THE FRIES REACTION. The Rearrangement of the Esters of Dihydric Phenols

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1 Part II. THE FRIES REACTION The Rearrangement of the Esters of Dihydric Phenols BY R. D. DESAI, F.A.Sc. AND C. K. MAVANI (From the Department of Chemical Technology and the Chemlatry Departmen& St. Xavler's Coilege, Bombay 1) Recr Or 21, 1948 AS stated in Part I of this series, the Fries Reaction had not been as systematicauy studied with regard to the esters of dihydrie phenols as in the case of mono-hydrie phenois. Thus the esters of catechol had been shown to undergo this reaction by Rosenmund and Lohfert z and Miller, Harting, Rock and Crossley 2 and conditions for the br yield of 4-acyl-defivatives had been worked out. The esters of resorcinol had been studied by Rosenmund and eo-workers, Baker, 4 Venkataraman and Gulati, 5 Klarmann, e and Mauthner, 7 but the results vary, while in the case of orcinol, only one ester had been studied in this respect by Mauthner (loc. cit.). HydroquŸ diacetate was reported by Rosenmund and Lohfert (loc. cit.) to give the 2-acyl-derivative but the different conditions were not studied, while Heller, and Mauthner (loc. cit.) reported adversely. Thus, ir was evident, that there was room fora thorough and systematic inquiry especially with regard to the temperature, concentration of the catalyst, time, and the nature of the acyl group. Our results, the preliminary note of which was published by us' areas under:-- Hydroquinone.--The diacetate gave 2-acetyl hydroquinone (I) the best yield of which was obtained by using three mols of aluminium chloride for one mol. of the ester, the heating being carried out at ~ for one hour anda hall. If the quantity ofaluminium chloride was reduced, a considerable quantity of 4-acetoxy-2-acetyl-hydroquinone was produced along with (I). The diacetates of 2-methylhydroquinone and 2-chlorohydroquinone gave 2-methyl-5-acetyl-hydroquinone and 2-chloro-5-acetyl hydroquinone together with their mono-acetates. The acetate of quinacetophenone underwent deacetylation. Similarly the dipropionate and the dibenzoate of hydroquinone gave 2-propionylhydroquinone and 2-benzoylhydroquinone together with their monopropionate and monobenzoate. It was not possible to introduce two acyl groups in the molecule of hydroquinone. ResorcinoL--The diacetate gave a mixture of resacetophenone, and 2 ; 4-diacetyl-resorcinol at lower temperatures, while a mixture of these two 269

2 270 R.D. Desai and C. K. Mavani along with 4: 6-diacetyl-resorcinol at higher temperatures. Resoreinol dipropionate and dibutyrate gave respropiophenone and resbutyrophenone together with 2:~4-dipropionyl-and 2: 4-dibutyrylresorcinols, but resorcinol benzoate gave only resbenzophenone. Thus the benzoyl group was quite different in its behaviour from the acetyl, propionyl and butyryl groups. The acetate of resorcinol monomethyl ether gave resacetophenone, as demethylation also took place simultaneously. OrcinoL--The diacetate gave mainly 2:4-diacetylorcinol together with smau quantities of B- and Y-orcacetophenones. When left in contact with" 85 per cent. sulphuric acid, 2: 4-diaeetylorcinol, and B-orcacetophenone gave Y-orcacetophenone and orcinol respectively. Thus this method provides one of the best methods of preparing ~,-orcacetophenone. Orcinol dipropionate and dibutyrate behaved similarly, but the dibenzoate gave only a small quantity of B-orcbenzophenone. EXPERIMENTAL General remarks.--the acetates were prepared by heating the phenols with acetic anhydride in presence of anhydrous sodium acetate, while the propionates and butyrates were prepared by the anhydride method using pyridine asa catalyst. The usual Schotten-Baumann method for benzoylation of phenols was used. General Proeedure of Fries Migration The dry ester (1 mol.) was thoroughly mixed with anhydrous aluminium chloride ( mols.) and heated to the requisite temperature for particular time in ah oil-bath. Ice and dilute hydrochloric acid were added and the resulting solids were examined. The results obtained with the esters of hydroquinone have been shown in Table I. TABLE I F~ter I AICI a in mols. Time in hrs. Temperature Yield and remarks Di~etate.. Dibenzoate " ~ " ~ ~* ~ " 50% of 2-acetylhydroquinone 58~/o of 2-acetylhydroquinone 60% of 2-acet)lhydroquinone 60~/e of 2-acetyl-hydroquinone and its 4-acetoxyderivative 50% os quinbenzophenone 50~ of quinbenzophenone and 4-benzoyloxyquinbenzophenone 60% of quin-propiophenone and 4-propionoxyquinpropiophenone

3 The Frits Rear 271 Hydroquinone dipropionate crystalfised in needles, m.p. 97* (Found: C, 64.6; H, 6.5. Ct2Hx,O4 requires C, 64.9 ; H, 6. per eent.). 2-Propionylhydroquinone crystallised from alcohol in silky needles, m.p. 96", and its alcoholic solution gave green colouration with ferric chloride (Found : C, 64.9 ; H, 6.2. CgH~O~ requires C, 65.1 ; H, 6.0 per cent.). 4-Propionoxy-2-propionyl-hydroquinone obtained by heating the above produet (I gro.) with propionic anhydride (I0 c.c.) crystallised from petroleum r (b.p o) in thick needles, m.p. 5 o. This product was also formed during the Fries Reaction (20~). Its alcoholie solution gave violet colouration with ferric chloride. It undergoes depropionylation giving 2-propionylo hydroquinone when left in contact with 85 per cent. sulphuric acid or subjected to the Fries Reaction (Found: C,64.6; H, 6.4. Ca2Hx404 requires C, 64.9; H, 6. per cent.). 2-Methyl-5.aeetylhydroquinone crystallised from alcohol in colourless needles, m.p. 141 o. Its alcoholic solution gave green colouration with ferric chloride (Found: C, 64.8; H, 6-2. C9H100 requires C, 65.0; H, 6"0 per cent.). 1-Acetoxy-2-methyl-5-acetyl-hydroquinone crystallised from alcohol in stout needles, m.p. 109 o, and its alcoholic solution gave blackish-red colour with ferric chloride (Found: C, 6.2; H, 6-1. ClxH1204 requires C, 6.5; H, 5"8 per cent.). The p-nitrophenylhydrazone of 2-methyl-5-acetyl-hydroquinone crystallised from alcohol in orange plates, m.p. 240 ~ (Found: N, CxsHsO~N requires N, 14.0 per cent.). 2,Chloro.5-acetyl-hydroquinone crystallised from benzene in yellow needles m.p. 145 o. Its alcoholic solution gave green colouration with ferrie ehloride (Found: CI, C,H~O~CI, 19.0 per cent.). 1.Acetoxy.2.chloro.5-acetyl-hydroquinone crystallised from alcohol in straw-yellow needles, m.p. 129 o. Its alcoholic solution gave reddish-orange colouration with ferric chloride (Found: CI, C10H~O,CI requires C per cent.). Quinbenzophenone crystallised from acetie acid in colourless needles, m.p. 125 o, and its alcoholic solution gave green colouration with ferric chloride. 4-Benzoyloxyquinbenzophenone crystallised from petrol in stout needles, m.p. 96, and its alcoholic solution gave red colouration with ferric chloride. On keeping in contact with concentrated sulphuric acid, ir gave quinbenzophenone (Found: C, 75"~ H, 4-6. C20H140~ requires C, 75.5; H, 4.4 per cent.).

4 272 R. D. Desai and C. K. Mavani TABLE II. Fries Migration of the Esters of Resorcinol I AICI s Time in I Temperature Products Ester in mols. hrs. Dlacetate do o. Dibutyrate Dibenzoate R esorcinol-monomethylether mono-acetate 4 Ethylresorcinol diace. tate F~ter TABLE III. AICla i,~ mols. " " " I 0 Resacetophenone (28 per cent.) 2 : 4- diacetyl resorcinol (48.0 per cant) " Resacetophenone (7.0 per cent,) ~ : 4- diacetyl resorcinol 60.0 per cent.) " " Resacetophenone (7.0 per cent.) 2 : 4- diacetyl-resorcinol (48.0 per cent.) 4 : 6-diacetyl resorcinol(14.0 per cent.) " Respropiophenone (25.0 per cent) o :4.dipropionylresorcinol (55.0 per cent.) " Resbutyrophenone (20.0 per cent.) 2 : 4-dlbutyryl-resorcinol (50.0 pro cent.) ~ Resbenzophenone (45.0 per cent. ) Resar (60.0 per cen O 2 : 8-diacetyl-4-ethylresoreinol (65.0 per cent.) Fries Migration of the Esters of Orcinol Time in hrs. i I Temperature Vield and remarks Dtacetate.. do. o do ~176 Dibntyrate.. Dibenzoate.. 1" ~ " ~ ~ l ~ " 2 : 4-Diacetylorcinol (54.0 ~) and mlxture o II- and y-orcaceto phenonc (26"0q~) 2 "4-diacetylorcinol (80.0~) Mixtura of ]8- and Y-orcaceto phenone (12.SqŸ 2 : 4"diacetyl-orcinol (67-0%). Mixtura of 1- and Y-orcaceto pheaone (28.0%) 2 : 4-dipropionylorcinol (60.0~) Mixture of B and Y.orcpropiophenone (20.0~) 9. :4dibutyrylorcinol (.0~) Mixture of B- anal Y-orcbutyrophenone (20.0~,) Mixture of B- and Y- orcbenzophenone (25.0~0) Conversion of 2: 4-diacylorcinols into Y-acylorcinols The mixture of the diacylorcinol (1 gm.) in 85 per cent. sulphuric acid (10 c.c.) was kept for four hours, and the product obtained by pourin8 the

5 The Fries Rear 2~~ solution over ice was crystallised from dilute alcohol. The conversion was almost quantitative. The dibenzoate of 2:4-diacetylorcinol crystallised from acetic acid in long, colourless needles, m.p. 106 ~ (Found: C, 71.8; H, 5.0. CuH:00, requires C, 72.1; H, 4.8 per cent.). Reduction of dipropionylorcinol to 2: 4-dipropylorcinol A mixture of amalgamated zinc (5 g.), the ketone (! g.) and dilute hydrochloride acid (15 c.c.) was heated on sand-bath under reflux for hours. The cooled mixture was extracted with ether, and the solid recovered on the removal of the solvent crystauised from petrol (40-60 b.p.) in needles, m.p. 85 o. (Yield 60.0 per cent.) (Found: C, 74.8; H, 9.7. CxaH~O2 requires C, 75.0; H, 9"6 per cent.). 2: 4-dibutyrylorcinol crystallised from dilute acetic acid in colourless needles, m.p. 67 o. Its alcoholic solution gave blackish-red colouration with ferric chloride, and on treatment with 85 per cent. sulphuric acid, it gave Y-orcbutyrophenone (Found: C, 68.1; H, 7-8. Cx6H2004 requires C, 68.2; H, 7-6 per cent.). Y-orcbenzophenone crystallised from alcohol in pale-yeuow needles, m.p. 127 o. Its alcoholic solution gave greenish black colouration with ferric chloride (Found: C, 7.4; H, 5.5. Cx,Hx~Oa requires C, 7.7; H, 5. per cent.). We express our thanks to Rey. Father A. M. Coyne, s.s., for the provision of facilities. SUMMARY The Fries migration of the esters of hydroquinone, resorcinol and orcinol have been studied under various conditions of temperature. A new and r method of the preparation of Y-acyl-orr has been disr 1. Rosenmund and Lohfert 2. MiUer, Hartung, Rock and Crossley. Rosenmund and Co-workers.. 4. Baker, J,.. 5. Venkataraman and Gulati, J Klarmaun.. 7. Mauthner.. 8. Heller.. 9. Desai and Mavani.. REFERENCES.. Ber., 1928, 61, J. Amer. Chem. Soc., 198, 60, 7. Arch. Pharm., 1927t 265, 08 ; 19, 271, 42. J. Chem. Soc., 194, J., 191, 276. J. Am. Chem. Soc., 1926, 48, 258. J. Pr. Chem. (2), 19, 16, 205. Ber., 1912j 45, 289. Current Science, 1941, 10, 524.