ABSTRACT
A highly efficient asymmetric inverse-electron-demand aza-Diels-Alder reaction of ß-trifluoromethyl α,ß-unsaturated ketone with cyclic N-sulfonyl ketimines catalyzed by (R)-3,3'-I2-BINOL-boron-complex was developed. A broad range of fused piperidine derivatives bearing stereogenic carbon containing CF3 motifs were prepared in high yields with excellent diastereo- and enantioselectivities (up to >20:1 dr, and >99% ee). This protocol had the characteristics of mild reaction conditions, high efficiency, and high stereoselectivity.
ABSTRACT
Ceramsite medium biological aerated filter (BAF) was used to treat the sewage containing di-(2-ethylhcxyl) phthalate (DEHP). The treatment efficiency under different empty bed contact time (EBCT) and temperatures was investigated and the major intermediate products of biodegradation of DEHP were analyzed via GC-MS. Results show that the removal rate of DEHP can be highly achieved at 90.3% under the conditions of 25 degrees C and 8 hours of empty bed contact time. The removal efficiency will be increased after raising temperature or EBCT. The EBCT plays the main role between two influencing factors. The biodegradation of DEHP in BAF is expressed in the first-order kinetics. The major intermediate products of biodegradation of DEHP are made up of mono-2-ethylhexyl phthalate( MEHP), bisethylhexyl phthalate (BEHP), dibutyl phthalate (DBP), dimethyl phthalate (DMP) and phthalic acid (PA). It is supposed that the possible pathway of the biodegradation of di-(2-ethylhcxyl) phthalate is that the long alkyl side-chain of DEHP may be cleavaged into a shorter and more straight one, then PA is formed after cleavaging the two ester bonds, and finally being oxidized into CO2 and H2O.
