Theoretical Study On The Similar Friedel-Crafts Acylation Between PCl3 And Aromatic Compounds

The problem of catalyst deactivation encountered in the industrial production of Benzephosphorusdichloride(BPD)prepared the similar Friedel-Crafts acylation was studied.The catalysis and deactivation mechanism of the catalyst was studied by density functional theory.Different Lewis acid catalysts were screened to investigate the catalytic activity.In addition,the reactions between PCl3 and other substituted benzene were also investigated.The whole works are as follows:(1)With regard to the reaction of preparation of BPD by the similar Friedel-Crafts acylation,the complexes formed by anhydrous AlCl3,reactants and products were taken as research objects,and two kinds of complexes between AlCl3 and PCl3,BPD and the by-product diphenylphosphine chloride(DPC)were obtained.One is the coordination between AlC13 and Cl atoms(type A),and the other is the coordination between AICl3 and P atoms(type B).The formation of PCl3-AlCl3 and BPD-AlCl3 in the type A complex enables the P atom to attack the benzene ring with a relatively positive electrostatic potential,which contributes to the smooth progress of the reaction.With the increasing interaction intensity of PCl3-AlCl3 BPD-AlCl3 and DPC-AlCl3,it is gradually difficult to dissociate AlCl3 from the complexes.Once DPC-AlCl3 is formed,it is difficult to dissociate AlCl3,so the catalyst cannot be recycled.Thus,the reason why the catalyst could not be recycled was revealed.(2)In order to solve the problem of catalyst deactivation in the process of synthesis of BPD,the seed industry of Lewis acid catalyst was changed and its coordination properties were studied to find suitable catalysts.Six kinds of catalysts with certain catalytic activity were selected from more than 20 kinds of Lewis acid catalysts.By calculation,the catalytic activity of the six catalysts was as follows:AlCl3>InCl3>BiCl3>GaCl3>SbCl3>ZnCl2.The activation ability of these six catalysts on PCl3 was studied,and the minimum electrostatic potential of P+region in the activated complex molecule was obtained as following:AlCl3-PCl3>InCl3-PCl3>BiCl3-PCl3>GaCl3-PCl3>SbCl3-PCl3>ZnCl2-PCl3.(3)Seven substituted benzenes(R1=H,R2=CH3,R3=F,R4=Cl,R5=OCH3,R6=NO2,R7=CN)were selected as substrates,and the condensed Fukui function and the condensed double descriptor were calculated to explore the electrophilic substitution reactive sites of aromatic derivatives.The electrophilic reactive sites of the aromatic hydrocarbons with substituents-CH3,-F,-Cl,-OCH3 are the ortho-positions of the substituents,and the positional effect of the para-position is stronger than that of the ortho-position atoms;the nitro group and the cyano group are The meta positional substituent,the electrophilic substitution occurs at the meta atom.The interaction energy between different phenylphosphines and the complexes formed by the catalyst(AlCl3:BPD-R and AlCl3:DPC-R)were investigated.The results showed that the complexes corresponding to the electron-donating substituents R5-OCH3 and R2-CH3 had a strong stability.When the substituents were electron-absorbing groups,the stability of the complexes was weak.