227
Ind. Eng. Chem. Res. 1991,30, 227-231
Ei = instantaneous reaction factor, defined by e q 11,dimensionless
Ha = Hatta number for an irreversible gas-liquid
second-order reaction, defined by e q 10,dimensionless Ha' = parameter defined by e q 13, dimensionless Haexp= experimental Hatta number, obtained by trial a n d error from eqs 10-13 and 17,dimensionless Ha, = Hatta number for a n irreversible gas-liquid pseudomth-order reaction, defined by e q 6,dimensionless k = pseudo rate constant of the direct reaction between ozone and resorcinol or phloroglucinol, M-' s-l kd = ozone self-decomposition rate constant, M-' s-l kL = liquid-phase mass-transfer coefficient, m s-l [O,]= dissolved ozone concentration, M [O*,]= ozone solubility, ozone concentration at t h e gas-water interface, M [O*,],= critical ozone solubility, M t = ozonation time, s x = normal distance at the gas-water interface, m z = stoichiometric ratio of the direct reaction between ozone and the phenol, mol of ozone consumed per mol of resorcinol or phloroglucinol consumed Greek Letters
6 = liquid film thickness, m
x = parameter defined by e q 16,dimensionless Registry No. Ozone, 10028-15-6;resorcinol, 108-46-3; phloroglucinol, 108-73-6.
Literature Cited Buhler, R. E.; Staehelin, J.; Hoign6, J. Ozone Decomposition in Water Studied by Pulse Radiolysis. I. H02/O; and H03/0< as Intermediates. J. Phys. Chem. 1984,88,-256&2564. Camacho, F.; Paez, M. P. Absorcidn de Oxigeno por Disoluciones Acuosas de Cu(1). Influencia de la Temperatura. An. Quim. Ser. A 1984,80,284-288.
Charpentier, J. C. Mass Transfer Rates in Gas Liquid Absorbers and Reactors. In Advances in Chemical Engineering; Drew, T. B., Cokelet, G. R., Hoopes, J. W., Vermeulen, T., Eds.; Academic Press: New York, 1981;Vol. 11, Chapter 1. Danckwerts, P. S. Gas Liquid Reactions; McGraw-Hill: New York, 1970; pp 111-112. Gurol, M.; Nekouinaini, S. Kinetic behaviour of Ozone in Aqueous Solutions of Substituted Phenols. Znd. Eng. Chem. Fundam. 1984,23,54-60. Gurol, M.; Singer, P. C. Dynamics of Ozonation of Phenol. 11. Mathematical Simulation. Water Res. 1983,17, 1173-1181. Hikita, H.; Asai, S. Gas Absorption with (m,n)-th Order Irreversible Chemical Reaction. Znt. Chem. Eng. 1964,4,332-340. Hoign6, J. Mechanisms, Rates and Selectivities of Oxidations of Organic Compounds Initiated by Ozonation of Water. In Handbook of Ozone Technology and Applications; Rice, R. G., Netzer, A., Eds.; Ann Arbor Science: Ann Arbor, MI, 1982; Vol. 1, Chapter 12,pp 341-379. Hoign6, J.; Bader, H. The Role of Hydroxyl Radical Reactions in Ozonation Processes in Aqueous Solutions. Water Res. 1976,10, 377-386. Hoign6, J.; Bader, H. Rate Constants of Direct Reactions of Ozone with Organic and Inorganic Compounds in Water. 11. Dissociating Organic Compounds. Water Res. 1983, 17,184-194. Mehta, Y. M.; George, C. E.; Kuo, C. H. Mass Transfer and Selectivity of Ozone Reactions. Can. J. Chem. Eng. 1989,67,118-126. Singer, P. C.; Gurol, M. Dynamics of the Ozonation of Phenol. I. Experimental Observations. Water Res. 1983, 17, 1163-1171. Sotelo, J. L.; Beltrln, F. J.; Benitez, J.; BeltrHn-Heredia,J. Henry's Law Constant for the Ozone-Water System. Water Res. 1989,23, 1239-1246. Sotelo, J. L.; Beltrln, F. J.; Gonzalez, M. Ozonation of Aqueous Solutions of Resorcinol and Phloroglucinol. 1. Stoichiometryand Absorption Kinetic Regime. Znd. Eng. Chem. Res. 1990,29,2358. Van Krevelen, D. W.; Hoftijzer, P. J. Kinetics of Gas Liquid Reactions. Part I. General Theory. Recl. Trav. Chim. Pays-Bas 1948, 67, 563-586. Received for review December 26, 1989 Accepted July 30, 1990
Alkylation of Phenol with a-Methylstyrene, Propylene, Butenes, Isoamylene, 1-Octene, and Diisobutylene: Heterogeneous vs Homogeneous Catalysts Basab Chaudhuri and Man Mohan Sharma* Department of Chemical Technology, University of Bombay, Matunga, Bombay 400 019, India
The utility of a variety of catalysts, such as Amberlyst 15, Amberlyst XN1010, and Nafion NR50, clay catalysts Filtrol24 and Tonsil A/C, and homogeneous catalysts such as p-toluenesulfonic acid (p-TSA),was assessed in the monoalkylation of phenol with a-methylstyrene (AMS) in the temperature range 60-120 "C, and the ortho/para product distribution was compared. Olefins, such as propylene, 1-butene, isobutylene, isoamylene, and diisobutylene (DIB), were also used as alkylating a g e n t s for phenol with acidic catalyst to determine the ortho/para product distribution. The ortho/para alkylated product ratio can vary considerably for different olefins, between solid catalysts and homogeneous catalyst and also between macroporous cation-exchange resins Amberlyst 15 and partly Ag+-exchanged Amberlyst 15. Introduction
a d v a n t a g e s of ion-exchange resin catalysts are that they
The alkylation of phenol with olefins in the presence of acid catalyst to produce alkylphenols has been the subject of investigation b y m a n y research workers. Both homogeneous and heterogeneous (solid) catalysts have been used for the alkylation of phenols. Heterogeneous catalysts such as macroporous cation-exchange resins are preferred to homogeneous acid catalyst since t h e y can be easily separated from the reactant-product mixture. The other major
* To whom correspondence should be addressed. 0888-5885/91/2630-0227$02.50/0
eliminate undesirable side reactions and they eliminate corrosive environment that is often encountered w i t h homogeneous catalysts. The t h e r m o d y n a m i c s o r p t i o n or d i s t r i b u t i o n characteristics of the reactant and product between the bulk liquid and ion-exchange resin matrix may also play an i m p o r t a n t role and could possibly lead to results that are not achievable w i t h homogeneous acid catalysts. The alkylation reaction of phenol with a variety of olefins such as a-methylstyrene (AMS) and dissobutylene (DIB) and lower olefins such as propylene, 1-butene, iso-
63 1991 American Chemical Society
228 Ind. Eng. Chem. Res., Vol. 30, No. 1, 1991
butylene, and isoamylene are of industrial relevance and academic interest. p-tert-Butylphenol is used as a raw material for the production of a variety of resins by condensation with formaldehyde, which have outstanding properties in the manufacture of durable surface coatings, varnishes, wire enamels, printing inks, etc. p-tert-Amylphenol is used in the manufacture of surface-active agents, rubber chemicals, and petroleum additives. p-tertOctylphenol is used in the manufacture of oil-soluble phenol-formaldehyde resin. p-Cumylphenol [4-(1phenylethyl)phenol, PCP] is used for the production of resins, antioxidants, fungicides, printing inks, chemical modifiers for polycarbonates, etc. This work was undertaken to examine the performance of the macroporous ion-exchange resins Amberlyst 15 and Amberlyst XNlOlO in the alkylation of phenol with AMS and to map the best operating conditions for producing predominantly PCP, practically free of any dialkylated product. We also thought of studying the effect of the type of catalyst, olefin, and operating conditions on the ortho/para product distribution.
Previous Studies Published literature on the alkylation of phenol with AMS is scanty. Zieborak and co-workers (1982) have reported the synthesis of PCP in the presence of cationexchange resin Amberlyst 15. Macho et al. (1988) studied the reaction of phenol with a mixture of AMS and AMS dimers in the presence of active earth, polyphosphates, and zeolites in the temperature range 60-240 "C. These authors have claimed that the selectivity of phenol arylalkylation with AMS and its unsaturated dimers to 0- and p-cumylphenols is increased if AMS and AMS dimers are continuously or semicontinuously added to an excess of phenol, the mole ratio of AMS to phenol being 1:2-10. It appears from the foregoing reports that no systematic study on the alkylation of phenol with AMS in the presence of cation-exchange resins has been carried out. The ortho/para product distribution in the alkylation of phenol with olefins has been shown to vary with the nature of the olefin. a-Olefins such as 1-octene gave 3 times more ortho isomer than wm observed with propylene tetramer (Karavaev et al., 1967). Lysenko et al. (1974) studied the alkylation of phenol with isobutylene and butenes and observed that the yields of p-(CH3)3CC6H40H (from isobutylene) and p-MeCHEtC6H,0H (from butene) were 95.4% and 49.3% , respectively. Widdecke and Klein (1981) reported a ratio of 67:33 of ortho and para alkylated products in the alkylation of phenol with propylene in t,he presence of dry Amberlyst 15 at 98 "C. It was thought to be important to investigate the ortho/para product distribution in the alkylation of phenol with AMS and DIB in the presence of both homogeneous and heterogeneous catalysts (ion-exchangeresins, Ag+-exchangedion-exchange resin, and clay catalysts) and compare them with the ortho/para product distribution obtained in the reaction of phenol with lower olefins such as propylene, isobutylene, and isoamylene. Experimental Section Experiments were carried out in a 0.05-m-i.d., fully baffled, mechanically agitated reactor. A six-bladed glass disk turbine impeller was used for agitation. Some crucial experiments were also carried out in a 0.10-m-i.d., fully baffled, mechanically agitated reactor. AMS was ob,tained from Herdillia Chemicals LM. and was typically 95% pure; contaminants were close boiling tert-butylbenzene and cumene. All other chemicals were obtained from firms of
Table I. Properties of Ion-Exchange Resins Amberlyst DroDerties ;capacity of dry resin, mequiv/g '70 surface SOBHgroups internal surface area, m2/g porosity, vol '70 av pore diameter, A cross-linkage, %
~
~~
Amberlvst 15 4.5 4.4 50 36 265 20-25
XNlOlO 3.3 52.7 530 50 51 85
repute. The cation-exchange resin catalysts Amberlyst 15 and Amberlyst XNlOlO were obtained from Rohm and Haas Co.; the properties of the catalysts are listed in Table I. The gelular catalyst, Lewatit SC104, was obtained from Bayer. The catalysts were initially washed with deionized water and acetone to remove any impurity present on the external surface of the catalyst and then dehydrated under vacuum (1-2 mmHg) at a temperature of 100 "C (h2 "C) for 2-4 h to remove traces of moisture adsorbed on the catalyst surface. Some experiments were also carried out with Ag+-exchanged Amberlyst 15. The macroporous Amberlyst 15 beads were stirred with silver nitrate solution of known concentration to exchange around 50% H+with Ag+, and the Ag+-exchanged resins were subsequently dehydrated. All the experiments were carried out a t the desired temperature by placing the reactor in a constant temperature bath. The analysis of the reaction mixture consisting of unconverted olefin and olefin dimers, phenol, and alkylated products was done on a Perkin-Elmer 8500 gas chromatograph. A stainless steel column, OV-17 (10%) on Chromosorb WHP, was used for analysis, the length of which was 3.5 m. The initial oven temperature was kept at 100 "C for 120 s and was increased to 300 "C by programming at the rate of 0.25 "C/s. Some crucial analyses were done in a 4-m-long1 10% NPGA on Chromosorb WHP glass column. In all experiments, phenol and the cation-exchange resin were first taken in the reactor and heated to the reaction temperature while stirring. The olefin was then added to the reactor at the reaction temperature; the moment of addition of olefin into the reactor was taken as the starting time of the reaction. In gas-liquid reactions, the gas was continuously passed through the liquid-catalyst slurry so as to keep the liquid phase saturated with respect to the reacting olefin. Samples were withdrawn at regular intervals and analyzed. The same catalyst was used repeatedly, and the activity of the catalyst was checked from time to time by carrying out the reaction at a specified temperature and matching the conversion level.
Results and Discussion Alkylation of Phenol with AMs. The alkylation of phenol with AMS was studied in the temperature range 60-100 "C. The catalyst loading was varied in the range 1%-2% (wfw), and the mole ratio of phenol to AMS was 3:l. Cumene was used as diluent-solvent in the reaction. Ion-exchange resins such as Amberlyst 15, Amberlyst XN 1010, and Nafion H and clay catalysts such as Filtrol24 and Tonsil A/C were used for the alkylation of phenol with AMs. Homogeneous catalyst p-TSA was also employed for the alkylation reaction. The acid-catalyzed alkylation of phenol with AMS gave predominantly p-cumylphenol. The other alkylated products were o-cumylphenol (OCP) and dicumylphenol. The additional products formed in the reaction were unsaturated dimers of AMs, 2,4-diphenyl-4-methyl-l-pentene, 2,4-diphenyl-4-methyl-2-pentene, and the saturated
Ind. Eng. Chem. Res., Vol. 30, No. 1, 1991 229 Table 11. Synthesis of p-Cumylphenol: Product Distribution" % catalyst loading temp, "C catalyst (w/w) PCP 60 p-TSA 0.2 7.53 80 p-TSA 0.2 11.06 100 p-TSA 0.2 10.8 60 Amberlyst 15 1 12.84 80 Amberlyst 15 1 12.70 60 Amberlyst XNlOlO 1 8.55 80 Amberlyst XNlOlO 1 8.60 60 Lewatit SC104 1 8.73
OCP 1.02 2.0 2.04 0.23 0.35 0.95 0.95 0.25
product composition,6 mol % DCP A 1.37 0.2 0.34 0.3 0.33 0.26 0.03 0.22 1.09 0.06 1.00 1.08
B 2.01 0.55 0.60 0.32 0.29 1.87 1.84 0.20
C 0.13 0.17 0.19 0.62 0.80 0.14 0.17 0.50
OPhenol = 0.319 mol (47.2mol %); cumene = 0.25 mol (37mol %); AMS = 0.106 mol (15.7 mol %); reaction time = 60 min. bDCP = dicumylphenol; A = 2,4-diphenyl-4-methyI-l-pentene; B = 2,4-diphenyl-4-methyI-2-pentene; C = 1,1,3-trimethyl-3-phenylindan.
't I
r
Y~
1 2
0
R E A C T I O N T I M E (SEC I
Figure 1. Simultaneous series-parallel reactions occurring in the phenol + AMS system in the presence of acid catalyst.
Figure 2. Concentration profile of the reactant (AMS) and products in the synthesis of p-cumylphenol with 1%w/w Amberlyst 15 at 60 "C (phenol to AMS mole ratio = 3:1, diluent-cumene 42% w/w).
dimer 1,1,3-trimethyl-3-phenylindan. With fresh ion-exchange resins, the dimerization of AMS was found to be several times more effective than alkylation; the dimer then gradually decomposed to give the alkylated products. The tendency of AMS to dimerize decreased markedly with repeatedly used ion-exchange resin. The final products in the reaction of phenol with AMS were OCP,PCP, and the saturated dimer of AMs, 1,1,3-trimethyl-3phenylindan. The reaction scheme has been presented in Figure 1. There was no effect of the speed of agitation in the range 700-1600 rpm in the 0.05-m4.d. contactor on the alkylation of phenol with AMs. This proved that there was no external mass-transfer resistance associated with the alkylation of phenol with AMs. To assess whether any intraparticle gradient exists, the interruption test of Helfferich (1962) was performed. The catalyst particle size was also varied from 5 X lo-* to 2.5 X 10"' m (diameter) to find out the presence of intraparticle gradient. The aforementioned testa proved that there was no intraparticle gradient. The alkylation of phenol with AMS in the presence of cation-exchangeresin catalyst thus appears to be kinetically controlled. The effect of temperature on the alkylation of phenol with AMS was studied by varying the temperature from 60 to 100 "C. The reaction is characterized by low acti-
vation energy; with Amberlyst XNlOlO catalyst, the activation energy was estimated to be around 2.8 kcal/mol. Such a low activation energy in the solid-liquid reaction might suggest that the reaction was externally solid-liquid mass transfer (or pore diffusion) controlled and give disguised information regarding the controlling step of the reaction. To confirm the results and to find out the intrinsic activation energy of the alkylation of phenol with AMs, the effect of temperature was also studied with homogeneous p-TSA as the catalyst and an activation energy of 2.5 kcal/mol was obtained. The low activation energy in the alkylation of phenol with AMS could be compared with the activation energy of 2.23 kcal/mol in the reaction of phenol with cyclopentene in the presence of 98% sulfuric acid (Babin et al., 1985). The concentration profiles of the reactant and different products in the alkylation of phenol with AMS in the presence of Amberlyst 15 and Amberlyst XNlOlO are reported in Figures 2 and 3. The product distributions with homogeneous and heterogeneous catalysts a t different temperatures are given in Table 11. The homogeneous p-TSA catalyst gave a considerable amount of OCP and dicumylphenol in the product under otherwise uniform conditions. OCP and dicumylphenol were formed to a considerable extent with Amberlyst XNlOlO also. Both p-TSA and Amberlyst XNlOlO, however, gave very small
230 Ind. Eng. Chem. Res., Vol. 30, No. 1, 1991 Table 111. Ortho/Para Product Distribution in the Alkylation of Phenol with AMS in the Presence of Different Catalystsa product distribution, % w/w % catalyst loading alkylated unsaturated saturated ortholpara catalyst (w/w) products dimers dimer ratio p-TSA 0.20 97 2.0 1.0 16:84 2.5 97 2.0 1.0 1090 Amberlyst XNlOlO 2.5 97 1.7 1.3 3:97 Amberlyst 15 1.4:98.6 2.5 46 6.0 48.0 Filtrol 24 5.0 90 7.0 3.0 1.3:98.7 Nafion NR50 0.599.5 2.5 30 3.0 67.0 Tonsil A/C 11:89 15.0 80 5.0 15.0 AIC13
OReaction temperature = 60 "C; mole ratio of phenol to AMS = 3:l;solvent = cumene; semibatch mode of addition of AMs; matching conversion level = 95% (with respect to AMS).
1
a
1
14
2
0
0 REACTION T I M E
ISECI
Figure 3. Concentration profile of the reactant (AMs)and products in the synthesis of p-cumylphenol with 1% w/w Amberlyst XNlOlO a t 60 "C (phenol to AMS mole ratio = 3:1,diluent-cumene 42% w/w).
quantities of indanic dimer in the product compared to Amberlyst 15. The product distribution suggests that catalysis by p-TSA and Amberlyst XNlOlO is very similar in nature and different from that exhibited by Amberlyst 15. Elevated temperatures favored the formation of OCP and dicumylphenol in the presence of p-TSA and Amberlyst XNlOlO catalysts and the saturated indanic dimer in the presence of Amberlyst 15. Thus, the optimum temperature for the alkylation of phenol with AMS in the presence of ion-exchange resin catalysts was found to be between 60 and 70 "C. The use of cumene as solvent in the reaction medium gave a cleaner alkylated product. When pure phenol was alkylated with AMS in the presence of Amberlyst 15, the rate of formation of the saturated indanic dimer increased markedly; dicumylphenol was also formed. The faster dimerization of AMS to the saturated indanic dimer in polar phenol medium might be due to the favorable partitioning of AMS for the resin phase. The optimum mole ratio of phenol to AMS (in cumene) was found to be 3:l for PCP formation (free of any dialkylated product). When undiluted phenol is alkylated, the mole ratio of phenol to AMS should be higher, preferably 4:1, for PCP formation (free of dialkylated product). The use of a small amount of isopropyl alcohol in the reaction medium was tried as a strategy for suppressing the dimerization of AMs. This, however, did not give any improvement and the rate of alkylation dropped drastically
in the presence of isopropyl alcohol. Macroporous ion-exchange resin Amberlyst 15 was found to give better quality PCP, practically free of any dicumylphenol, a t moderate temperatures and a t a phenol to AMS mole ratio of 3:l. The rates of alkylation were higher with Amberlyst 15 than those achieved with Amberlyst XN 1010, under otherwise identical conditions. The fraction of surface sulfonic acid groups in Amberlyst XNlOlO is 10 times higher than that in Amberlyst 15 (Table I). If the reaction took place on the pore surface of gelular microspheres, the rate should have been approximately 10 times higher with Amberlyst XN1010. The high rates of reaction realized with Amberlyst 15 indicate that the sulfonic acid groups in the gelular microspheres in Amberlyst 15 participate in the reaction. The Hammett acidity of the gelular sulfonic acid groups is higher than that of the surface sulfonic acid groups; hence, Amberlyst 15 is catalytically more active than Amberlyst XNlOlO for the alkylation of phenol with AMs. p-Cumylphenol of over 98% purity could be obtained upon distillation of the reaction mixture containing cumene, phenol, and PCP (under 20 mmHg pressure). A higher purity PCP of 99.2% could be obtained by crystallization of PCP from its solution in n-heptane; OCP is more soluble in n-heptane than PCP. The ortho/para product distribution (positional selectivity) in the alkylation of phenol with AMS was determined with a variety of catalysts, and the results are given in Table 111. In all the experiments, AMS was added quanta by quanta into the cumene-phenol-catalyst slurry at a temperature of 60 "C over a period of 2-3 h, and the reaction mixture was subsequently stirred for an additional hour. It was observed that the homogeneous catalyst gives a higher ortho alkylated product as compared to ion-exchange resins or clay catalysts. The highest PCP to OCP ratio of 99.5:0.5 was obtained with dehydrated clay catalyst Tonsil A/C. The dehydrated clay catalysts, Filtrol24 and Tonsil A/C, gave, however, a large quantity of the saturated indanic dimer in the product. It was also observed that the rate of alkylation of phenol with AMS was very low with undehydrated clays in the temperature range 60-80 "C, and the dimerization of AMS was the major reaction. The alkylation of phenol containing 5% (w/w) water was carried out with AMS in the presence of both the gelular Lewatit SC104 and the macroreticular Amberlyet 15 a t a temperature of 60 "C; the catalyst loading was 5% (w/w). With water-swollen catalyst, the ortho/para alkylated product ratio was 991 with both Lewatit SC104 and Amberlyst 15 catalysts as compared to 3:97 with dry catalysts. The presence of water in phenol thus promotes ortho alkylation, and to maximize the yield of PCP (defined as percent PCP in the alkylated products formed) in the alkylation of phenol with AMs, anhydrous phenol should be used.
Ind. Eng. Chem. Res., Vol. 30, No. 1, 1991 231 Table IV. Comparison of Ortho/Para Product Distribution in the Alkylation of Phenol with AMs, DIB, and I-Octene i n Homogeneous, Solid-Liquid Heterogeneous Modes" converortho/ catalvst olefin sion, % Dara ratio 40 1684 p-TSA AMS 40 3:97 AMS Amberlyst 15 25 5:95 Ag+-exchanged Amberlyst 15 AMS 41:59 40 p-TSA DIB 40 5:95 DIB Amberlyst 15 20:80 8 Ag+-exchanged Amberlyst 15 DIB 72:28 p-TSA 1-octene 20 5941 1-octene 20 Amberlyst 15 5 80:20 Ag+-exchanged Amberlyst 15 1-octene 'Reaction temperature for AMS and DIB = 70 OC; reaction temperature for 1-octene = 90 'C; phenol to olefin mole ratio = 4:l. Table V. Ortho/Para Product Distribution in the Alkylation of Phenol with Different Olefins in the Presence of Amberlyst 15" catalyst loading, ortho/ olefin temp, "C 70 w/w conversion levelb para ratio propylene 80 5 20 66:33 6633 80 5 20 1-butene 80 5 20 3070 isobutylene 595 120 5 20 isobutylene 49:51 isoamylene 60 5 10 100 5 10 5:95 isoamylene 5:95 80 2 70 diisobutylene 80 1 a t all conversions 3:97 AMS "Mole ratio of phenol to liquid olefin in all cases = 4:l. *For gaseous olefins and for isoamylene (quanta by quanta addition with this olefin), conversion level indicates conversion with respect to phenol; for other olefins, conversion level indicates conversion with respect to olefin.
The comparison of ortho/para product distribution in the alkylation of phenol with AMS, DIB, and 1-octene under different operating conditions is given in Table IV. With homogeneous p-TSA catalyst, the ortho alkylated product can be produced to a greater extent compared to the heterogeneous ion-exchange resin catalyst. Ag+-exchanged Amberlyst 15 was also found to give more ortho alkylated product. The reasons for higher ortho alkylated product formation with Ag+-exchanged cation-exchange resin are not clear. It is likely that the olefin-Ag+ complex allows suitable orientation for more selective ortho alkylation to occur. The olefins, such as propylene, 1-butene, isobutylene, and isoamylene, were also used as alkylating agents in the alkylation of phenol in the presence of Amberlyst 15 catalyst to find out the ortho/para product distribution. The results are summarized in Table V. In the alkylation of phenol with olefins such as propylene and 1-butene which give secondary carbocations, the ortho alkylation was predominant even a t elevated temperatures. In the case of isobutylene and isoamylene, which give tertiary carbocations, a fairly high ratio of ortho/para alkylated product was initially obtained which dropped substantially with an increase in the temperature due to the isomerization of the ortho alkylated product to the para alkylated product. The high ratio of para to ortho alkylated products in the alkylation of phenol with AMS in the temperature range 50-120 "C was perhaps due to the typical structure of the carbocation, derived from AMS, which did not
readily give ortho alkylation. The ion-exchange resin matrix also exhibits shape selectivity and favors para alkylation as the experimental results suggest. At elevated temperatures (100-120 "C), OCP was found to isomerize to PCP a t a very slow rate. It was also observed that o-isopropylphenol did not isomerize to p-isopropylphenol even on prolonged stirring with the catalyst in the temperature range 90-100 "C. Conclusions Macroreticular cation-exchange resin Amberlyst 15 was found to be the most useful catalyst amongst t h m studied, in the alkylation of phenol with AMS. The use of cumene as solvent in the synthesis of PCP was found to be important since undiluted phenol, when alkylated with AMS, gave a considerable amount of the saturated dimer of AMS, 1,1,3-trimethyl-3-phenylindan, and the dialkylated product. For the selective production of p-cumylphenol, the reaction temperature should be between 60 and 70 "C. The ortho/para product distribution in the alkylation of phenol with olefin was found to be a function of catalyst, reaction temperature, and nature of the reacting olefin. Ag+-exchanged Amberlyst 15 promoted ortho alkylation in the alkylation of phenol with olefins such as DIB and 1-octene. Acknowledgment
B.C.is thankful to the University Grants Commission, New Delhi, for the award of Senior Research Fellowship. Registry No. PCP,599-64-4;OCP,18168-4016;DCP,6781364-3;pTSA, 104-15-4;AMs, 98-83-9;DIB, 25167-70-8;AlC19, 7446-70-0;Ag+, 7440-22-4;Lewatit SC104,68247-92-7; Amberlyst XN1010, 54991-00-3;Amberlyst 15, 9037-24-5;Filtrol 24, Tonsil A/C, 123205-63-0; 123205-60-7;Nafion NR50,118473-68-0; 2,4-diphenyl-4-methyl-l-pentene, 6362-80-7;2,4-diphenyl-4methyl-2-pentene, 6258-73-7;1,1,3-trimethyl-3-phenylindan, 3910-35-8;1-octene, 111-66-0;propylene, 115-07-1;1-butene, 106-98-9;isobutylene, 115-11-7;isoamylene, 26760-64-5;cumene, 98-82-8;water, 7732-18-5;phenol, 108-95-2.
Literature Cited Babin, E. P.; Dzhafarova, N. A.; Farzaliev, Y. M.; Allakhverdiev, M. A. Certain kinetic relationship of cycloalkylation of phenol and its homologs. Zh. Prikl. Khim. 1985, 58 (2),424-427. Helfferich, F. Kinetics. Ion Exchange; McGraw-Hill: New York, 1962;pp 256-257. Karavaev, N. M.;Dmitriev, S. A.; Zimina, K. I.; Kazakov, E. I.; Korenev, K. D.; Kotova, G. G.; Tsvetkov, 0. N. Ortho effect in phenol alkylation. Dokl. Akad. Nauk SSSR 1967,173 (4), 832833;Chem. Abstr. 1967,67, 21540. Lysenko, A. P.;Yakunina, G. I.; Zelentsova, M. I. Isomer Composition of butylphenols during alkylation of phenol by butenes in the presence of hydrogenfluoride. Tr. Inst. Khim., U r d Nauctin. Tsentr. Akad. Nauk SSSR 1974,244552; Chem. Abstr. 1975, 83, 27778. Macho, V.; Jurecek, L.; Adam, V.; Kavala, M.; Jurecekova, E.; Hlinstak, K.; Mikula, 0.; Storecko, J.; Schwaraz, F.; Varga, M. Czech. CS 245,895,1987;Chem. Abstr. 1988, 109, 112426. Widdecke, H.; Klein, J. Die alkylierung von phenol mit gasiformign olefin an polymeren festsauren. Chem.-Ing.-Tech. 1981, 53, 94-97. Zieborak, 2.;Rutajezak, W.; Kowalska, H. Synthesis of p-cumylphenol in the presence of a cation exchanger as a catalyst. Chem. Stosowana. 1982,3-4, 341-349. Received for review December 28, 1989 Revised manuscript receioed July 2, 1990 Accepted July 11, 1990
