Thallium(III) Perchlorate Hexahydrate

Tl(ClO4)3.6H2O

[15596-83-5]  · Cl3O12Tl  · Thallium(III) Perchlorate  · (MW 610.85)

(oxidizing agent; mild Lewis acid for alkene cyclization)

Physical Data: melts with decomposition.

Solubility: sol water.

Form Supplied in: colorless hygroscopic crystals; widely available. Drying: compound decomposes on heating.

Handling, Storage, and Precautions: all thallium compounds are extremely toxic to inhalation, skin contact, and ingestion. Toxicity is cumulative. Extreme caution should be used when handling these materials. All perchlorates are potentially explosive and appropriate care should be exercised. Use in a fume hood.

Oxidations.

Thallium perchlorate is an efficient oxidizing agent. It converts p-alkylphenols to the corresponding p-quinols in high yields.1 Oxidation of 5-hydroxyindan to 6-hydroxybicyclo[4.3.0]nona-1,4-dien-3-one can be achieved in 80% yield by a biphasic reaction using methylene chloride and aqueous thallium perchlorate solution at low temperatures (eq 1).

Alternatively, oxidation of p-alkylphenols using higher concentrations of perchloric acid at rt provides 2-substituted hydroquinones by a dienone-phenol rearrangement. The hydroquinones are further oxidized to substituted benzoquinones (eq 2).2

A selective and remote oxidation of estrone using thallium perchlorate has been reported (eq 3).3 Oxidation of estrone provides the 11-keto-p-quinol (1) as the major product, along with lesser amounts of (2). This is in contrast to oxidation with Thallium(III) Trifluoroacetate, where (2) is formed as the sole product.4

Enol ethers of alkyl aryl ketones are oxidized very selectively to 2-aryl alkanoates using thallium perchlorate (eq 4).5 Similar oxidations can also be achieved using other thallium(III) salts such as Thallium(III) Nitrate, Thallium(III) Sulfate, and Thallium(III) Acetate.

Reactions with Alkenes.

Thallium perchlorate has been effectively used for ring-expansion of cyclic ketones.6 The sequence involves the formation of exocyclic alkenes from the ketone by a Wittig reaction, followed by oxidation using thallium perchlorate (eq 5). The ring expansion is most effective when the double bond is exocyclic to four- or five-membered rings.

Polyalkenes can cyclize on treatment with thallium perchlorate. For example, geraniol reacts with thallium perchlorate to provide three carbocyclic products (eq 6).7 The reaction is noteworthy since cyclization yields the five-membered carbocycle predominantly.

In contrast to its geometrical isomer geraniol, nerol reacts with thallium perchlorate to furnish two isomeric oxabicyclo[3.2.1]octanes and four diastereomeric dioxabicyclo[3.3.1]nonanes (eq 7).8

Citral also undergoes a similar cyclization on treatment with thallium perchlorate, yielding diastereomeric dioxabicyclo[3.2.1]octanes (eq 8).9


1. Yamada, Y.; Hosaka, K.; Sanjoh, H.; Suzuki, M. CC 1974, 661.
2. Yamada, Y.; Hosaka, K. S 1977, 53.
3. Yamada, Y.; Hosaka, K.; Sawahata, T.; Watanabe, Y.; Iguchi, K. TL 1977, 2675.
4. Coombs, M. M.; Jones, M. B. CI(L) 1972, 169.
5. Walker, J. A.; Pillai, M. D. TL 1977, 3707.
6. Farcasiu, D.; Schleyer, P. v. R.; Ledlie, D. B. JOC 1973, 38, 3455.
7. Yamada, Y.; Sanjoh, H.; Iguchi, K. CC 1976, 997.
8. Yamada, Y.; Sanjoh, H.; Iguchi, K. TL 1979, 1323.
9. Yamada, Y.; Sanjoh, H.; Iguchi, K. TL 1979, 423.

Mukund P. Sibi

North Dakota State University, Fargo, ND, USA



Copyright 1995-2000 by John Wiley & Sons, Ltd. All rights reserved.