34 
               
               
                 9 
                 25000 
                 130 
                 5500 
                 200 - 2 hr 
                 145 
                 144-146 
                 300 
                 300 
                 1.8 
                 39.3 
                 48.3 
                 12.0 
                 0.11 
               
               
                 10 
                 25000 
                 125 
                 5500 
                 200 - 2 hr 
                 145 
                 144-147 
                 300 
                 300 
                 2.3 
                 40.4 
                 42.7 
                 15.4 
                 0.09 
               
               
                 11 
                 25000 
                 130 
                 5500 
                 200 - 2 hr 
                 145 
                 145-147 
                 300 
                 300-302 
                 1.7 
                 40.5 
                 42.3 
                 15.5 
                 0.10 
               
               
                 12 
                 25000 
                 133 
                 5500 
                 200 - 2 hr 
                 145 
                 141-148 
                 300 
                 299-302 
                 1.7 
                 41.0 
                 42.8 
                 14.9 
                 0.08 
               
               
                 13 
                 25000 
                 131 
                 5500 
                 200 - 2 hr 
                 145 
                 143-148 
                 300 
                 299-301 
                 1.8 
                 42.3 
                 39.0 
                 17.1 
                 0.08 
               
               
                 14 
                 25000 
                 132 
                 5500 
                 200 - 2 hr 
                 145 
                 144-149 
                 300 
                 272 
                 1.3 
                 41.6 
                 40.2 
                 16.6 
                 0.03 
               
               
                 15 
                 25000 
                 130 
                 5500 
                 200 - 2.5 hr 
                 145 
                 145-150 
                 300 
                 270 
                 1.3 
                 42.5 
                 41.0 
                 15.1 
                 0.10 
               
               
                 16 
                 25000 
                 130 
                 5400 
                 200 - 2.5 hr 
                 142 
                 140-147 
                 300 
                 301 
                 1.3 
                 40.5 
                 44.8 
                 13.4 
                 0.10 
               
               
                 17 
                 25000 
                 130 
                 5500 
                 200 - 2.5 hr 
                 140 
                 138-144 
                 300 
                 302 
                 1.7 
                 39.3 
                 46.5 
                 12.6 
                 0.11 
               
               
                 18 
                 25000 
                 130 
                 5500 
                 200 - 2.5 hr 
                 140 
                 138-143 
                 300 
                 303 
                 1.9 
                 38.6 
                 46.6 
                 13.5 
                 0.02 
               
               
                 19 
                 25000 
                 130 
                 5500 
                 200 - 2.5 hr 
                 140 
                 137-144 
                 300 
                 302 
                 1.7 
                 40.8 
                 41.9 
                 16.0 
                 0.07 
               
               
                 20 
                 25000 
                 130 
                 5500 
                 200 - 2.5 hr 
                 140 
                 138-144 
                 300 
                 300 
                 1.3 
                 42.7 
                 38.1 
                 17.7 
                 0.02 
               
               
                 21 
                 25000 
                 130 
                 5500 
                 200 - 2.5 hr 
                 138 
                 136-143 
                 300 
                 272 
                 1.2 
                 41.7 
                 38.6 
                 18.1 
                 0.09 
               
               
                 22 
                 25000 
                 130 
                 5500 
                 200 - 2.5 hr 
                 138 
                 135-142 
                 300 
                 300 
                 1.5 
                 39.0 
                 45.3 
                 14.1 
                 0.15 
               
               
                 23 
                 25000 
                 130 
                 5500 
                 200 - 2.5 hr 
                 138 
                 135-142 
                 300 
                 300 
                 1.9 
                 38.3 
                 47.8 
                 12.4 
                 0.14 
               
               
                 24 
                 25000 
                 130 
                 5500 
                 200 - 2.5 hr 
                 138 
                 135-142 
                 300 
                 300 
                 2.0 
                 39.8 
                 46.1 
                 12.6 
                 0.13 
               
               
                 25 
                 25000 
                 130 
                 5500 
                 200 - 2.5 hr 
                 138 
                 135-142 
                 300 
                 300 
                 2.1 
                 37.6 
                 48.7 
                 12.2 
                 0.03 
               
               
                 26 
                 25000 
                 130 
                 5500 
                 200 - 2.5 hr 
                 138 
                 135-140 
                 300 
                 300 
                 5.9 
                 46.5 
                 36.3 
                 14.2 
                 0.25 
               
               
                 27 
                 25400 
                 130 
                 5500 
                 200 - 2.5 hr 
                 140 
                 136-140 
                 300 
                 300 
                 2.8 
                 38.5 
                 47.9 
                 12.1 
                 0.02 
               
               
                 28 
                 25000 
                 130 
                 5500 
                 200 - 2.5 hr 
                 138 
                 137-139 
                 300 
                 300 
                 2.7 
                 39.6 
                 47.1 
                 11.6 
                 0.13 
               
               
                 29 
                 25000 
                 130 
                 5500 
                 200 - 2.5 hr 
                 138 
                 137-139 
                 300 
                 300 
                 3.6 
                 38.9 
                 47.0 
                 12.4 
                 0.14 
               
               
                 30 
                 25000 
                 130 
                 5500 
                 200 - 2.5 hr 
                 138 
                 137-139 
                 300 
                 300 
                 2.5 
                 35.4 
                 51.0 
                 12.3 
                 0.09 
               
               
                 31 
                 25000 
                 130 
                 5500 
                 200 - 2.5 hr 
                 138 
                 137-139 
                 300 
                 300 
                 3.5 
                 37.6 
                 48.9 
                 12.1 
                 0.02 
               
               
                 32 
                 25000 
                 130 
                 5500 
                 200 - 2.5 hr 
                 138 
                 137-139 
                 300 
                 300 
                 2.5 
                 38.1 
                 48.2 
                 12.2 
                 0.12 
               
               
                 33 
                 25000 
                 130 
                 5500 
                 200 - 2.5 hr 
                 138 
                 137-139 
                 300 
                 300 
                 2.2 
                 37.6 
                 48.1 
                 12.3 
                 0.12 
               
               
                 34 
                 25000 
                 130 
                 5500 
                 200 - 2.5 hr 
                 138 
                 137-139 
                 300 
                 300 
                 2.8 
                 37.7 
                 48.2 
                 12.4 
                 0.13 
               
               
                 35 
                 25000 
                 117 
                 5500 
                 200 - 2.5 hr 
                 138 
                 137-139 
                 300 
                 300 
                 5.5 
                 44.2 
                 38.4 
                 14.7 
                 0.22 
               
               
                   
               
             
          
         
       
     
     In example ID 1, the reactor was wet. In example ID&#39;s 2-4 there was poor catalyst activation. In example ID 6, the catalyst was heated for too long. In example ID 8, insufficient NaK was used. 
     Advantages to this invention, in addition to good recovery of alkylbenzene with low levels of impurities, include recycle of unreacted toluene. Quench water can also be reused. 
     It is to be understood that the reactants and components referred to by chemical name or formula anywhere in the specification or claims hereof, whether referred to in the singular or plural, are identified as they exist prior to being combined with or coming into contact with another substance referred to by chemical name or chemical type (e.g., another reactant, solvent, or etc.). It matters not what chemical changes, transformations and/or reactions, if any, take place in the resulting mixture or solution or reaction medium as such changes, transformations and/or reactions are the natural result of bringing the specified reactants and/or components together under the conditions called for pursuant to this disclosure. Thus the reactants and components are identified as ingredients to be brought together in connection with performing a desired chemical reaction or in forming a mixture to be used in conducting a desired reaction. Accordingly, even though the claims hereinafter may refer to substances, components and/or ingredients in the present tense (“comprises”, “is”, etc.), the reference is to the substance, component or ingredient as it existed at the time just before it was first contacted, combined, blended or mixed with one or more other substances, components and/or ingredients in accordance with the present disclosure. Whatever transformations, if any, which occur in situ as a reaction is conducted is what the claim is intended to cover. Thus the fact that a substance, component or ingredient may have lost its original identity through a chemical reaction or transformation during the course of contacting, combining, blending or mixing operations, if conducted in accordance with this disclosure and with the application of common sense and the ordinary skill of a chemist, is thus wholly immaterial for an accurate understanding and appreciation of the true meaning and substance of this disclosure and the claims thereof. 
     While the present invention has been described in terms of one or more preferred embodiments, it is to be understood that other modifications may be made without departing from the scope of the invention, which is set forth in the claims below.