Non-catalytic condensation of aromatic aldehydes with aniline in high temperature water

Figures & data

short-legendScheme 1. Condensation of aromatic aldehydes with aniline in near critical water.

Table 1. Yield of 3a at different temperatures after 3 min.

Entry	Temperature (°C)	Yield (%)
1	100	53
2	200	75
3	350	98
4	400	87
5	350	98
6	350	93

short-legendScheme 2. Mechanism for the formation of diamino triphenyl methane.

Table 2. Yield of 3a at different water densities.

Entry	Water density^a (±0.01 g cm^−3)	Pressure (MPa)	Yield (%)^b
1	0.06	13.3	83
2	0.16	20.6	89
3	0.20	21.9	91
4	0.30	23.7	94
5	0.40	24.1	98
^aThe water density was defined as the mass of water (g) in the vessel (cm^3) to±0.01 g cm^−3.
^bReaction conditions: temperature = 350 °C; reaction time = 3 min.

Table 3. Condensation of aromatic aldehydes with aniline in near critical water.

Entry	X	Yield (%)^a
A	Cl	98
B	H	93
C	Br	96
D	NO2	94
E	OMe	89
^aReaction conditions: temperature = 350 °C; reaction time = 3 min.

Table 4. Comparison of our results with results obtained by other groups with some heterogeneous acid catalyst for the synthesis of 3b.

Catalyst (0.5 g)	Condition	Yield (%)	Time (min)	Solvent	References
Al-MCM-41	refluxing	19	480	toluene	1
H3PW12O40·nH2O	refluxing	85	480	toluene	1
H3PMo12O40·nH2O	refluxing	78	480	toluene	1
H4SiW12O40·nH2O	refluxing	72	480	toluene	1
HM	refluxing	23	480	toluene	1
Hβ	refluxing	19	480	toluene	1
HY	refluxing	16	480	toluene	1
HZSM-5	refluxing	14	480	toluene	1
20 wt.%HPW/MCM-41	refluxing	66	480	toluene	1
30 wt.%HPW/MCM-41	refluxing	55	480	toluene	1
Aniline hydrochloride	Microwave	91	3	Solvent-free	4
Without catalyst	heating	93	3	water	–

Ajaikumar , S. and Pandurangan , A. 2008 . HPW and supported HPW catalyzed condensation of aromatic aldehydes with aniline: Synthesis of DATPM derivatives . J. Mol. Catal. A: Chem. , 286 : 21 – 30 .

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Guzmán-Lucero , D. , Guzmán , J. , Likhatchev , D. and MartÍnez-Palou , R. 2005 . Microwave-assisted synthesis of 4,40-diaminotriphenylmethanes . Tetrahedron Lett. , 46 : 1119 – 1122 .

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