Benzylation vapor phase

Under typical Hquid-phase chlorination conditions the maximum conversion to benzyl chloride of about 70% is reached after reaction of about 1.1 moles of chlorine per mole of toluene (39). Higher yields of benzyl chloride have been claimed 80% for low temperature chlorination (40) 80—85% for light-catalyzed chlorination in the vapor phase (41) and 93.6% for continuous chlorination above 125°C in a column packed with glass rings (42). 

Kiguchi, M. (1993). Chemical modification of wood surfaces by etherification. IV. Benzylation with solvent-dilution and vapor-phase methods. Mokuzai Gakkaishi, 39(1), 80-85. 

Photolytic. A n-hexane solution containing /n-xylene and spread as a thin film (4 mm) on cold water (10 °C) was irradiated by a mercury medium pressure lamp. In 3 h, 18.5% of the p-xylene photooxidized into p-methylbenzaldehyde, p-benzyl alcohol, p-benzoic acid, and p-methylacetophenone (Moza and Feicht, 1989). Glyoxal and methylglyoxal were produced from the photooxidation of p-xylene by OH radicals in air at 25 °C (Tuazon et al., 1986a). The rate constant for the reaction of p-xylene and OH radicals at room temperature was 1.22 x lO " cmVmolecule-sec (Hansen et al., 1975). A rate constant of 7.45 x 10 L/molecule-sec was reported for the reaction of p-xylene with OH radicals in the gas phase (Darnall et al, 1976). Similarly, a room temperature rate constant of 1.41 x 10 " cm /molecule-sec was reported for the vapor-phase reaction of p-xylene with OH radicals (Atkinson, 1985). At 25 °C, a rate constant of 1.29 x lO " cmVmolecule-sec was reported for the same reaction (Ohta and Ohyama, 1985). 

The purity of the Dess-Martin periodinane (2) was assayed by treatment of 2 (1 equiv) with an excess of benzyl alcohol (2 equiv) in methylene chloride (CH2CI2) followed by analysis of the reaction mixture for benzaldehyde by capillary vapor phase chromatography (15-m fused silica capillary column, Durawax DX3 stationary phase, 120°C). After correction for response factors, the purity was established to be >95%. 

Marlotherm Heat-Transfer Fluids. Two heat-transfer fluids are manufactured by Hbls America Madotherm S is a mixture of isomeric dibenzylbenzenes intended for liquid-phase systems, and Marlotherm L is a mixture of benzyl toluenes that are suitable for both liquid- and vapor-phase applications. Marlotherm L can be pumped readily at temperatures as low as —50° C and can be used in vapor-phase systems at temperatures from 290—350°C. The low temperature characteristics of Marlotherm enable it to be used in processes involving both heating and cooling. 

More recently, Kiguchi reported benzylation of wood particles with the solvent dilution and vapor phase methods for reducing the amount of benzyl chloride in the etherification agent [12]. In the vapor phase benzylation below the boiling point of benzyl chloride, greatly thermoplasticized particles could be produced after 2-4 h at 140°C. However, in the solvent dilution method, higher reaction temperatures and longer reaction times than those in the ordinary liquid phase method were found to be necessary to obtain the thermoplasticized particles. 

Vapor Phase Benzylation. It has generally been concluded that vapor phase... 

Figure 24 Thermal softening curves of vapor phase benzylated particles, h, Vapor benzylation time (hour) at 140°C.

Iron and copper phthalocyanines catalyze the isomerization of dimethyl maleate to dimethyl fumarate in the vapor phase at 300°C. No catalytic activity was observed in solution (338). Magnesium and zinc phthalocyanines catalyze the polymerization of methyl methacrylate when illuminated (Xm 600 m/i) (197). Manganous phthalocyanine (88) and ferrous phthalocyanine (59) catalyze the aerial oxidation of benzyl alcohol to benzaldehyde. The catalytic oxidation of ascorbic acid, using magnesium and copper derivatives, is light-sensitive (190, 310). a-Tetralin is catalytically oxidized, in the presence of the magnesium, zinc, or iron complexes, to a-tetralone, the reaction being chemiluminescent (60, 61,158,169, 371). The oxidation of luminol to 5-aminophthalazine-l,4-dione, catalyzed by iron phthalocyanine, is also chemiluminescent (61, 345, 361). 

Vapor phase thermolysis of [6]paracydophane (la) (Structures 1) yielded spiro triene 77 (Structures 10) as the major product via homolytic cleavage of one of the benzylic bonds [5b, 10]. FVP of [5.2.2]propelladiene (21a) (Structures 3) afforded spiro compound 78 (Structures 10) by similar homolysis of intermediate [5]paracyclophane (2a) (Structures 1) [61]. In contrast, the reverse reaction, FVP of spiro trienes, was successfully used for the preparation of [n]paracy-clophanes with n = 7 and 8 [62]. Pyrolysis of spiro tetraene 79, however, did not give [7]paracycloph-3-ene (80) (Structures 10) [63]. Evidently, [7]paracy-clophane is the borderline case with regard to the thermodynamic stabilities between the bridged aromatic compound and the spiro triene isomer. 

Belter RK (2011) High temperature vapor phase reactions of nitrogen trifluoride with benzylic substrates. J Fluor Chem 132(5) 318-322... 

Mahyari M, Laeini MS, Shaabani A. Aqueous aerobic oxidation of alkyl arenes and alcohols catalyzed by copper(II) phthalocyanine supported on three-dimensional nitrogen-doped graphene at room temperamre. Chem Commun. 2014 50 7855-7857. Kumar A, Kumar VP, Kumar BP, KomandurW, Chary VR. Vapor phase oxidation of benzyl alcohol over gold nanoparticles supported on mesoporous Ti02- Catal Lett. 2014 144 1450-1459. 

For bipolar organic liquids, especially for hydrogen-bonding liquids such as alcohols and amines, the tendency to orient in the liquid phase, due to these highly directional intermolecular attractions, is greatly increased by this intermolecular interaction. We can see the effect of this in the significantly larger entropies of vaporization of bipolar chemicals, like aniline, phenol, benzyl alcohol, or ethanol (Table 4.2). 

Quite a number of workers have examined specific aspect of the direct photolysis of substituted benzenes and, although the mechanisms are not fully understood, some important conclusions have been reached. Hentz and Burton examined the photolysis of toluene, ethyl benzene and mesitylene in both liquid and vapor states using a medium-pressure mercury lamp. They concluded that the gas-phase products, hydrogen, methane and ethane, were formed with a quantum yield of about 10 , while polymer formation was much more important. At 150 °C hydrogen was the most important gas-phase product except for the case of ethyl benzene in the vapour, where both methane and ethane were more important than hydrogen. Porter and Wright have shown by flash photolysis that benzyl radicals are formed in the photolysis of toluene and ethyl benzene and have observed the absorption spectrum of the benzyl radical. 

Typical calculated T-valucs for different types cf carbon atoms are as follows methyl radical, 1.73 r-position cf a benzyl radical. 1.04 appositions in quinodlDetbane which is apparently stable in the vapor State but which polymerizes rapidly in condensed phases, 0.92 (singlet state) [Pg.128]

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