Benzyl decomposition

SuIfona.tlon, Sulfonation is a common reaction with dialkyl sulfates, either by slow decomposition on heating with the release of SO or by attack at the sulfur end of the O—S bond (63). Reaction products are usually the dimethyl ether, methanol, sulfonic acid, and methyl sulfonates, corresponding to both routes. Reactive aromatics are commonly those with higher reactivity to electrophilic substitution at temperatures > 100° C. Tn phenylamine, diphenylmethylamine, anisole, and diphenyl ether exhibit ring sulfonation at 150—160°C, 140°C, 155—160°C, and 180—190°C, respectively, but diphenyl ketone and benzyl methyl ether do not react up to 190°C. Diphenyl amine methylates and then sulfonates. Catalysis of sulfonation of anthraquinone by dimethyl sulfate occurs with thaHium(III) oxide or mercury(II) oxide at 170°C. Alkyl interchange also gives sulfation. 

Riboflavin forms fine yellow to orange-yeUow needles with a bitter taste from 2 N acetic acid, alcohol, water, or pyridine. It melts with decomposition at 278—279°C (darkens at ca 240°C). The solubihty of riboflavin in water is 10—13 mg/100 mL at 25—27.5°C, and in absolute ethanol 4.5 mg/100 mL at 27.5°C it is slightly soluble in amyl alcohol, cyclohexanol, benzyl alcohol, amyl acetate, and phenol, but insoluble in ether, chloroform, acetone, and benzene. It is very soluble in dilute alkah, but these solutions are unstable. Various polymorphic crystalline forms of riboflavin exhibit variations in physical properties. In aqueous nicotinamide solution at pH 5, solubihty increases from 0.1 to 2.5% as the nicotinamide concentration increases from 5 to 50% (9). 

Esters derived from the primary alcohols are the most stable and those derived from the tertiary alcohols are the least stable. The decomposition temperature is lower in polar solvents, eg, dimethyl sulfoxide (DMSO), with decomposition occurring at 20°C for esters derived from the tertiary alcohols (38). Esters of benzyl xanthic acid yield stilbenes on heating, and those from neopentyl alcohols thermally rearrange to the corresponding dithiol esters (39,40). The dialkyl xanthate esters catalytically rearrange to the dithiol esters with conventional Lewis acids or trifluoroacetic acid (41,42). The esters are also catalytically rearranged to the dithiolesters by pyridine Ai-oxide catalysts (43) ... 

Benzyl chloride undergoes self-condensation relatively easily at high temperatures or in the presence of trace metallic impurities. The risk of decomposition during distillation is reduced by the use of various additives including lactams (43) and amines (44,45). Lime, sodium carbonate, and triethylamine are used as stabilizers during storage and shipment. Other soluble organic compounds that are reported to function as stabilizers in low concentration include DMF (46), arylamines (47), and triphenylphosphine (48). 

Treatment of 7V-benzyl-l,2-benzisoxazolin-3-one with base produced a benzoxazine-4-one (see Scheme 88). The base catalyzed rearrangement of the 2-methyl-3-phenyl-l,2-benzoisoxolium salt to an oxazine is believed to proceed via a similar intermediate (67AHC(8)277). A number of other decompositions could possibly proced via this proposed route (74HCA376, 67AHC(8)277), which has also been postulated for the rearrangement of a variety of isoxazolium salts, e.g. the conversion of (200) into (202) (Section 4.16.3.3.2(i)(b)). 

Diaziridine, 3-benzyl-1,3-dimethyl-inversion, 7, 7 Diaziridine, 1,2-dialkyl-reaction with iodides, 7, 217 thermal decomposition, 7, 217 Diaziridine, dibenzoyl-rearrangement, 7, 214 Diaziridine, 3,3-dimethyl-Raman spectra, 7, 202 Diaziridine, fluoro-synthesis, 7, 232 Diaziridines acylation, 7, 213 from azomethines, 7, 231 calculations, 7, 198 from chloramine, 7, 230 cycloaddition reactions, 7, 28 electron diffraction, 7, 19 199 c/s-fused NMR, 7, 201 hydrolysis, 7, 216 inversion stability, 7, 200... 

Imidazole, 2-deutero-l, 4-dimethyl-photolysis, 5, 377 Imidazole, 2,4-dialkyl-benzylation, 5, 388 Imidazole, 4,5-dialkyl-synthesis, 5, 481, 482 Imidazole, 1-dialkylphosphoryl-decomposition, 5, 455 Imidazole, 1,2-diamino-reactions... 

Benzyioxycarbonyi chioride (Cbz-Ci, benzyi cbioroformate) [501-53-1] M 170.6, b 103 /20mm, d 1.195, n 1.5190. Commercial material is better than 95% pure and may contain some toluene, benzyl alcohol, benzyl chloride and HCl. After long storage (e.g. two years at 4 , Greenstein and Winitz [The Chemistry of the Amino Acids Voi 2 p. 890, J Wiley and Sons NY, 1961] recommended that the liquid should be flushed with a stream of dry air, filtered and stored over sodium sulfate to remove CO2 and HCl which are formed by decomposition. It may further be distilled from an oil bath at a temperature below 85 because Thiel and Dent [Annalen 301 257 1898] stated that benzyioxycarbonyi chloride decarboxylates to benzyl chloride slowly at 100 and vigorously at 155 . Redistillation at higher vac below 85 yields material which shows no other peaks than those of benzyioxycarbonyi chloride by NMR spectroscopy. LACHRYMATORY and TOXIC. 

Reactions of alcohols with sulfur tetrafluoride, because of decomposition and/or polymerization, usually do not give fluorinated products However, in the presence of a hydrogen fluoride scavenger like triethylamine or pyridine, even such sensitive substrates as benzylic alcohols [555], 2-phenylethanol, and 2-furylmethanol [554] can be fluorinated to give the expected fluoro derivatives (equation 73)... 

Whereas nitrosative decomposition of azidoalkanes such as hexyl, cyclohexyl, and benzyl azides with nitrosomum tetrafluoroborate gives only 0-5% yields of... 

To a stirred solution of 5.7 g (0.02 m) of 4-benzyloxy-2-ureidoacetophenone in 100 ml of chloroform is added 3.2 g (0.02 m) of bromine. The mixture is stirred at room temperature for about 45 minutes and the solution is concentrated in vacuo at 25°-30°C. The amorphous residue (hydrobromide selt of 4-benzyloxy-a-bromo-3-ureidoacetophenone) is dissolved in 80 ml of acetonitrile and 98 g (0.06 m) of N-benzyl-N-t-butylamine is added. The mixture is stirred and refluxed for 1.5 hours, then it is cooled toOt in an ice bath. Crystalline N-benzyl-N-t-butylamine hydrobromide is filtered. The filtrate is acidified with ethereal hydrogen chloride. The semicrystalline product is filtered after diluting the mixture with a large excess of ether. Trituration of the product with 60 ml of cold ethanol gives 4-banzyloxy-Of-( N-benzyl-N-t-butylamino)-3-ureidoacetophenone hydrochloride, MP 200°-221°C (decomposition). 

In studies on l-diazo-2-ketosulfones, Shioiri et at. found that the thermal decomposition of benzoyl(sulfonyl)diazomethanes 6 with benzyl alcohol in acetonitrile also gave two products.<82CPB526> One is the 4-sulfonyloxazole 7 whereas the other product 8 results from rearrangement and reaction with the alcohol. The ratio of products varies with the nature of the sulfone substituent with the benzyl group giving highest yields of oxazole (Scheme 5). 

Iron(II) alkyl anions fFe(Por)R (R = Me, t-Bu) do not insert CO directly, but do upon one-electron oxidation to Fe(Por)R to give the acyl species Fe(Por)C(0)R, which can in turn be reduced to the iron(II) acyl Fe(Por)C(0)R]. This process competes with homolysis of Fe(Por)R, and the resulting iron(II) porphyrin is stabilized by formation of the carbonyl complex Fe(Por)(CO). Benzyl and phenyl iron(III) complexes do not insert CO, with the former undergoing decomposition and the latter forming a six-coordinate adduct, [Fe(Por)(Ph)(CO) upon reduction to iron(ll). The failure of Fe(Por)Ph to insert CO was attributed to the stronger Fe—C bond in the aryl complexes. The electrochemistry of the iron(lll) acyl complexes Fe(Por)C(0)R was investigated as part of this study, and showed two reversible reductions (to Fe(ll) and Fe(l) acyl complexes, formally) and one irreversible oxidation process."" ... 

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