Zheng Qiong

A Direct Synthesis of Aromatic Nitriles from Methylaromatic Compounds by Ammoxidation on DC-108 Catalyst

Abstract Aromatic nitriles were prepared from corresponding methylaromatic compounds by ammoxidation on DC-108 catalyst, giving 51-89% in yield. This method is simple and convenient without pollution.

Ammoxidation of substituted toluenes on silica-supported VPO catalysts

The ammoxidation of substituted toluenes to their corresponding nitriles over silica-supported vanadium phosphorus oxide (VPO/SiO2) catalysts has been studied. the effects of carrier silica, the addition of phosphorus, the substituents and the loadings have been discussed. Compared with unsupported VPO, the VPO/SiO2 catalysts have higher catalytic activity for ammoxidation of substituted toluenes and much lower reaction temperature. XRD shows that vanadium phosphorus oxides exist as amorphous phase and disperse to a high degree on the silica surface in 10% loading catalyst. When the loadings are over 10%, the crystalline α-VOPO4 would emerge, which would decrease the yield and selectivity. Additional phosphorus can form composite oxides with vanadia and play concerted catalytic function, which increase the selectivity of nitriles remarkably. Different substituents or same substituents on different positions have different influences because of the variant electronic stability of intermediates, the hindered accessibility of methyl group or the chemisorption state of the substrate molecule on the electrophilic catalyst surface.

3,4-dichlorotoluene ammoxidation to 3,4-dichlorobenzonitrile over VPO/SiO2 catalyst

Ammoxidation of 3,4-dichlorotoluene (DCT) to prepare 3,4-dichlorobenzonitrile (DCBN) over silica supported vanadium phosphorus oxide catalysts has been studied. On the VPO/SiO2 catalyst, the influence of the reaction temperature, the molar ratio of air/DCT, the molar ratio of NH3/DCT in the feed gas and the space velocity (v1) on the conversion, yield and selectivity was observed. The most appropriate reaction condition is: reactionT=673 K,n(DCT):n(NH3):n(air)=1:7:30 andv1=250 h−1. At this optimum reaction condition, the conversion of DCT is 97.8%; the molar yield of DCBN is 67.4%. It was found that the addition of element phosphorus can improve the yield of DCBN compared with VO/SiO2 catalyst.

A New Synthetic Routine for Preparation of 2,4-Dibromo-S-Fluorobenzoic Acid

Abstract A convenient and practical synthetic route for the preparation of 2,4-dibromo-5-fiuorobenzoic acid is described. The synthesis and characterization of two intermediates, 2,4-dibromo-5-fluorobenzonitrile and 2,4-dibromo-5-fluoro-benzamide. in this route have not been reported before.

Research on preparation of 2,4-Dichlorobenzonitrile by ammoxidation of 2,4-dichlorotoluene

A process for ammoxidation of 2,4 dichlorotoluene to prepare 2,4 dichlorobenzonitrile which is a key intermediate of organic synthesis was studied. Having appraised and screened catalysts on an apparatus of “microreactor chromatograghy”, the further experiments confirming the catalyst and finding the optimum technological conditions were carried out by using a fixed bed reactor made of quartz (30 mm inside diameter). The influence of temperature, the ratio of ammonia, the ratio of air and the space velocity of catalyst upon the conversion, molar yield and selectivity of the reaction were observed, respectively. Using catalyst of DC124, on the suitable conditions, the highest conversion is 98.1%, molar yield is 89.5%. The 2,4 dichlorobenzonitrile obtained is white sheet or needle crystal with the purity higher than 99%. The effect of two chlorine atoms at 2,6 or 2,4 position on the reaction is discussed based on the research of the ammoxidation of 2,6 dichlorotoluene and 2,4 dichlorotoluene.

Synthesis of 2,4-dibromo-5-fluorobenzonitrile

Abstract2,4-Dibromo-5-fluorobenzonitrile has been synthesized for the first time (81.5% yield). It may be used in synthesizing 2,4-dibromo-5-fluorobenzoic acid, the intermediates of fluoroquinolones. The ammoxidation procedure for preparation of the nitrile has been described in detail.