Aromatic esters, oxidation

Sulfinic esters, aromatic, by oxidation of disulfides in alcohols, 46, 64 Sulfonation ot d,l camphor to d,l-10-camphorsulfomc acid, 45,12 Sulfoxides, table of examples of preparation from sulfides with sodium metapenodate, 46,79 Sulfur dioxide, reaction with styrene phosphorus pentachlonde to give styrylphosphomc diclilonde, 46,... 

From the preceding discussion, it is easily understood that direct polyesterifications between dicarboxylic acids and aliphatic diols (Scheme 2.8, R3 = H) and polymerizations involving aliphatic or aromatic esters, acids, and alcohols (Scheme 2.8, R3 = alkyl group, and Scheme 2.9, R3 = H) are rather slow at room temperature. These reactions must be carried out in the melt at high temperature in the presence of catalysts, usually metal salts, metal oxides, or metal alkoxides. Vacuum is generally applied during the last steps of the reaction in order to eliminate the last traces of reaction by-product (water or low-molar-mass alcohol, diol, or carboxylic acid such as acetic acid) and to shift the reaction toward the... 

Baker s yeast catalyzed the regioselective cycloaddition of stable aromatic nitrile oxides ArCNO [Ar = 2,6-C12C6H3, 2,4,6-Me3C6H2, 2,4,6-(MeO)3C6H2] to ethyl cinnamate, ethyl 3-(p-tolyl)acrylate, and tert-butyl cinnamates (218). Reactions of dichloro- and trimethoxybenzonitrile oxides with all three esters proceeded regio- and stereoselectively to form exclusively alkyl tran.v -3,5-diary 1 -... 

Pr, Bu, Ph etc) to benzonitrile oxide are oxidized to trans-4-hydroxy-2-isoxazolines 10 by t-butyl hydroperoxide (94TL7493). A reversal of regiochemistry was observed in the reaction of aromatic nitrile oxides with derivatives of cinnamic acid the methyl ester gave a mixture of the esters 11 and 12 (R = OMe), in which the former predominated, while in the case of M,N-diethylcinnamide the amide 12 (R = NEt2) was the main product (94TL6473). 

By the simple procedure of passing dispersed air through a suspension of ff2-diethylbenzene, 1% chromia, and 4% calcium carbonate at 130° for 40 hours, a 50% yield of m-ethylacetophenone is obtained. Likewise, aromatic esters, acetophenones, and halogenated benzenes containing alkyl groups yield the corresponding keto esters, diketones, and halo ketones, respectively. Manganese dioxide catalyst has also been used. Tetralin can be oxidized to a-tetralone with dispersed air in the absence of a catalyst (56%). ... 

Photo-oxidative decarboxylation of indole-3-acetic acid in the presence of pyrimido[5,4-g]pteridine W-oxide has been described. Photoelimination of carbon dioxide has been observed in a variety of esters including aromatic esters, substituted l-naphthylmethyl alkanoates and ethyl a-oxocarboxylates,and is one pathway described in a review of the photochemistry of 2(3H)- and 2(5H) furanones.Ethylene, ethanol and carbon dioxide are the only... 

The carbonylation of aryl halides with alcohols and amines catalysed by palladium complexes with triphenylphosphine ligand is the convergent and direct route to the synthesis of aromatic esters as well as aromatic amides. Even though these palladium complexes are widely employed as the best catalytic system, those catalysts are difficult to separate and reuse for the reaction without further processing. The major drawbacks are oxidation of triphenylphosphine to phosphine oxide, reduction of palladium complex to metal and termination of the catalytic cycle. The phosphine-free, thermally stable and air resistant catalyst (1) containing a carbon-palladium covalent bond (Figure 12.3) has been found to be a highly selective and efficient catalyst for the carbonylation of aryl iodides.[1]... 

Another method for the preparation of 3-aryl-4//-l,2,4-oxadiazin-6(5.H )-oncs 4 is the reaction of aromatic nitrile oxides with ethyl esters of x-amino acids, which is thought to proceed via the esters of the A-(carboxymethyl)amide oximes discussed above. The nitrile oxides are generated from hydroxiinoyl chlorides7 and react in situ with the esters. If the esters are derived from optically active amino acids, optically active oxadiazinones are obtained.13... 

Poly(2,6-dimethyl-l,4-phenylene oxide) (PPO).— The photo-oxidation of this polymer has attracted some interest. Wandelt has found that the photoinitiated oxidation of PPO depends upon the mobility of one more unit in the polymer chain. A marked increase in the rate of photo-oxidation of the polymer occurs in the temperature range 45—60 °C, which corresponds with the j -relaxation phenomena. Chain mobility markedly controls the diffusion of oxygen. From detailed analysis of the products of PPO photo-oxidation the following reaction schemes have been proposed to account for hydroperoxide photolysis (Scheme 22) and quinone photoreaction with aromatic aldehydes to give aromatic esters, for example (16) (Scheme 23). The three chromophores are formed during... 

This newer analytical approach could effectively replace any need for reductive LCEC in the future, since it appears that most compounds already studied by reductive means can now be done by oxidative HPLC-hv-EC methods as well. This has Included compounds such as 1) organic nltro derivatives, C-nltro, 0-nitro, N-nitro, etc. 2) M-nltroso compounds, such as N-nltrosamlnes, N-nltroso amino acids, etc. 3) organothlophosphates, such as malathlon, parathion, ethion, etc. 4) aromatic esters and amides, such as benzamlde, vitamin B, alkyl benzoates, etc. 5) beta-lactams, such as penicillins and cephalosporins 6) mycotoxlns, such as vomltoxln or deoxynlvalenol ... 

The reaction of aromatic nitrile oxides with methanesulfonyl and benzylsulfonyl chloride in the presence of triethylamine yields the sulfonate esters of hydroxamoyl chlorides XII ( ). 

It has been shown (122) that aromatic polyesters degrade by a combination of Norrish I and Norrish II photolyses, with photo-oxidation playing an important part. Aromatic esters may also undergo an important photochemical reaction, known as the photo-Fries rearrangement (123). 

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