The Journal of Organic Chemistry
Article
introduced into the reaction vessel, and the contents were purged with
a stream of argon. The capped vessel was immersed in an oil bath at
150 °C. After 30 min, heating was discontinued by removing the
reactor from the heat bath and immersing it promptly in cold water.
The reactor heat-up time was on the order of 30 s, which was generally
short compared with the reaction times employed. After cooling, the
crystalline solid product was flushed out of the reaction vessel with
water and collected on a membrane filter as pale yellow needles
(0.0567 g, mp 164−165 °C).35 The reactions at elevated temperature
in water followed by crystallization during the cooling process may
have had an effect similar to recrystallization from hot water.
Additionally, the effects of reaction temperatures and duration of
the reactions were studied in the ranges 100−400 °C and 10−120 min.
A metal salt bath preheated at 200−400 °C was used when needed. In
these studies, the reaction products were extracted with dichloro-
methane, and an aliquot (1 μL) was injected into a column of a gas
chromatograph−mass spectrometer and developed with He gas with a
flow rate of 0.55 mL/min. The amounts of 5 produced were
determined accurately by reference to added 1-pentanol as an internal
standard and on the basis of calibration curves obtained independently
for the pure samples.
product of water and conform to the 12 criteria of green
chemistry in a number of points.29
EXPERIMENTAL SECTION
■
Starting Materials. Preparation of 1-aryl-2-propyn-1-ones is
described in the previous paper.23 Sodium enolate of benzoylacetalde-
hyde (3) was prepared by the condensation of acetophenone and ethyl
formate by the action of sodium methoxide in dry diethyl ether
according to the literature.44,45 The sodium enolate of p-
toluoylacetaldehyde (3′) was prepared similarly.
Commercially available 4-methoxy-3-buten-2-one (4) of chemical
purity greater than 90% was used without further purification.
Ultrapure water with a specific resistivity greater than 18.2 MΩ and
TOC less than 20 ppb was obtained by passing tap water through an
ultrapure water purification system. Other chemicals and solvents
when necessary were commercially available and used as received.
General Experimental Methods. The reactions were performed
in batch reactors (Figure S1, Supporting Information) fabricated out of
a 1/2-in. tube (diameter of 12.7 mm, wall thickness of 2.1 mm) fitted
with two 1/2-in. caps both of grade 316 stainless steel. The effective
inner volumes of ca. 2.1 and 10 cm3 were used for the preparation of
triaroylbenzenes and 1,3,5-triacetylbenzene, respectively. Prior to its
use in experiments, the reactor was loaded with 2% aqueous hydrogen
peroxide and conditioned for 1 h at 370 °C to remove any lubricants/
oils that might remain from the manufacture of the Swagelok parts and
possible catalytic metal sites on the inner-wall, unless otherwise stated.
The reactor was cleaned with acetone and dried prior to repeated safe
use of ca. 5 times. The internal pressure was subjected to the gas−
liquid equilibrium of water and estimated to be 0.48 MPa at 150 °C.
Preparation of 1,3,5-Triaroylbenzene. The crossed reactions: 1-
phenyl-2-propyn-1-one (1) with sodium enolate of p-toluoylacetalde-
hyde (3′) and 1-(p-tolyl)-2-propyn-1-one (1′) with sodium enolate of
benzoylacetaldehyde (3) were mixed in pure water in molar ratios of
0:1:400−4:1:400. After the mixture was purged with a stream of argon,
the sealed reactor was immersed in an oil bath preheated at 150 °C for
120 min. The reactor was cooled by immersing it in cold water to stop
the reaction. The cap was carefully opened, and the contents of the
reactor were washed with dichloromethane. The organic layer was
ASSOCIATED CONTENT
* Supporting Information
■
S
Experimental details concerning raw yield data; NMR and MS
spectra of new compounds Ph2Tol and PhTol2. This material is
AUTHOR INFORMATION
Corresponding Author
■
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
1
analyzed by means of GC/MS and H NMR. Quantitative analyses
We thank Prof. Soichiro Watanabe of Toho University for his
permission and advice on the use and separation of the reaction
mixture using preparative gel permeation chromatography. This
research was supported in part by a Grant from the Ministry of
Education, Culture, Sports, Science and Technology to
promote multidisciplinary research projects.
were performed by 1H NMR with 1,3,5-triacetylbenzene as an internal
standard. Separation of the reaction mixtures was performed by
preparative gel permeation chromatography on a couple of columns of
exclusion size limits of MW 1000 and 5000 (in reference to the
molecular weight of the standard polystyrenes), in series using CHCl3
as an elution solvent. Both had a column volume of i.d. 20 mm × 600
mm. After removal of the acetophenone fractions, the triaroylbenzene
fractions were subjected to repeated recycling of ca. 35 times until
effective separation was obtained.
DEDICATION
■
Dedicated to the memory of Professor Howard E. Zimmerman.
1,3-Dibenzoyl-5-(p-toluoyl)benzene (Ph2Tol). NMR (400
MHz, CDCl3): δ 8.38 (t, J = 1.2 Hz, 1H), 8.37 (d, J = 1.2 Hz, 2H),
7.84(d, J = 7.7 Hz, 4H), 7.76 (d, J = 8.0 Hz, 2H), 7.64 (t, J = 7.6 Hz,
2H), 7.52 (t, J = 7.7 Hz, 4H), 7.31 (d, J = 8.0 Hz, 2H), 2.45 (s, 3H)
(see Figure S3a, Supporting Information, for a chart). MS: 404 (parent
peak), 119 (base peak), 105, 91, 77 (see Figure S2, Supporting
Information).
REFERENCES
■
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MHz, CDCl3): δ 8.38 (d, J = 1.2 Hz, 2H), 8.37 (t, J = 1.2 Hz, 1H),
7.84(d, J = 7.7 Hz, 2H), 7.75 (d, J = 8.0 Hz, 4H), 7.64 (t, J = 7.6 Hz,
2H), 7.61 (t, J = 7.7 Hz, 1H), 7.30 (d, J = 8.0 Hz, 4H), 2.45 (s, 6H)
(see Figure S3b, Supporting Information, for a chart). MS: 418 (parent
peak), 119 (base peak), 105, 91, 77 (see Figure S2, Supporting
Information).
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tribenzoylbenzene (Ph3) and 1,3,5-tri(p-toluoyl)benzene (Tol3)
corresponding to the ions PhCO and CH3C6H4CO, respectively. In
Ph2Tol and PhTol2, both the 105 and 119 peaks were observed in
appropriate relative strength.
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Preparation of 1,3,5-Triacetylbenzene. 4-Methoxy-3-buten-2-
one (4) (0.1033 g) and water (1.8036 g) in a molar ratio of 1:200 were
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dx.doi.org/10.1021/jo301979p | J. Org. Chem. XXXX, XXX, XXX−XXX