Oxidation of benzaldehydes to benzoate esters using household bleach and sodium iodide in alcohol solvents

Article abstract of DOI:10.1080/00397911.2013.833626

Various substituted benzaldehydes were converted into benzoate esters with household bleach and sodium iodide in an alcohol solvent. The reaction works best with methanol. Only 4-chlorobenzaldehyde, 3-nitrobenzaldehyde, and 4-nitrobenzaldehyde reacted completely with 1-propanol under these conditions. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resource(s): Full experimental and spectral details.] Copyright

Full text of DOI:10.1080/00397911.2013.833626

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Oxidation of Benzaldehydes to Benzoate
Esters Using Household Bleach and
Sodium Iodide in Alcohol Solvents
a
a
Bruce A. Hathaway , Christopher A. D. DeKastle & Brianna A.
a
Arnett
a
Department of Chemistry and Physics , LeTourneau University ,
Longview , Texas , USA
Accepted author version posted online: 28 Oct 2013.Published
online: 27 Dec 2013.
To cite this article: Bruce A. Hathaway , Christopher A. D. DeKastle & Brianna A. Arnett (2014)
Oxidation of Benzaldehydes to Benzoate Esters Using Household Bleach and Sodium Iodide in Alcohol
Solvents, Synthetic Communications: An International Journal for Rapid Communication of Synthetic
Organic Chemistry, 44:5, 660-664, DOI: 10.1080/00397911.2013.833626
To link to this article: http://dx.doi.org/10.1080/00397911.2013.833626
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1
Synthetic Communications , 44: 660–664, 2014
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2013.833626
OXIDATION OF BENZALDEHYDES TO BENZOATE
ESTERS USING HOUSEHOLD BLEACH
AND SODIUM IODIDE IN ALCOHOL SOLVENTS
Bruce A. Hathaway, Christopher A. D. DeKastle, and
Brianna A. Arnett
Department of Chemistry and Physics, LeTourneau University,
Longview, Texas, USA
GRAPHICAL ABSTRACT
Abstract Various substituted benzaldehydes were converted into benzoate esters with
household bleach and sodium iodide in an alcohol solvent. The reaction works best with
methanol. Only 4-chlorobenzaldehyde, 3-nitrobenzaldehyde, and 4-nitrobenzaldehyde
reacted completely with 1-propanol under these conditions.
[Supplementary materials are available for this article. Go to the publisher’s online
1
edition of Synthetic Communications for the following free supplemental resource(s):
Full experimental and spectral details.]
Keywords Benzaldehydes; bleach; esters; iodide; oxidation
INTRODUCTION
Previously, we reported on iodination of hydroxy- and methoxy-substituted
[
1,2]
benzaldehydes using iodine and silver nitrate
[3,4]
and using iodine and periodic
have reported that vanillin and similar compounds may
[
acid. Other authors,
2]
be iodinated using sodium hypochlorite and either sodium iodide or potassium iod-
ide in methanol. We reacted 4-methoxybenzaldehyde, 1a, with sodium hypochlorite
and sodium iodide in methanol, 2a, and discovered no ring iodination occurred.
Instead, the methyl ester, methyl 4-methoxybenzoate, 3a, was isolated in 59% yield.
The reaction is shown in Scheme 1.
The conditions of this reaction were modified systematically, to see if the yield
of 3a could be improved. The results are shown in Table I.
Received June 28, 2013.
Address correspondence to Bruce A. Hathaway, Department of Chemistry and Physics, LeTourneau
University, 2100 S. Mobberly Avenue, Longview, TX 75607-7001, USA. E-mail: brucehathaway@
letu.edu
6
60

OXIDATION OF BENZALDEHYDES
661
Scheme 1. Reaction of 4-methoxybenzaldehyde with bleach and sodium iodide in methanol.
As can be seen be seen in entries 1 and 2, both sodium iodide and bleach are
[
5]
required for the esterification to occur. It had been previously reported that esters
could be formed from benzaldehydes using 1–2 equivalents of bleach and acetic acid
in methanol. As shown in entry 3, under these conditions we isolated an approxi-
mately 3:1 mixture (by NMR) of 1a and 3-chloro-4-methoxybenzaldehyde, with
no indication of ester products formed. Modifying our original procedure by doub-
ling the amount of either sodium iodide or bleach (entries 5 and 6) increased the yield
some, but doubling both (entry 7) increased the yield to 79%. Increasing the amount
of sodium iodide further did not increase the yield (entry 8), nor did increasing the
reaction time (entry 9). Entry 10 was tried to see if sodium iodide might have a
catalytic role (oxidized to iodine and subsequently reduced back to iodide), but a
3
:1 mixture of 1a:3a was formed after 17 h of stirring. Using 3 equivalents each of
[
6]
iodine and potassium carbonate in methanol under our reaction conditions yielded
a 5:1 mixture of 1a:3a.
After optimizing the reaction conditions, we submitted various substituted
benzaldehydes to these conditions. Other alcohols were also tried. This is illustrated
in Scheme 2. The successful reactions are shown in Table 2.
Most benzaldehydes reacted with methanol to form methyl esters in yields of
around 80%. The isolated solid products were pure (no evidence of aldehyde or
alcohol starting materials, or byproducts, by proton NMR), and did not require
Table 1. Optimization of reaction conditions with 4-methoxybenzaldehyde (1a) and methanol (2a)
Equiv.
of 1a
Equiv.
of NaI
Equiv. of
NaOCl
Entry
Other
Yield (%) of ester 3a or other result
a
1
2
3
1
1
1
1
0
0
0
1
2
0
NAR
NAR
0
2 acetic acid
Mixture of 1a and
-chloro-4-methoxybenzaldehyde (3:1)
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
2
1
1
2
2
2
2
2
0
0
58%
62%
0
1
0
67%
79%
2
0
5
0
70%
74%
2
Stir 17 h
Stir 17 h
1
0
1
0.2
0
1a and 3a (7:3)
1a and 3a (5:1)
1
2 2 3
3 I and 3 K CO
a
NAR means no apparent reaction.

662
B. A. HATHAWAY, C. A. D. DEKASTLE, AND B. A. ARNETT
Scheme 2. General reaction of benzaldehydes with bleach and sodium iodide in alcohol solvents.
further purification. However, 2-, 3-, and 4-hydroxybenzaldehydes formed mixtures
of mono- and di-iodinated products, even when using 1 equivalent of sodium iodide
and sodium hypochlorite. 3,4-Dimethoxybenzaldehyde cleanly formed the methyl
ester, with no ring iodination. This is in contrast to what we reported using silver
[
2]
nitrate and iodine, where only ring iodination was observed.
Attempts to use other alcohols were not as successful. These results are shown
in Table 3.
The products formed when using ethanol and 1-propanol as solvents with
a were contaminated with starting aldehyde: the reaction apparently did not go
1
to completion in these solvents. No ester was detected in the reaction of 1a with
-propanol. The use of ethanol and 2-propanol also led to formation of some iodo-
2
form, which contaminated the ester products. This is not unexpected, because bleach
readily promotes the iodoform reaction, and basic solutions of iodine can also oxidize
[7]
primary and secondary alcohols to carbonyl compounds. The reaction of benzal-
dehyde with 1-propanol formed mostly ester, but there was still unreacted
benzaldehyde. The only reactions that produced pure ester products were using
4
Other authors
-chlorobenzaldehyde, 3-nitrobenzaldehyde, and 4-nitrobenzaldehyde with 1-propanol.
have proposed that hemiacetals are intermediates in similar
[6,8,9]
oxidations using hypochlorite. Perhaps only the carbonyls of these aldehydes form
significant amounts of the hemiacetals with the larger alcohols, which can then be
oxidized to esters under these conditions.
Table 2. Successful reactions and yields of ester products
Yield (%)
of ester
Aldehyde
G
Alcohol
R
Ester
1
1
1
1
1
1
1
1
1
1
a
b
c
d
e
f
4-CH
3
O
2a
2a
2a
2a
2a
2a
2a
2b
2b
2b
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
3
3
3
3
3
3
3
2
2
2
3a
3b
3c
3d
3e
3f
79
86
85
76
84
73
80
74
81
81
4-CH
4-Cl
3
3-NO
4-NO
3,4-(CH
H
2
2
3 2
O)
g
d
e
c
3g
3h
3i
3-NO
4-NO
4-Cl
2
CH
CH
CH
3
3
3
CH
CH
CH
2
2
2
2
3j

OXIDATION OF BENZALDEHYDES
663
Table 3. Results of reactions of ethanol, 1-propanol, or 2-propanol (30 mL) and various aldehydes
7 mmol), with 2 equivalents each of sodium iodide and sodium hypochlorite
(
Aldehyde
G
Alcohol
Ethanol
Results
1a
4-CH
3
O
Iodoform (0.58 g) and an oil (0.82 g, which was
a 7:1 mixture of 1a and ester)
1
a
a
4-CH
4-CH
3
O
O
1-Propanol
2-Propanol
0.91 g of an oil, which was a 6:1 mixture 1a and ester
Iodoform (1.004 g) and an oil, which was 1a
1
3
(
0.86 g, 91% recovery)
1g
1e
1e
4-H
1-Propanol
Ethanol
2-Propanol
0.82 g of an oil, which was a 1:10 mixture of 1g and ester
1.33 g of solid, which was a 10:1 mixture of ester and iodoform
1.13 g of solid, which was a 3:5:1 mixture of 1e,
ester, and iodoform
4-NO
4-NO
2
2
In conclusion, a number of simple benzaldehydes can be oxidized to methyl
esters using sodium iodide and household bleach in methanol in good yields. The
procedure and product isolation are simple for solid esters, and the esters are pure,
with no unreacted benzaldehyde, as determined by proton NMR spectroscopy. In
addition, 4-chlorobenzaldehyde, 3-nitrobenzaldehyde, and 4-nitrobenzaldehyde also
form pure ester products with 1-propanol.
EXPERIMENTAL
Melting ranges were recorded using a MelTemp apparatus and are reported
in C. NMR spectra were recorded on a Bruker DPX-300 or on an Anasazi
ꢀ
EFT-upgraded Varian EM-360, using CDC1 or dimethylsulfoxide (DMSO-d ) as
3
6
a solvent.
-Methoxybenzaldehyde, 1a (0.95 g, 7.0 mmol), sodium iodide (2.10 g,
4.0 mmol), and methanol, 2a (30 mL) were added to a 250-mL Erlenmeyer flask.
4
1
The mixture was stirred until the solids dissolved and then stirred in an ice-water bath
for 10 min. Commercial household bleach (either 22 mL of a 5.25% solution or 15 mL
of an 8% solution, which was titrated with standard sodium thiosulfate solution to
determine the actual concentration of sodium hypochlorite) (14 mmol) was added
dropwise over 20 min to the cooled reaction mixture: The solution turned brown with
the addition of bleach. The ice bath was removed, and the reaction mixture was
stirred for 1 h. Enough sodium thiosulfate solution (either 5% or 10%) was added
to discharge the iodine color. The solution was diluted with 100 ml of water and
allowed to stand in an ice bath until precipitation of the solid product was
complete. The solid was filtered by suction, washed with water, and allowed to
ꢀ
ꢀ
[10]
dry. Compound 3a was a white solid, melting range: 46–47 C (literature 49 C ).
1
H NMR (300 MHz, CDCl ), d (ppm): 8.00 (d, J ¼ 9.0 Hz, 2H), 6.92 (d, J ¼ 9.0 Hz,
3
1
3
Hz, 2H), 3.89 (s, 3H), 3.85 (s, 3H). C NMR (75.5 MHz, CDCl ), d (ppm): 166.9,
3
1
literature.
63.3, 131.6, 122.6, 113.6, 55.4, 51.9. The spectral data agreed with that in the
[
11]
In those cases where the product did not solidify upon cooling, the reaction
mixture was extracted with dichloromethane (2 ꢁ 25 mL). The combined dichloro-
methane extracts were washed with water and saturated sodium chloride solution,

664
B. A. HATHAWAY, C. A. D. DEKASTLE, AND B. A. ARNETT
and dried over sodium sulfate. The solvent was removed under reduced pressure. For
product mixtures, the integrations of the aldehyde protons and the ester O-CH or
2
O-CH protons were used to obtain the product ratios. If iodoform was present in
a mixture, it was quantitated by its distinctive NMR signal at 4.90 ppm in CDCl3.
SUPPORTING INFORMATION
1
13
Full experimental details, melting ranges, and H and C NMR spectral data
for compounds 3b–j can be found via the Supplementary Content section of this
article’s Web page.
ACKNOWLEDGMENTS
The authors gratefully acknowledge the Welch Foundation for Departmental
Research Grant BL-0028, for partial support of this work, and the Chemistry
Department of Southeast Missouri State University, for use of their facilities and
their Bruker DPX-300 NMR spectrometer.
REFERENCES
1. Hathaway, B. A.; Taylor, B. E.; Wittenborn, J. S. Synth. Commun. 1998, 28, 4629–4637.
2. Hathaway, B. A.; White, K. L.; McGill, M. E. Synth. Commun. 2007, 37, 3855–3860.
3. Doxsee, K.; Hutchison, J. Green Organic Chemistry: Strategies, Tools, and Laboratory
Experiments, 1st ed.; Brooks=Cole: Belmont, CA, 2004.
4
5
. Edgar, K. J.; Falling, S. N. J. Org. Chem. 1990, 55, 5287–5291.
. Stevens, R. V.; Chapman, K. T.; Stubbs, C. A.; Tam, W. W.; Albizati, K. F. Tetrahedron
Lett. 1982, 23, 4647–4650.
6. Mori, N.; Togo, H. Tetrahedron 2005, 61, 5915–5925.
7. Pasto, D.; Johnson, C.; Miller, M. Experiments and Techniques in Organic Chemistry;
Prentice Hall: Englewood Cliffs, NJ, 1992; pp. 326–328.
8
9
. Yamada, S.; Morizono, D.; Yamamoto, K. Tetrahedron Lett. 1992, 33, 4329–4332.
. McDonald, C.; Holcomb, H.; Kennedy, K.; Kirkpatrick, E.; Leathers, T.; Vanemon, P.
J. Org. Chem. 1989, 54, 1213–1215.
10. Weast, R. C. (Ed.). CRC Handbook of Chemistry and Physics, 51st ed.; Chemical Rubber
Company: Cleveland, OH, 1970.
11. Spectral Database for Organic Compounds SDBS, SDBS #2319. Available at http://
sdbs.riodb.aist.go.jp/sdbs/cgi-bin/direct_frame_top.cgi