Y-Phenyl X-benzoates

The kinetics of the aminolysis reactions of the a-effect nucleophiles hydrazine and hydroxyiamine with Y-phenyl X-benzoates (8) have been reported." The results demonstrated that the magnitude of the a-effect decreases with increasing electron-withdrawing ability of the acyl substituents. The authors propose that hydrazine stabilizes the transition state (9) by intramolecular H-bonding. ... 

The aminolysis of Y-phenyl X-benzoates by piperidine in 20 mol% DMS0-H20 at 25 °C proceeded, on the basis of a curved Brpnsted-type plot, via a zwitterionic tetrahedral intermediate with a change in the RDS the curvature centre of the plots was at p Ka = 6.4 regardless of the electronic nature of the substituent X in thebenzoyl moiety 27 The rates of aminolysis of a series of Y-phenyl benzoates by acylic secondary amines were compared with new results for similar reactions with Y-phenyl diphenylphosphi-nates (discussed further in the section Phosphates and Phosphinates). The results showed that the C=0 compounds were more reactive than the P=0 compounds 28... 

Recently, the PER of phenyl acetate and phenyl benzoate has been studied within zeolites of the faujasite and pentasil families, which are structurally very different. [277,278] It was found that for phenyl acetatet in faujasites X and Y, the predominating product is the ortho isomer, whereas in the pentasils ZSM-5 and ZSM-11, the preferred product is the para isomer. These differences have been explained taking into account the different sizes and shapes of the cavities and channels of the two families. The faujasites are made up of channels of 8 A diameter, leading to supercages of 13 A diameter, where the reaction is expected to occur, whereas the pentasils are made up of narrow channels of 6 A diameter. In the X and Y faujasites, the ortho position would be favored due to the restricted mobility, whereas in the channels of ZSM-5 and ZSM-11, there would be a shape limitation because the ortho isomer does not fit but the para isomer does (Table 15). With phenyl benzoate inside X or Y zeolites, the same... 

Ramamurthy and coworkers studied the photo-Fries rearrangement of phenyl acetate and phenyl benzoate and photo-Claisen rearrangement of allyl phenyl ether (Fig. 34) included in two types of zeolite (faujasites X and Y and pen-tasils ZSM-5 andZSM-11) [192], The photolysis was performed with the zeolite slurry in either hexane or iso-octane. One of the most remarkable observations is that the product distribution is altered within zeolites from that in isotropic solvent. Furthermore, while in solution, nearly a 1 1 mixture of ortho and para isomers 40 and 41 (Fig. 34) was obtained, within zeolites one is able to direct the photoreaction selectively toward either the ortho or the para products by conducting the reaction either within faujasites or pentasils, respectively (Fig. 34). 

---