Pale-yellow block crystals of 1 were formed. Yield 70% (based on the Zn).
Colorless needle crystals of 2 plus block crystals of 1 were formed, and 2 can be picked out handy form the mixture. Elemental analysis calcd (%)
Conversion of 2 to 1.
The crystals of compound 2 were ground and the resulting powder (0.05 mmol) was immersed in water (6 ml), and the pH value was adjust to 8.0 by NaOH solution (0.1 M) The resulting mixture was transferred into a 10 ml Teflon-lined stainless steel autoclave and kept at 150 °C for 72 h and then cooled to room temperature for 24 h. Pale yellow block crystals of 1 were obtained with a yield of 68%.