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J. Org. Chem. 1984, 49, 1603-1607
2-phenylthiophene, 825-55-8; 2-phenylpyridine, 1008-89-5; 32974-90-5; 4-C1C,&C&-2’-OMe, 53824-23-0; 4-C1C&C&-3’-OMe, 66175-36-8; ~ - C ~ C O H ~ C ~ H ~phenylpyridine, 1008-88-4; 4-phenylpyridine, 939-23-1; 2-(3fluorophenyl)pyridine, 58861-54-4; 3-(3-fluorophenyl)pyridine, 4’-OMe, 58970-19-7; 3,4-Clzc6H3Ph,2974-92-7; 4-BrC6H4C6H32‘,5’-Mez, 89346-51-0; 4-BrC6H4C6Hz-2’,4’,6’-Me3, 20434-38-2; 79412-32-1; 4-(3-fluorophenyl)pyridme,39795-59-0; 2-phenylfuran, 17221-37-3; 2-(4-~hlorophenyl)thiophene,40133-23-1; 2-(42-MeC6H4Ph,643-58-3; 3-MeC6H4Ph,643-93-6; 4-MeC6H4Ph, 644-08-6;4-MeC6H4C6H4-2’-Me, 611-61-0;4-MeC6H4C6H4-3’-Me, chlorophenyl)pyridine, 5969-83-5; 3-(4-~hlorophenyl)pyridine, 7383-90-6; 4-MeC6H4C6H4-4’-Me, 613-33-2;Ph(CH2)zPh,103-29-7; 5957-97-1; 4-(4-chlorophenyl)pyridine,5957-96-0; 2-(4-bromo3,4-Me2C6H3Ph,4433-11-8; 3,4-Me2C6H3C6H4-2’-F, 89346-52-1; phenyl)furan, 14297-34-8;2-(4-bromophenyl)thiophene, 4013322-0; lH-indazole, 271-44-3;2-(4-methylphenyl)furan,17113-32-5; 3,4-MezC6H3C6H4-3’-F,89346-53-2; 3,4-MezC6H3C6H4-4’-F, 72968-91-3;4-EtC6H4Ph,5707-44-8; 3,5-(Me0)2C6H3Ph,643262-(4-methylphenyl)pyridine, 4467-06-5; 3-(4-methylphenyl)pyridine, 4423-09-0; 4-(4-methylphenyl)pyridine,4423-10-3; 217-6; 2-O2NCsH4Ph, 86-00-0; 4-OzNC,H,Ph, 92-93-3; 2OZNC6H,CH=CHPh, 4714-25-4; PhCH2PCPh3C1-, 1100-88-5; (4-nitrophenyl)furan, 28123-72-0; 2-(4-nitrophenyl)thiophene, 2-O2NC6H,CHO, 552-89-6; PhCH=CHCHZCl, 2687-12-9; PhSP, 59156-21-7; 3,4-(methylenedioxy)benzenediazonium tetrafluoroborate, 1682-37-7;fluorenone, 486-25-9;phenanthrene-9-carboxylic 603-35-0; 2-02NC6H4C1, 88-73-3; PhS-K’, 3111-52-2; PhO(CHZCHzO),Ph, 20768-77-8; 2-02NC6H40(CH&H20)4Ph, acid, 837-45-6;dibenzo[a,c]cyclooctane,1082-12-8; 3-(3-phenyl89346-79-2;4-0zNC6H4O(CHzCHz0)4Ph,89346-80-5; HO(CH2Cpropyl)-1H-indazole, 89346-77-0; dibenzofuran, 132-64-9; diH,O),H, 112-60-7; PhCHzCl, 100-44-7; K+-0zC(CH2)4CH3, benzothiophene, 132-65-0; 1,4,7,10,13-pentaoxa-14,15:16,17-di19455-00-6; K+-OZC(CH2)14CH3, 2624-31-9; CHSCN, 75-05-8; benzocycloheptadecane, 89346-74-7; 2,5,8,11,14-pentaoxaKOAc, 127-08-2; NaOAc, 127-09-3; KOz, 12030-88-5; KZCO3, 15,16:17,18-dibenzocyclooctadecan-l-one, 89346-75-8;2-[2-[2-(2584-08-7;thiophene, 110-02-1;pyridine, 110-86-1;furan, 110-00-9; benzoyloxyethoxy)ethoxy]ethoxy]ethoxybenzene, 89346-76-9.
Aromatic Acetonylation Promoted by Manganese(II1) and Cerium(1V) Salts’ Michael E. Kurz,* Vijayalakshmi Baru, and P-Nhi Nguyen Department of Chemistry, Illinois State University, Normal, Illinois 61 761
Received June 14, 1983 Treatment of aromatic hydrocarbons with acetone and manganese(II1) acetate gave rise to arylacetones in yields ranging from 25% with chlorobenzene to 74% with anisole. Cerium(1V) salts were also successfully used as promoters but gave lower yields. The reactions were relatively free of side products except with toluene. Isomer distributions, relative rates, and partial rate factors were determined for acetonylation of anisole, toluene, chlorobenzene, and fluorobenzene. A Hammett plot of the log of the partial rate factors for the manganese(II1) system vs. u-constants gave a slope, p , of -2.4 f 0.3. An isotope effect kH/kD = 3.8 was observed for the manganese(II1)-promoted reaction with acetone-d6,indicating rate-determining proton loss from acetone. The overall mechanism involves formation and attack of acetonyl radicals onto the aromatic hydrocarbon followed by subsequent oxidative deprotonation of the resulting u-radical complex. The acetonyl radical exhibits appreciable electron-deficient character in its substitution behavior with aromatic hydrocarbons.
Metal ion promoted oxidative deprotonation methods have been used to generate such carbon radicals as the ~arboxymethyl,~*~ a ~ e t o n y l ?and ~ nitromethyP8 (eq l).9 CH3X
Mn(II1) or
CH2X +H+
+
ArH
X = COZH, COCH3, NO2 When produced in the presence of suitable alkenes, quite a number of interesting processes have been reported,2-5J+12most resulting from initial attack of the carbon (1) Taken in part from the M.S. dissertation of V. Baru, Illinois State University, Normal, IL, 1982. (2) Heiba, E. I.; Dessau, R. M.; Rodewald, P. G. J. Am. Chem. SOC. 1974, 96,7977. (3) Okano, M. Chem. Znd. 1972, 423. (4) Heiba, E. I.; Dessau, R. M. J. Am. Chem. SOC.1971, 93, 524. (5) Vinogradov, M. G.; Venenchikov, S. P.; Fedora, T. M.; Nikishin, G. I. J . Org. Chem. (USSR) 1975,11,937. (6) Kurz, M. E.; Chen, R. T. Y. J. Org. Chem. 1978, 43, 239. (7) Kurz, M. E.; Ngoviwatchai, P.; Tantrarat, T. J. Org. Chem. 1981, 46, 4668. (8) Kurz, M. E.; Ngoviwatchai, P. J. Org. Chem. 1981, 46, 4672. (9) Kochi, J. K. “Organometallic Mechanisms and Catalysis”; Academic Press: New York, 1978; p 93. (10) Heiba, E. I.; Dessau, R. M. J. Am. Chem. SOC.1972, 94, 2888. (11) Vinogradov, M. G.; Petrenko, 0. N.; Verenchikov, S. P.; Nikishin, G. I. J. Org. Chem. (USSR) 1980, 16, 714. (12) Kurz, M. E.; Reif, L.; Tantrarat, T. J. Org. Chem. 1983,48, 1373.
0022-3263/84/1949-1603$01.50/0
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radical onto the r-bond (eq 2). The analogous radical RCH=CHR C H 2 X RCHC(R)HCH,X (2) generation with aromatic hydrocarbons present has led to aromatic substitution (eq 3), the mechanism of which has
+ CH3X
Mn(II1) or
ArCHzX
(3)
been studied rather extensively for carboxymethylation2 and nitromethylation.6-8 However, the aromatic acetonylation has been described only b r i e f l ~ . ~ ,The ’ ~ purpose of this work was to more thoroughly study the metal ion promoted aromatic acetonylation with an eye toward assessing the polar properties of the acetonyl radical involved.
Experimental Section Instrumentation. GC analyses were done on a HewlettPackard Model 5840A gas chromatograph equipped with a flame ionization detector and capillary inlet system (split mode). The capillary columns used were (1) 30 m X 0.22 mm sp 2100 glass, (2) 10 m X 0.22 mm sp 2100 glass, (3) 10 m X 0.22 mm Carbowax 20 M fused silica, and (4) 30 m X 0.22 mm bonded SE-30 fused (13) Min, R. S.; Aksenov, V. S.; Vinogradov, M. G.; Nikishin, G. I. Izu. Akad. Nauk SSSR, Ser. Khim. 1979, 2292; Chem. Abstr. 1980, 92, 110239s.
0 1984 American Chemical Society
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J. Org. Chem., Vol. 49, No. 9, 1984
silica column. Preparative GC was done on a Varian Aerograph Model 90-P gas chromatograph equipped with a 6 ft X 0.25 in. SS, 15% SE-30 on 80/100 Chromosorb W column. IR spectra were obtained with a Perkin-Elmer Model 710B spectrophotometer as thin films between sodium chloride discs or as solutions in chloroform-d using 0.1-mm sodium chloride matched cavity cells. NMR spectra were obtained with a 60-MHz Hitachi Perkin-Elmer Model R-24 B spectrophotometer, using chloroform-d solvent containing 1% Me,Si. Elemental analyses were performed by Micro Analysis Inc. Manganese(II1) acetate was prepared according to a literature methodeJ4 and analyzed for purity by iodometry. Cerium(1V) acetate was prepared from ozonolysis of cerium(II1) salts in acetic acid15and was used without isolation.* Cerium(II1) ammonium nitrate was commercially available in high purity. The aromatic hydrocarbons and solvents (AR grade) were checked by GC and used as received. Acetone-d6 (Aldrich) was found to contain
