Patented Mar. 17, 1953 2,632,026 UNITED STATES PATENT OFFICE 2,632,026 OXDATION OFAROMATIC HYDROCARBONS Joshua C. Conner, Jr., Wilmington, Dei, assignor to Hercules Powder Company, Wilmington, Dei, a corporation of Delaware No Drawing. Application February 18, 1950, Serial No. 145,091 9 Cairms. (C. 260-610) 1. 2 This invention relates to a process for oxidizing of cumene at a temperature in excess of 20° C. an alkyl-substituted aromatic organic compound while simultaneously passing a stream of an having the structural formula, Oxygen-containing gas containing gaseous am Rt H monia, in catalytic amounts through the reac N / tion mixture. The reaction is continued until standard analytical data, such as refractive in R / Air dex, indicate the conversion of from about 10% to about 70% of the original cumene to oxygen in which R1 and R2 represent alkyl groups and ated products. The reaction mixture may then Ar represents either an aryl group or an alkaryl 0. be treated in accordance with known techniques group. More particularly, the invention relates to obtain a product containing preponderant to a process for the oxidation of compounds Such amounts of a,c-dimethylbenzyl hydroperoxide. as cumene in the liquid phase by naeans of no Having thus described the invention, the foll lecular. Oxygen. lowing examples are specific embodiments there It is known that cunene, for example, may be 5 of. All parts are parts by weight unless otherwise oxidized in the liquid phase by means of molec indicated. ular oxygen, but none of the processes hereto EXAMPLE 1. fore disclosed for the oxidation of cumene have resulted in substantial yields of a,c-dimethyl A glass reaction vessel equipped with a reflux benzyl hydroperoxide. Under the conditions condenser, a high Speed Stirrer and an Oxygen practiced in prior procedures, difficulties are en 2) inlet was charged With 400 parts of cunene. countered in initiating the reaction and the a,c- Twelve and three-tenths parts of oxidized cul dimethylbenzyl hydroperoxide has not been ob mene containing 97.8% of aa-dinnethylbenzyl hy tained in substantial yields as the major product droperoxide was added to the charge as a reac by the oxidation of cumene. The oxidation has, tion initiator. Oxygen containing 0.26% gaseous instead, led to mixtures containing preponderant ammonia was passed through the reaction mix amounts of acetophenone and Sinall amounts of ture at the rate of 15 liters per hour per kilo aa-dimethylbenzyl alcohol. gran of cumene. A temperature of 90° C. Was Now in accordance with this invention, it has maintained throughout the reaction period, been discovered that tertiary hydroperoxides Which extended for 51.0 hours. Table I shows having the structural formula 30 the data for the oxidation. R OOH Table I DoC Oxidation Prod R Yar ucts in Product 35 . Rate of may be prepared by contacting an alkyl-substi - (Percent) Oxidatiation tuted aromatic organic compound having the Time (Hr.) no - (Pigent? structural formula previously described in the Hydro- T. liquid phase at a temperature in excess of 20° C. Total befoxiie with an oxygen-containing gas in the presence 40 20.6.--- 15.7 14.8 0.62 of gaseous ammonia, the ammonia, acting cata 28.7 20.5 19.6 0.61 44.6- 27.4 26.9 0, 55 lytically as an initiator for the reaction. In the structural formula of the hydroperoxides, R1 and 5-0------------- ...! .. 5002 30.0 28.9 0.53 R2 represent alkyl groups which may be either the same or different and Ar represents a Sub During the oxidation the effluent OXygen gaS COI)- stituent selected from the group consisting of tained a substantial amount of ammonia. Upon aryl and alkalyl groups. These tertiary hydro completion of the oxidation, the pH determined peroxides may be referred to as a,a-dialkylaryl on distilled water after shaking with the organic methyl hydroperoxides or, if desired, as aryl phase was 9.3 showing the presence of excess (dialkyl)methyl hydroperoxides. Thus, the hy ammonia, and the crude amber reaction product droperoxide derived from cunene in accordance amounted to 350 parts. Analysis of the reaction with the process of this invention may be nained product indicated the presence of 28.9% a,c- a,a-dimethylbenzyl hydroperoxide, or, if desired, dimethylbenzyl hydroperoxide, 70% unreacted phenyl (dimethyl)methyl hydroperoxide. cumene, 0.90% ca,a-dimethylbenzyl alcohol, and The process of this invention may be practiced, {0.22% acetophenone. Based on the amount of for example, by vigorously agitating a mixture the aa-dimethylbenzyl hydroperoxide initiator 2,632,026 3 4. and the amount of each of the reaction products taining a,c-dimethylbenzyl hydroperoxide was expressed in terms of cumene, the recovery of Withdrawn through a valve at the bottom of the the components making up the reaction product tower adjacent the air inlet. A sample taken at amounted to 90.6%. The yield of a,c-dimethyl the end of 16 hours after the continuous with benzyl hydroperoxide was 95.5% of the theoreti drawal of product had continued 8 hours showed cal amount based on the cumene, taking into 26.8% a,a-dimethylbenzyl hydroperoxide. Dur consideration that the conversion at 51.0 hours ing this period the ammonia, content of the air WaS 30.0%. The conversion of 30.0% represents entering the tower was 1.24% by volume and that Conversion to total oxygenated products. of the air leaving the tower was 0.78% by volume. O During the next 8-hour period the cumene flow EXAMPLE 2 rate was 7.2 lb. per hour and the ammonia con The same equipment and the same conditions tent of the air entering the tower was 1.06% by of temperature and oxygen flow as those de Volurne While that leaving the tower was 0.29% Scribed in Example 1 were again utilized. In by volume. The rate of air flow was 0.7-1.0 cu. this case, however, the oxygen contained 1% ft. per minute as in the previous periods. At ga-SeOS annonia. At the end of 22.8 hours of the end of this 8-hour period the product being reaction, a Sample of the oxidized product had Withdrawn at the same rate as the cumene being a refractive index at 20° C. of 1.4945, thus indi introduced analyzed 23.1% a,a-dimethylbenzyl Cating a conversion of the cumene to 12.0% oxy hydroperoxide. Further analysis of this prod genated products. The per cent a,c-dimethyl uct ShoWed that a,c-dimethylbenzyl hydroperox benzyl hydroperoxide at this time was 11.4%. ide constituted 89.1% of the total oxidation prod At the end of 44.8 hours the reaction was termi ucts in the crude product. nated. At this time the refractive index of the During the next 8-hour period the cunene flow. reaction product was 1.4981, thus indicating a rate averaged 6.5 lb. per hour, the air flow rate total conversion of 24.6% and the hydroperoxide Varied from 0.7 to 1.0 cu. ft. per minute and the content was 24.0. The pH determined on dis annonia, content of the air entering the tower tilled Water after shaking with the organic phase Was about 0.83% by volune, While that of the air Was 8.6. Analysis of the reaction product indi leaving the tower was about 0.30% by volume. cated that a yield of 97.1% of a,a-dimethylbenzy. The a,c-dimethylbenzyl hydroperoxide content of hydroperoxide had been obtained based on the 30 the product continuously being withdrawn av Cunene utilized and the percentage total con eraged 23.7%. version. Calculations showed that the per cent The examples have set forth the use of cumene recovery was 96.2. The product also contained and p-cymene as compounds which may be 0.47% a,a-dimethylbenzyl alcohol and 0.11% acetophenone. treated in accordance with the process of this 3 invention. Other compounds, however, having EXAMPLE 3 the structural formula previously set forth Such The same equipment and the same conditions as diisopropylbenzene may be utilized. The pri of temperature and oxygen input as those de nary requirement for compounds which may be Scribed in Example 1 were again utilized. In this Oxidized in accordance With this invention is the case, however, p-cymene was oxidized, the presence of a tertiary carbon atom, the fourth amount of this compound charged to the reactor valence bond of which is satisfied by a hydrogen being 400 parts. At the beginning of the oxida aton. AS indicated by the structural formula, tion the mixture also was charged with 17.5 the carbon atom is tertiary because it is directly parts of oxidized cymene containing 68.4% ag connected to three other carbon atoms One of dimethyl-p-methylbenzyl hydroperoxide as ini i. which is contained in each of the groups repre tiator. The oxidation reaction was carried out Sented by R1 and E2 and Ar. as in Example 1 and continued for 47.9 hours. The aryl or alkaryl group need not be derived At the end of this time the reaction product from benzene as in the case of Cunene, p-cymene, Showed a content of 15.7% a,a-dimethyl-p-meth and p-diisopropylbenzene. Other compounds ylbenzyl hydroperoxide, 1.51% a,c-dimethyl-p- containing aromatic nuclei, Such as those derived nethylbenzyl alcohol, and 0.66% p-methyl aceto from naphthalene, anthracene, and phenan phenone. threne, which otherwise meet the requirements of the structural formula, are also operable.