a new synthesis of substituted diphenyl ethers

1
111 F. Bentz and G.-E. Nischk, DAS 1235300 (1967), Farben- fabriken Bayer AG. 121 F. Bentz and G.-E. Nischk, DAS 1235302 (1967), Farben- fabriken Bayer AG. 131 Cf. P. A. Petjunin and V. P. Cernyek, 2. org. Chim. 1966,285. [4] F. Bentz, R. Braden, and G.-E. Nischk, DAS 1293741 (1969), Farbenfabriken Bayer AG. H H H H NO2 NO2 CI H H H H H H m.p. 144 "C). A further 28 g can be recovered by concentra- tion of the mother liquor, m.p. 142"C, total yield 91 %. If recrystallized starting material is used, yields of more than 93 of the ether can be obtained. Received: September 5, 1969 [Z 86 1El German version: Angew. Chem. 82, 19 (1970) Publication delayed at authors' request NO2 NO2 c1 A New Synthesis of Substituted Diphenyl Ethers By H. Witt, H. Holtschmidt, and E. Miiller[*] Dedicaied to Professor K. Hansen on the occasion of his 60 th birthday It has already been reported 111 that phenyl o-phenoxy- benzoate can be prepared in high yields by heating a melt of diphenyl carbonate in the presence of small amounts of KzC03 at 23&270 "C. We have now found that the diphenyl ethers (2) can be prepared from 0- and/or p-substituted di- phenyl carbonates (I) when subjected to similar reaction conditions. 'R3 (1) [*I Dr. H. Witt, Prof. Dr. H. Holtschmidt, and Dr. E. Miiller Wissenschaftliches Hauptlaboratorium der Farbenfabriken Bayer AG 509 Leverkusen-Bayerwerk (Germany) [l] P. W. Bachmann and B. W. Hammarin, US-Pat. 2319197 (May 18, 1943) General Chemical Co.; Chem. Abstr. 37, 62807 (1943); A. Davis and 1. H. Golden, J. chem. Soc. (London) B 1968, 40. 121 H. Witt, H. Holtschmidt, and E. Miiller, DAS 1290148 (May 13, 1967), Farbenfabriken Bayer AG. 13) Cf. Th. K. Brotherton and J. W. Lynn, US-Pat. 3256220 (June 14,1966) Union Carbide Corp.; Chem. Abstr. 65,18498 G (1966); J. M. A. Hoeflake, Recueil Trav. chim. Pays-Bas 36, 62 (1916); 40, 510, 513 (1921). Mesoionic 2-Benzoyl-1-benzoylimino- 4,5-dimethyl-l,2,3-triazole By S. Petersen and H. Heitzer [*I Dedicated to Professor K, Hunsen on the occasion of his 60th birthday The oxidation product first prepared by H. v. Pechmann and W. Bauer by reaction of 2,3-butanedione bis(benzoy1hydra- zone) (I) [11 with potassium hexacyanoferratefrrr) wasformulat- ed [21 as 2,3-dibenzoyl-5,6-dimethyl-2,3-diliydrotetraazine (2). Catalyst wt.- % calc. w. r. t. (I) 1 K2CO3 0.5 KOCOCH, 1 KOCOCH, 1 KOCOCHi 1 K2C03 1 KzCO, 1 K2CO3 1 K2C03 Temp. f "C) 210-250 180-205 190-220 156-1 86 186-226 200-242 240-260 200-2 14 17 > 90 41 89 31 65 66 22 [a] Not optimized. A prerequisite for this reaction is that at least one of the groups R1-R" is a second order substituent; preparatively useful yields, however, are obtainable only from symmetri- cally substituted, particularly p,p'-disubstituted, diphenyl carbonates. Numerous other alkali metal compounds may be used as catalysts (in amounts of 0.5-2 wt.-%) instead of potassium carbonate. 4,4'-Dinitrodiphenyl ether (2), Rl=R2=N02, R3=R4=H [21 4,4'-Dinitrodiphenyl carbonate (1 000 g) (crude phosgenation product, m.p. 140 "C) [3J is melted (silicone oil bath) in a 2 1 three-necked flask fitted with stirrer, internal thermometer, and a delivery tube connected via a bubble counter. Potas- sium acetate (5 g) is added slowly, with stirring, to the melt at a temperature of 150 'C. Decarboxylation (18@-205 'C, bath temperature 190-215 "C) is complete after 4-5 hours. The temperature of the mixture is then allowed to drop to 150 'C, and, after the apparatus has been fitted with a reflux condenser, toluene (580 g) is added slowly. The solution is filtered hot from insoluble residue (ca. 8 g). The filtrate is then cooled and the 4,4'-dinitrodiphenyl ether which crys- tallizes out is recovered by filtration, washed with a little methanol, and finally dried in a vacuum (yield 749 g (88 %), H3C ,N-NH-CO-C,H, H3C x N-NH-CO-CBH, H3C The 1H-NMR spectra (in CDC13) of the oxidation product at 60 and 220 MHz 131 show that the compound does not have a symmetrical structure. Two methyl-group signals appear in the 60 MHz spectrum at 2.23 ppm and 2.36 ppm in addition to a multiplet (signal width ca. 20 Hz) centered at 8.1 ppm which is due to the protons of both aromatic rings that are ortho to the carbonyl groups. in the 220 MHz spectrum the multiplet is resolved into two pseudo doublets at 8.116 ppm and 8.236 ppm (J = 7.8 to 8.0 Hz). The remaining six aro- matic protons absorb between 7.4 and 7.8 ppm. On the basis of these findings, therefore, we suggest that the oxidation product has the structure of a mesoionic triazole (3), (3), R = CO-C6H5 which is in agreement with the chemical properties of this compound. The ready hydrolytic and thermal loss of a benzoyl group is now understandable since the compound is being considered as an azolider41. As is already known, com- pound (3) affords l-(dibenzoylamin0)-4,5-dimethyl-1,2,3- triazole (4) 151 when heated and l-benzoylamino-1,2,3-tri- azole (5) when treated with hydrochloric acid. Hydrolysis of (3) with concentrated hydrochloric acid at higher tempera- tures leads to formation of the free 1-amino-4,s-dimethyl- 1,2,3-triazole (6) [21. We have obtained 4-chlorobenzoic an- hydride as reaction product by recrystallizing compound (7) Angew. Chem. internat. Edit. 1 Vol. 9 (1970) 1 No. I 67

Upload: dr-h-witt

Post on 06-Jun-2016

212 views

Category:

Documents


0 download

TRANSCRIPT

111 F. Bentz and G.-E. Nischk, DAS 1235300 (1967), Farben- fabriken Bayer AG. 121 F. Bentz and G.-E. Nischk, DAS 1235302 (1967), Farben- fabriken Bayer AG. 131 Cf. P. A . Petjunin and V. P. Cernyek, 2. org. Chim. 1966,285. [4] F. Bentz, R . Braden, and G.-E. Nischk, DAS 1293741 (1969), Farbenfabriken Bayer AG.

H H H H NO2 NO2 CI H H H H H H

m.p. 144 "C). A further 28 g can be recovered by concentra- tion of the mother liquor, m.p. 142"C, total yield 91 %. If recrystallized starting material is used, yields of more than 93 of the ether can be obtained.

Received: September 5, 1969 [Z 86 1El German version: Angew. Chem. 82, 19 (1970)

Publication delayed at authors' request

NO2 NO2 c1

A New Synthesis of Substituted Diphenyl Ethers

By H . Wit t , H. Holtschmidt, and E. Miiller[*]

Dedicaied to Professor K . Hansen on the occasion of his 60 th birthday

It has already been reported 111 that phenyl o-phenoxy- benzoate can be prepared in high yields by heating a melt of diphenyl carbonate in the presence of small amounts of KzC03 a t 23&270 "C. We have now found that the diphenyl ethers (2) can be prepared from 0- and/or p-substituted di- phenyl carbonates ( I ) when subjected to similar reaction conditions.

'R3 (1)

[*I Dr. H. Witt, Prof. Dr. H. Holtschmidt, and Dr. E. Miiller Wissenschaftliches Hauptlaboratorium der Farbenfabriken Bayer AG 509 Leverkusen-Bayerwerk (Germany)

[l] P . W. Bachmann and B. W. Hammarin, US-Pat. 2319197 (May 18, 1943) General Chemical Co.; Chem. Abstr. 37, 62807 (1943); A . Davis and 1. H . Golden, J. chem. Soc. (London) B 1968, 40. 121 H. Witt, H . Holtschmidt, and E. Miiller, DAS 1290148 (May 13, 1967), Farbenfabriken Bayer AG. 13) Cf. Th. K. Brotherton and J. W. Lynn, US-Pat. 3256220 (June 14,1966) Union Carbide Corp.; Chem. Abstr. 65,18498 G (1966); J . M . A. Hoeflake, Recueil Trav. chim. Pays-Bas 36, 62 (1916); 40, 510, 513 (1921).

Mesoionic 2-Benzoyl-1-benzoylimino- 4,5-dime thyl-l,2,3-triazole

By S. Petersen and H . Heitzer [*I

Dedicated to Professor K, Hunsen on the occasion of his 60th birthday

The oxidation product first prepared by H . v. Pechmann and W. Bauer by reaction of 2,3-butanedione bis(benzoy1hydra- zone) ( I ) [11 with potassium hexacyanoferratefrrr) wasformulat- ed [21 as 2,3-dibenzoyl-5,6-dimethyl-2,3-diliydrotetraazine (2).

Catalyst wt.- % calc. w. r. t. ( I )

1 K2CO3 0.5 KOCOCH, 1 KOCOCH, 1 KOCOCHi 1 K2C03 1 KzCO, 1 K2CO3 1 K2C03

Temp. f "C)

210-250 180-205 190-220 156-1 86 186-226 200-242 240-260 200-2 14

17 > 90 41 89 31 65 66 22

[a ] Not optimized.

A prerequisite for this reaction is that a t least one of the groups R1-R" is a second order substituent; preparatively useful yields, however, are obtainable only from symmetri- cally substituted, particularly p,p'-disubstituted, diphenyl carbonates. Numerous other alkali metal compounds may be used as catalysts (in amounts of 0.5-2 wt.-%) instead of potassium carbonate.

4,4'-Dinitrodiphenyl ether (2), Rl=R2=N02, R3=R4=H [21

4,4'-Dinitrodiphenyl carbonate (1 000 g) (crude phosgenation product, m.p. 140 "C) [3J is melted (silicone oil bath) in a 2 1 three-necked flask fitted with stirrer, internal thermometer, and a delivery tube connected via a bubble counter. Potas- sium acetate (5 g) is added slowly, with stirring, to the melt a t a temperature of 150 'C. Decarboxylation (18@-205 'C, bath temperature 190-215 "C) is complete after 4-5 hours. The temperature of the mixture is then allowed to drop to 150 'C, and, after the apparatus has been fitted with a reflux condenser, toluene (580 g) is added slowly. The solution is filtered hot from insoluble residue (ca. 8 g). The filtrate is then cooled and the 4,4'-dinitrodiphenyl ether which crys- tallizes out is recovered by filtration, washed with a little methanol, and finally dried in a vacuum (yield 749 g (88 %),

H3C ,N-NH-CO-C,H,

H3C x N-NH-CO-CBH, H3C

The 1H-NMR spectra (in CDC13) of the oxidation product at 60 and 220 MHz 131 show that the compound does not have a symmetrical structure. Two methyl-group signals appear in the 60 MHz spectrum at 2.23 ppm and 2.36 ppm in addition to a multiplet (signal width ca. 20 Hz) centered at 8.1 ppm which is due to the protons of both aromatic rings that are ortho to the carbonyl groups. i n the 220 MHz spectrum the multiplet is resolved into two pseudo doublets at 8.116 ppm and 8.236 ppm ( J = 7.8 to 8.0 Hz). The remaining six aro- matic protons absorb between 7.4 and 7.8 ppm. On the basis of these findings, therefore, we suggest that the oxidation product has the structure of a mesoionic triazole (3),

(3), R = CO-C6H5

which is in agreement with the chemical properties of this compound. The ready hydrolytic and thermal loss of a benzoyl group is now understandable since the compound is being considered as an azolider41. As is already known, com- pound (3) affords l-(dibenzoylamin0)-4,5-dimethyl-1,2,3- triazole (4 ) 151 when heated and l-benzoylamino-1,2,3-tri- azole ( 5 ) when treated with hydrochloric acid. Hydrolysis of (3) with concentrated hydrochloric acid at higher tempera- tures leads to formation of the free 1-amino-4,s-dimethyl- 1,2,3-triazole ( 6 ) [21. We have obtained 4-chlorobenzoic an- hydride as reaction product by recrystallizing compound (7)

Angew. Chem. internat. Edit. 1 Vol. 9 (1970) 1 No. I 67