Acylation bimolecular aromatic

The heat of decomposition (238.4 kJ/mol, 3.92 kJ/g) has been calculated to give an adiabatic product temperature of 2150°C accompanied by a 24-fold pressure increase in a closed vessel [9], Dining research into the Friedel-Crafts acylation reaction of aromatic compounds (components unspecified) in nitrobenzene as solvent, it was decided to use nitromethane in place of nitrobenzene because of the lower toxicity of the former. However, because of the lower boiling point of nitromethane (101°C, against 210°C for nitrobenzene), the reactions were run in an autoclave so that the same maximum reaction temperature of 155°C could be used, but at a maximum pressure of 10 bar. The reaction mixture was heated to 150°C and maintained there for 10 minutes, when a rapidly accelerating increase in temperature was noticed, and at 160°C the lid of the autoclave was blown off as decomposition accelerated to explosion [10], Impurities present in the commercial solvent are listed, and a recommended purification procedure is described [11]. The thermal decomposition of nitromethane under supercritical conditions has been studied [12], The effects of very high pressure and of temperature on the physical properties, chemical reactivity and thermal decomposition of nitromethane have been studied, and a mechanism for the bimolecular decomposition (to ammonium formate and water) identified [13], Solid nitromethane apparently has different susceptibility to detonation according to the orientation of the crystal, a theoretical model is advanced [14], Nitromethane actually finds employment as an explosive [15],... 

A mechanism of action for the r-deficient 2-heteroaryl derivatives was postulated based upon the reaction of 6-(2-pyridyl)methylene penicillanic acid sulphone (28) with sodium methoxide (Scheme 6.14) [46]. Chen and co-workers proposed that after bimolecular interaction between the enzyme and (28), an aromatic acyl-enzyme ester (76) is obtained. This conjugated... 

The electrophile is usually produced by the reaction between a catalyst and a compound containing a potential electrophile (Eq. 15.3). The second-order nature of the reaction arises from the step shown in Equation 15.4 in which one molecule each of arene and electrophile react to give a cationic intermediate. The formation of this cation is the rate-determining step (rds) in the overall reaction the subsequent deprotonation of the cation (Eq. 15.5) is fast. The bimolecular nature of the transition state for the rate-limiting step and the fact that an electrophile is involved in attacking the aromatic substrate classifies the reaction as S 2 (Substitution Electrophilic Bimolecular). Experiments involving four different such reactions are given in this chapter Friedel-Crafts alkylation and acylation, nitration, and bromination. 

The Friedel-Crafts reaction we have discussed in this section is an intermolecular reaction between an aromatic compound and an acyl halide. However, if the acyl halide also contains an aromatic ring, an intramolecular reaction can easily occur. Such a unimolecular reaction is favored over a bimolecular reaction when the ring formed contains either five or six atoms. This is a Friedel-Crafts reaction in which the acyl chloride acylates the ortho position. 

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