Aluminum Phosphate Catalyst Howard E. Sheffer,' Robert 1, Perry: Raymond J. Thimineur; Beverly T. Adams,4 John 1. S i r n ~ n i a nNathan ,~ 1. Z u t t ~ and ,~ Robert A. Clendennings Chemistry Department, Union College, Schenectady, N.Y. 12308, and V7. H. Wright Research Center, Schenectady Chemicals, Inc., Schenectady, N.Y. 12309
Phenol is alkylated with methyl, ethyl, and sec-butyl alcohols at temperatures ranging from 285-485OC with an aluminum phosphate catalyst on alumina support. By use of a fixed-bed catalyst and space times of 2-4 sec, phenol is converted to alkyl phenols and phenolic ethers in good yields. Some indication of the effective life and reactivation of the catalyst is given. Optically active sec-butyl alcohol gives optically inactive products.
w i t h an aluminum phosphate catalyst, from 44-66% of the phenol feed is converted with alcohols to alkyl phenols and phenolic ethers (Table I). This catalyst is the most effective of a series of over one hundred catalysts studied previously (Sheffer, 1945). The striking activity of this catalyst is demonstrated by observing that the alumina support alone gives only 3% conversion of phenol t o phenetole by ethyl alcohol, whereas aluminum phosphate catalyst produces 20-30y0 ethyl phenols. In all these alkylations, the three isomeric monoalkyl phenols are obtained, as well as higher boiling phenols and a high boiling residue. These conversions of phenol to cresols by methanol or t o ethyl phenols by ethanol are especially good since it is much easier to introduce higher alkyl groups than methyl or ethyl groups in the alkylation of phenols. Previous attempts to alkylate phenol have involved batch operation b y use of long contact times. Boric acid-oxalic acid catalyst provides excellent yields of p-tert-butyl phenol from phenol and diisobutylene in 15 min at 135°C (Bakelite, 1944). Phenol is alkylated with methanol, ethanol, and isobutyl alcohol b y use of phosphoric acid-silica and -alumina catalysts (Ohta, 1948). A sulfonated styrene-divinyl benzene copolymer catalyst provides p-tert-butyl phenol in 8 hr at 100°C from phenol and isobutylene (D'Xlelio, 1957). The isobutyl alcohol-boron trifluoride complex gives 80% p-tert-butyl phenol in 1-3 hr at 120-170°C (Romadane and Stipnieks, 1960). An alumina silicate catalyst at 210230°C yields 95% total conversion of phenol by isopropyl alcohol a t a space velocity of 0.2 hr-1 (Turova-Polyak and Rudenko, 1960). Refluxing phenol and sec-butyl alcohol for 1.5 hr over an ion exchange resin produces 95% p-tert-butyl phenol (Belov, 1962). 7-Alumina activated at 450°C affords
good yields of alkyl phenols from phenol and olefiiis at 250350°C at 30-200 a t m (Hahn, 1963). Nonyl phenol is obtained in 83y0 yield by reacting phenol Kith propylene trimer at 178°C for 24 hr with a cation exchange resin (Mixer and Wagner, 1963). h number of crystalline alumina silicates are described a s catalysts for alkylation (Venuto et al., 1966). Phenol is methylated a t 400°C in high yields with mordenite as catalyst, but the contact times are long (Socony Blobil, 1966). A long contact time is also used t o methylate phenol with aluminum oxide a t 300-350" C (Union Rheinische Braunkohlen Kraftstoff, 1966). By continually removing water, phenol is alkylated in the liquid phase over silica-alumina (heated for 2 h r a t 550°C) to produce in 60-70y0 yields p-tert-butyl phenol a t 150-70°C (Ryabov and Golodnaya, 1966). X catalyst prepared from diatomaceous earth and molten HeP4018 provides excellent yields of alkyl phenols from diisobutylene and phenol in 10-15 min a t 100°C (Rybar et al., 1966). By use of a contact time of 10 sec, o-cresol is obtained in 27% yield from phenol and methanol over activated alumina a t 285-9OoC (Boiidy et al., 1967). Gumbrin clay treated with dry hydrogen chloride gives only 10% yield of p-tert-butyl phenol in 1 h r a t 70-80°C from phenol and isobutyl alcohol (Radzevenchuh and Kaplan, 1959). I n some related studies t h e alkylation of benzene by optically active sec-butyl alcohol gives
