ortho Diquaternary Aromatic Compounds. IV. Acid-catalyzed Rearrangements of Polyalkyltetralones and Related Ketones
The ketones 1,1,4,4-tetramethyl-2-tetralone ( 1 a), 1,1,4,4,7-pentamethyl-2-tetralone ( 1 b), and 1,1,4,4,6-pentamethyl-2-tetralone ( 1 c) undergo rearrangement on heating with aluminum chloride or ferric chloride in tetrachloroethane or nitromethane into mixtures of their respective isomeric ketone...
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Veröffentlicht in: | Canadian journal of chemistry 1973-05, Vol.51 (10), p.1598-1609 |
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Hauptverfasser: | , , , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | The ketones 1,1,4,4-tetramethyl-2-tetralone (
1
a), 1,1,4,4,7-pentamethyl-2-tetralone (
1
b), and 1,1,4,4,6-pentamethyl-2-tetralone (
1
c) undergo rearrangement on heating with aluminum chloride or ferric chloride in tetrachloroethane or nitromethane into mixtures of their respective isomeric ketones, 1-acetyl-1,3,3-trimethylindane (
2
a) and 2,2,4,4-tetramethyl-1-tetralone (
3
a) from
1
a, 1-acetyl-1,3,3,6-tetramethylindane (
2
b) and 2,2,4,4,7-pentamethyl-1-tetralone (
3
b) from
1
b, and 1-acetyl-1,3,3,5-tetramethylindane (
2
c) and 2,2,4,4,6-pentamethyl-1-tetralone (
3
c) from
1
c. A quantitative study using g.l.c. of the distribution of the ketones with time shows that the sequence of the rearrangement is:
. A methyl group homologously para to the carbonyl (
1
c) accelerates the rearrangement. The same kind of rearrangement takes place during Friedel-Crafts cyclialkylation with 2,2,5,5-tetramethyltetrahydrofuranone. A unifying reaction mechanism is postulated to account for the rearrangements. This mechanism also accounts for the rearrangement and fragmentation products from treatment of 1,1,4,4-tetramethyl-2,3-dioxotetralin (
9
) with aluminum chloride or sulphuric-acetic acids. The products from
9
include 1-acetyl-1,3,3-trimethyl-2-indanone, 1,1,3-trimethyl-2-indanone, and, from the aluminum chloride - catalyzed rearrangement, 5(or 6)-acetyl-1,1,3-trimethyl-2-indanone. |
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ISSN: | 0008-4042 1480-3291 |
DOI: | 10.1139/v73-240 |