Solid phase oxidation of alcohols and benzyl halides to carbonyls using bromate exchange resin

Article abstract of DOI:10.1081/SCC-120023429

Aromate exchange resin prepared by a simple elution technique and used for the biphasic oxidation of alcohols and benzyi halides to corresponding carbonyl compounds.

Full text of DOI:10.1081/SCC-120023429

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SYNTHETIC COMMUNICATIONSÕ
Vol. 33, No. 18, pp. 3147–3151, 2003
Solid Phase Oxidation of Alcohols and
Benzyl Halides to Carbonyls Using Bromate
Exchange Resin
Atul Pd. Sikdar, Ajoy B. Chetri, Gakul Baishya,
*
and Pranab J. Das
Department of Chemistry, Gauhati
University, Guwahati, India
ABSTRACT
Aromate exchange resin prepared by a simple elution technique and
used forthe biphasic oxidation of alcohols and benzyi halides to
corresponding carbonyl compounds.
Key Words: Bromate exchange resin; Solid phase; Oxidation;
Alcohols.
*Correspondence: Pranab J. Das, Department of Chemistry, Gauhati
University, Guwahati 781 014, India; E-mail: pjd123@sify.com.
3147
DOI: 10.1081/SCC-120023429
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3148
Sikdar et al.
Ion exchange resin are the earliest known support for reagents and
catalysts in organic synthesis.[1] Among the advantages of supported
reagents in organic synthesis are easy work-up procedure, mild reaction
condition, site specific reactions, and high turn over. Supported reagents
are also environment friendly.[2–6]
In continuation of our work in the field of ion exchange resin
supported reagents in organic synthesis, we had earlier reported the use
of bromate exchange resin as an oxidizing agent for the oxidation of
aldehyde to the carboxylic acids.[7] We now report the use of bromate
exchange resins for the oxidation of alcohols and benzylhalides to the
corresponding carbonyl compounds in biphasic condition. An important
observation is that primary alcohols were oxidized only to the aldehydes
and overoxidation to the carboxylic acid was not observed.
In our earlier communication, we had reported a method of
immobilizing Bromate ion onto ion exchange resin namely Amberlite
IRA-400(Clꢀ). The extent of loading of bromate ions was likewise
reported to be 0.9 mequivalent per gram of resin.
The bromate exchange resin so obtained was used for the oxidation
alcohols and benzyl halides to the corresponding carbonyl compounds.
Primary alcohols and halides were oxidized to aldehydes, a transformation
which is synthetically useful. The reaction were carried out under biphasic
condition in organic solvents. Work-up procedure is simple and involves
filtration and removal of solvent. Conversion was found to be as high as
90% in some cases. The products were identified by comparing their m.p.,
1
IR, UV, and H NMR spectra with authentic samples. Identification of
products were also done by conversion to their 2,4-DNP derivatives and
the percentage yield ascertained by this procedure.
EXPERIMENTAL
The anion exchange resin used was AmberliteIRA-400(Clꢀ), 20–50
mesh, according to Rohm and Hass specification obtained from Loba
Cheme (India). The resin was washed several times with deionized water
and dried. All starting materials were purified before use and sodium
bromate was used as a source of bromate ions.
Five grams dry bromate exchange resin was eluted several times with
the same volume (100 ml) of 1 M aqueous KCl to ensure complete
exchange of BrOꢀ3 with Cl. The resin was further washed with distilled
water. The combined volume of the elutent and washing collected and
made up to 250 ml. The bromate present in this solution was estimated by

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Bromate Exchange Resin
3149
Scheme 1.
Table 1. Oxidation of alcohols to carbonyl compounds.
M.p of
Reflux Yieldb product (ꢁC)
M.p. of 2,4-DNP
deriv. (ꢁC)
obs. (lit.)
Sl.
no.
Substrate
Product
time (h) (%)
obs. (lit.)
1.
2.
8
8
95
95
93 (95)
191 (189)
238 (238)
50 (48)
3.
4.
10
10
88
81
Liquida
Liquida
248 (255)
160 (160)
5.
6.
7
72
74
Liquida
Liquida
213 (218)
236 (240)
12
7.
12
77, 84
Liquida
236 (240)
8.
9.
8
75
80
54 (56)
72 (74)
240 (244)
10
Above 270 (320)
(continued )

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3150
Sikdar et al.
Table 1. Continued.
M.p of
Reflux Yieldb product (ꢁC)
M.p. of 2,4-DNP
deriv. (ꢁC)
obs. (lit.)
Sl.
no.
Substrate
Product
time (h) (%)
obs. (lit.)
10.
11.
7
8
80
78
46 (47)
260 (265)
250 (253)
Liquida
12.
13.
8
88
88
Liquida
41 (42)
246 (240)
227 (227)
10
aLiquid products directly converted to the hydrazone.
bYield calculated on the basis of hydrazone obtained. M.p. determined in open
capillaries.
a standard procedure according to the reaction
BrOꢀ3 þ 6lꢀ þ 6Hþ ¼ Br þ 3l2 þ 3H2O
The amount of loading was found to be 0.9 mequivalent pergram of
resin.[8]
OXIDATION WITH RESIN IMMOBILIZED BROMATE
(GENERAL PROCEDURE)
To 0.01 mole of the substrate dissolved in 100 ml of dioxane was
added 15 g of the bromate exchange resin and the solution stirred at
reflux temperature. The progress of the reaction was monitored by
TLC on silica gel-G plate till complete conversion was observed. The
solution was filtered and the product was obtained by removal of solvent
by distillation under reduced pressure. The products obtained were
converted to their 2,4-DNP derivatives by standard procedures. The
results are summarized in Sch. 1 and Table 1. It may also be mentioned
that the reaction time can be reduced if 2–3 drops of conc. H2SO4 are
added to the reaction mixture. This is due to the rapid decomposition of

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Bromate Exchange Resin
3151
bromate ions by the action of mineral acid to give oxygen which now acts
as the primary oxidant.
The study revealed the versatility of bromate ions for the oxidation
of organic substrates provided they were immobilized onto an ion
exchange resin. Simplicity of workup procedure is an added advantage.
The oxidation of halides and alcohols to aldehydes by this procedure is
noteworthy.
REFERENCES
1. Leznoff, C.C. Quart. Rev. Chem. Soc. 1974, 3, 65.
2. Shimo, K.; Wakamatsu, S. J. Org. Chem. 1963, 28, 504.
3. Collins, M.; Laws, D.S.J. J. Chem. Soc. Perkin Trans. 1 1973, 2013.
4. Cainelle, G.; Manescalchi, F. Synthesis 1979, 141.
5. Bongini, A.; Cainelli, G.; Contento, M.; Manescalchi, F. Synthesis
1980, 143.
6. Thomas, J.M. Sci. Amer. 1992, 82.
7. Chetri, A.B.; Kalita, B.; Das, P. J. Synth. Commun. 2000, 30, 3317.
8. Field, R.J.; Endre, K.; Noyes, R.M. J. Am. Chem. Soc. 1972,
94, 8649.
Received in the Netherlands September 19, 2001

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