A systematic study of the synthesis conditions of blue and green ultramarine pigments via the reclamation of the industrial zeolite wastes and agricultural rice husks.

Discarded industrial zeolite waste and agricultural rice husks have caused a waste of resources. To achieve resource reuse, we proposed an economical method for the preparation of ultramarine pigments via the reclamation of industrial zeolite waste (ZW) and agricultural rice husks (RHs) or previously bio-charred rice husks (BRHs). The optimal blue and green pigments were synthesized by solid state reaction of mixtures of BRH/ZW/Na2CO3/S with mass ratios of 1:2:1:1.5 and 2:2:7:3, respectively, and using a two-step calcination process with a first stage at 500 and a second stage at 800 °C. Furthermore, the blue and green pigments were also obtained using directly RH (instead of BRH) as raw material, but this time with RH/ZW/Na2CO3/S mass ratios of 1:2:2:3 and 1:2:7:3.5 and with first-stage and second-stage calcination temperatures of 400 and 800 °C. This was done to reduce additional chemical reactions (e.g., BRH derived from the pyrolysis of RH). The XRD, FT-IR, Raman, and SEM results suggest that the synthetic blue and green pigments have the sodalite structure containing S3- and S2- radicals. The synthetic green pigment using RH as raw material had the best acid resistance. Additionally, the synthesis of blue and green ultramarine pigments via the reclamation of the industrial zeolite wastes and agricultural rice husks can reduce the costs of the production process.

A concise and efficient total synthesis of α-mangostin and ß-mangostin from Garcinia mangostana.

The concise, efficient synthesis of alpha-mangostin is described in eight simple steps with 8.3% overall yield. Highlights include a practical approach to construct the isopentene groups and other diverse groups at C-2 and C-8 of the xanthene skeleton through Claisen rearrangement and Wittig reaction. Meanwhile the first total synthesis of beta-mangostin is presented with a similar approach.