Synthesis of 5,5ꢀ-Methylene-bis(Benzotriazole)
Experimental Section
163
Mps and bps are uncorrected. The purity of products was established on an Agilent 1100
HPLC. 1H NMR spectra were recorded in CDCl3 on a Bruker 400 (400 MHz) instrument
with TMS as an internal standard. Infrared spectra were obtained on a Shimadzu IR-408
instrument. All chemicals were reagent grade and available commercially. The elemental
analysis was performed on a Flash EA1112 instrument.
Methyl Nitrite (prepared just prior to use)
In a 1-L round-bottomed flask, fitted with a pressure equalizing addition funnel filled with
250 mL 12 M hydrochloric acid, and a gas tube in a well ventilated hood, was placed 172.5
g (2.5 mol) of sodium nitrite, 135 mL methanol, and 250 mL water. The temperature was
raised to 35◦C and hydrochloric acid was added dropwise over 2 hours. The methyl nitrite
evolved was passed through a water trap to remove acid and then bubbled through the
reaction mixture below via the gas tube.
5,5ꢀ-Methylene-bis(benzotriazole)
In a 5-L round-bottomed flask, fitted with a mechanical stirrer, and a gas tube in a well
ventilated hood, was placed 270.0 g (1.18 mol) of tetraaminodiphenylmethane, 4040 mL
methanol, and 440 mL of water under a nitrogen atmosphere. The temperature was raised
to 40◦C and methyl nitrite (152.5g, 2.5 mol, prepared above) was added through the tube
for about 2 hours while the temperature was kept at about 40◦C via water bath. When the
reaction was complete, the temperature was raised to 50◦C and the mixture was stirred for
another 20 min. to expel excess methyl nitrite. The mixture was then poured into 7 L water,
and the precipitated crystals were collected and dried in vacuo to afford 272.0 g (92%) of
the crude product as a pale red solid (HPLC > 98.5%), mp. 238–240◦C. 1H NMR (DMSO-
d6): δ 4.32 (2 H, s), 7.37 (2 H, d, J = 8.8 Hz), 7.80–7.86 (4 H, m), 15.6 (2 H, b).
An analytical sample was prepared by recrystallization from methanol, mp. 239–240◦C.7
Anal. Calcd. for C13H10N6: C, 62.39; H, 4.03; N, 33.58. Found: C, 62.58; H, 3.97;
N, 33.42.
Acknowledgments
We thank the National Natural Science Foundation of China (Grant No. 20602029) and
the Science and Technology Foundation of Zhejiang Province (Grant No. 2007C11014) for
financial support.
References
1. D. R. Clack and W. D. Philips, GB1514359 1978; Chem. Abstr., 89, 215412 (1978).
2. S. Bauer, EP268553 1988; Chem. Abstr., 110, 163601 (1988).
3. X. C. Yu, H. Gu and W. M. Xu, Org. Prep. Proced. Int., 38, 467 (2006).