O-acyl-N-benzyllactamides are obtained in good yield by reaction of 4-benzyl-5-methyl-1,3-oxazolidine-2,4-diones with Grignards reagents and with lithium alkyls. Three alkanes and two ethers were oxidised with ozone in dichloromethane solution or in aqueous pH 3 suspension. Cyclodecane and cyclododecane were converted into the corresponding cycloalkanones. n-decane was converted into a mixture of isomeric n-decanones and carboxylic acids. An ester was formed from the ethers. Hence, one of the methylene groups of these substrates is generally converted into a carbonyl group. Some of these reactions have preparative value. The oxidation of naphthalene in dichloromethane or acetonitrile with excess ozone gives phthalic aldehyde, 2-formyl benzoic acid and phthalic anhydride. Small amounts of the (E)- and (Z)-isomer of 3-phenyl-(2-formyl)-propenal and are also observed in some cases. The reaction is faster in acetonitrile than in dichloromethane owing to the higher solubility of ozone in the former solvent. The reaction is faster on lowering the temperature because of the increase of the concentration of ozone in solution at lower temperature. With a 1:1 or a 1:2 naphthalene:ozone ratio high conversion and low selectivity for the anhydride is observed. The ozonation of cyclohexane in dichloromethane or acetonitrile gives cycloxexanone, cyclohexanol and acidic material. The influence of solvent, reactant concentration, amount of ozone, temperature, reaction time is studied. A reaction mechanism is proposed based on the results of a simulation of the reaction energetics. The ozonation of N-phenylmorpholine in dichloromethane or acetonitrile produced a lactame and a diformylderivative. These products derive from the attack of ozone at the heterocyclic ring. The reaction mechanism has been investigated by DFT calculations which show that the reaction occurs through the insertion of ozone at the carbon-hydrogen bond of a methylenic group of the morpholine ring. The regioselectivity is due to the to the significantly lower energy barrier calculated for the attack of ozone in α to nitrogen than in α to oxygen. Also, the energy barrier decreases with increasing the polarity of the solvent, accounting for the higher reaction rate observed for the reaction carried out in acetonitrile than in dichloromethane. The ozonation of trans- and cis-decalin in dichloromethane or acetonitrile gives the corresponding 9-hydroxydecalinns, 2- and 3-decalones and acidic material. The influence of solvent, reactant concentration, amount of ozone, temperature, reaction time is studied. A reaction mechanism is proposed based on the results of a simulation of the reaction energetics. The N,N bis(salicylidene)ethylenediaminocobalt(II) catalysed oxidative carbonylation of para-substituted aromatic primary amines at 100 °C in methanol gives carbamates in high yields. In presence of excess dimethylamine also N-aryl-N’,N’-dimethylureas are formed. In methylene chloride moderate yields in isocyanate are obtained. 1-methylbenzylamine gives the carbamate and the urea in high yield. i-propylamine gives only the urea. An α-aminoalcohol gives a 1,3-oxazolidin-2-one. Aliphatic secondary amines react faster and give carbamates in methanol and ureas in methylene chloride. The turnover frequency is also measured in two cases.
(2009). Sustainable procedures in organic synthesis. (Tesi di dottorato, Università degli Studi di Milano-Bicocca, 2009).
|Data di pubblicazione:||11-dic-2009|
|Titolo:||Sustainable procedures in organic synthesis|
|Settore Scientifico Disciplinare:||CHIM/06 - CHIMICA ORGANICA|
|Scuola di dottorato:||Scuola di dottorato di Scienze|
|Corso di dottorato:||SCIENZE CHIMICHE - 18R|
|Citazione:||(2009). Sustainable procedures in organic synthesis. (Tesi di dottorato, Università degli Studi di Milano-Bicocca, 2009).|
|Parole Chiave:||Nucleophilic additions, ring opening, Grignard reactions, lithium alkyls, 1,3-oxazolidine-2,4-dione, Ozone, Oxidation, Cyclohexane, Cyclohexanone, Cyclohexanol, Ab initio calculations, activation energy, N-phenylmorpholine, Lactame, Chemical Synthesis, Naphthalene, Phthalic anhydride,Alkane oxygenation, ether oxygenation, metal-free oxidation, decalins.|
|Appare nelle tipologie:||07 - Tesi di dottorato Bicocca post 2009|