Aromatics synthesis from methanol

The influence of the solvent was studied for the hydrolysis of 2-, 3- and 4-nitroacetanilide using an HY zeolite (Si/Al=30) as catalyst. From Table 1 it can be seen that the reaction rate was higher when a mixture of methanol-water (1 1) was used as solvent than with methanol or with water separately. The slower hydrolysis rate in water, when compared to methanol or to methanol-water, can be explained by the lower solubility of the aromatic amides. The hydrolysis in the presence of methanol could be due to the small amounts of water present in the commercial synthesis grade methanol used. While this is enough to accomplished the reaction, methanolysis cannot be ruled out. 

Recently, a novel and efficient synthesis of oxazoles from tosylmethyl isocyanide and carbonyl compounds has been discovered by van Leusen et al.ai Thus, 5-aryloxazoles are prepared in 57-91% yield by refluxing tosylmethyl isocyanide (24) and aromatic aldehydes in methanol in the presence of potassium carbonate. 

Structure promoters can act in various ways. In the aromatization of alkanes on Pt catalysts, nonselective dissociative reaction paths that lead to gas and coke formation can be suppressed by alloying with tin. This is attributed to the ensemble effect, which is also responsible for the action of alkali and alkaline earth metal hydroxides on Rh catalysts in the synthesis of methanol from CO/H2 and the hydroformylation of ethylene. It was found that by means of the ensemble effect the promoters block active sites and thus suppress the dissociation of CO. Both reactions require small surface ensembles. As a result, methanol production and insertion of CO into the al-kene are both positively influenced. 

Recent advances have shown zeolites are effective in catalysing the direct conversion of synthesis gas to motor fuels. The MTO (methanol-to-olefins) process converts MeOH to C2-C4 alkenes and is also catalysed by ZSM-5. The development of a gallium-modified ZSM-5 catalyst (Ga-ZSM-5) has provided an efficient catalyst for the production of aromatic compounds from mixtures of C3 and C4 alkanes (commonly labelled LPG). 

Natural gas and crude oils are the main sources for hydrocarbon intermediates or secondary raw materials for the production of petrochemicals. From natural gas, ethane and LPG are recovered for use as intermediates in the production of olefins and diolefms. Important chemicals such as methanol and ammonia are also based on methane via synthesis gas. On the other hand, refinery gases from different crude oil processing schemes are important sources for olefins and LPG. Crude oil distillates and residues are precursors for olefins and aromatics via cracking and reforming processes. This chapter reviews the properties of the different hydrocarbon intermediates—paraffins, olefins, diolefms, and aromatics. Petroleum fractions and residues as mixtures of different hydrocarbon classes and hydrocarbon derivatives are discussed separately at the end of the chapter. 

Among the wide variety of organic reactions in which zeolites have been employed as catalysts, may be emphasized the transformations of aromatic hydrocarbons of importance in petrochemistry, and in the synthesis of intermediates for pharmaceutical or fragrance products.5 In particular, Friede 1-Crafts acylation and alkylation over zeolites have been widely used for the synthesis of fine chemicals.6 Insights into the mechanism of aromatic acylation over zeolites have been disclosed.7 The production of ethylbenzene from benzene and ethylene, catalyzed by HZSM-5 zeolite and developed by the Mobil-Badger Company, was the first commercialized industrial process for aromatic alkylation over zeolites.8 Other typical examples of zeolite-mediated Friedel-Crafts reactions are the regioselective formation of p-xylene by alkylation of toluene with methanol over HZSM-5,9 or the regioselective p-acylation of toluene with acetic anhydride over HBEA zeolites.10 In both transformations, the p-isomers are obtained in nearly quantitative yield. 

For the total synthesis of mukonidine (54), the required arylamine 656 was obtained quantitatively from commercial 4-aminosalicylic acid (659) using diazomethane (559). However, for large-scale preparation, this transformation was better achieved with sulfuric acid and methanol (81). The reaction of the arylamine 656 with the iron-complex salt 602 provided the iron complex 660 in 87% yield. The high yield of C-C bond formation was ascribed to the high nucleophilicity of the ortho-amino position of the aromatic nucleus arising from the hydroxy group in the 3-position of the arylamine. The iron-mediated arylamine cyclization of the complex... 

---