Acid-Catalyzed Synthesis

Acid-Catalyzed Syntheses [of Organic Fluorine Compounds] ... 

Under the conditions of the acid-catalyzed syntheses of alkyl polyglycosides, secondary products, such as polydextrose [26,27], ethers, and colored impurities. 

Acid-catalyzed synthesis, dialkyl peroxides, 351-8, 712 Acidity value (ACV)... 

Table 11 Lewis acid-catalyzed synthesis of carba-artemisinins 142...

Acid-Catalyzed Synthesis. - 3.2.1 The Fundamentals. Homogeneous acid catalysts, such as sulfuric acid, phosphoric acid, hydrochloridric acid, organo sulfonic acids and others, can be used to catalyze the transesterification of TGs and the esterification of FFAs to produce biodiesel type monoesters. Nevertheless, because the acid-catalyzed transesterification is about 3 orders of magnitude slower than the alkali-catalyzed reaction for comparable amounts of catalyst, base catalysts have received the most attention in both the academic and industrial sectors. In addition, the corrosiveness of strong liquid acids and... 

Table 9 Reaction conditions used by Zhang et al. in the acid-catalyzed synthesis of biodiesel from waste cooking oif" ...

Scheme 80 Lewis acid-catalyzed synthesis of trans-P-lactams...

Scheme 7 Acid-catalyzed synthesis of meso-substituted tra s-A2B-corroles.

Scheme 91 Acid-catalyzed synthesis of raeso-substituted 21-oxa or 21-thia porphyrins.

Scheme 5. Lewis acid-catalyzed synthesis of bis-THF alcohol 11.

Thiols can be prepared by a variety of methods. The most-utilized of these synthetic methods for tertiary and secondary thiols is acid-catalyzed synthesis for normal and secondary thiols, the most-utilized methods are free-radical-initiated, alcohol substitution, or halide substitution for mercaptoalcohols, the most-utilized method is oxirane addition and for mercaptoacids and mercaptonitriles, the most-utilized methods are Michael-type additions. 

Acid-Catalyzed Synthesis. The acid-catalyzed reaction of alkenes with hydrogen sulfide to prepare thiols can be accomplished using a strong acid (sulfuric or phosphoric acid) catalyst. Thiols can also be prepared continuously over a variety of solid acid catalysts, such as zeolites, sulfonic acid-containing resin catalysts, or aluminas (22). The continuous process is utilized commercially to manufacture the more important thiols (23,24). The acid-catalyzed reaction is commonly classed as a Markownikoff addition. Examples of two important industrial processes are 2-methyl-2-propanethiol and 2-propanethiol, given in equations 1 and 2, respectively. 

Fig. 13.113. Boric acid catalyzed synthesis of Solvent Green 3.

Scheme 4. The acid-catalyzed synthesis of cucurbituril 20 [55,56] displays all of the hallmarks of a product-directed self-assembly. The product is obtained from urea, glyoxal, and formaldehyde through the intermediacy of the glycoluril 19...

Fig. 10. Co-operative asymmetric Brpnsted acid catalyzed synthesis of isoquin-uclidines...

The gas phase acid-catalyzed synthesis of pyridines from formaldehyde, ammonia and an alkanal is a complex reaction sequence, comprising at least two aldol condensations, an imine formation, a cyclization and a dehydrogenation (9). With acetaldehyde as the alkanal, a mixture of pyridine and picolines (methylpyridines) is formed. In comparison with amorphous catalysts, zeolites display superior performance, particularly those with MFI or BEA topology. Because formation of higher alkylpyridines is impeded in the shape-selective environment, the lifetime of zeolites is much improved in comparison with that of amorphous materials. Moreover, the catalytic performance can be enhanced by doping the structure with metals such as Pb, Co or Tl, which assist in the dehydrogenation. 

The Paal-Knorr synthesis of furans as well as thiophenes and pyrroles has been carried out on solid support and a library of heterocyclic compounds has been prepared <2003SL711>. It has been shown that the acid-catalyzed synthesis of 2,3>4-substituted furans from 1,4-diketones can be assisted by microwave irradiation <20040L389>. 

Figure 20 Acid-catalyzed synthesis of cyclotriveratrylene (CTV) and cyclotetraveratrylene (CTTV).

A number of authors have reported the acid-catalyzed synthesis of five-membered heterocycles containing nitrogen and oxygen (oxazoles) from oxiranes, with acetonitrile and benzonitrile. The stereochemistry of the reaction has also been dealt with in Refs, 997-999. By the reaction of oxiranes with RSCN in the presence of BF3, alkylthiooxazolines have been obtained (Eq. 205). ... 

Until recently, the acid-catalyzed synthesis of calixarenes was limited to the calixresorcarenes. A kinetic and molecular modeling study of the acid-catalyzed reaction of acetaldehyde and resorcinol comes to the conclusions that... 

Cejka, J. and Wichterlova, B. 2002. Acid-catalyzed synthesis of mono- and dialkyl benzenes over zeolites active sites, zeolite topology, and reaction mechanisms. Catal. Rev. 44 375-421. 

Cejka, J. Wichterlova, B. Acid-catalyzed synthesis mono-... 

Sulfuric acid catalyzed synthesis of cellulose nitrate. The product will contain a mixture of mono (p subscript), di (q subscript), and tri (r subscript) substituted repeat units that will appear in the polymer backbone in random order, p + q + r m... 

The relative rates of reaction between the hydrolysis, condensation, and polycondensation directly affect the type and quality of sol-gel produced. For instance, in base-catalyzed sol-gel synthesis, the rate of the hydrolysis reaction is much slower than the polycondensation step, which tends to form a polymeric structure that is highly branched with relatively large particles. In contrast, in acid-catalyzed sol-gel synthesis, the rate of the hydrolysis reaction is much faster than the polycondensation step, which favors the formation of linear polymers. This also tends to form much smaller particles that the gel is composed of, which results in materials with much higher porosities and higher surface areas than is formed with sol-gels formed in base-catalyzed reactions. Therefore, acid-catalyzed synthesis tends to produce materials that have properties that are preferable for microfluidic applications. 

Scheme 3.40 Enantioselective Bronsted acid catalyzed synthesis of isoquinuclidines...

Mohammadpoor-Baltorka, I., Moghadama, M., Tangestaninejad, S., Mirkhania, V., Zolfigolb, M.A. and Hojatia, S.F. 2008. SUica sulfuric acid catalyzed synthesis of benzoxazoles, benzimidazoles and oxazolo[4,5-h]pyridines under heterogeneous and solvent-free con-dihons. J. Iran. Chem. Soc. 5 S65-S70. 

Nazeruddin, G.M., Pandharpatte, M.S. and Mulani, K.B. 2011. Heterogeneous catalyst Silica sulfuric acid catalyzed synthesis of 9, 10-dihydro-12-aryl-87f-benzo[a]xan-thenes-ll(12//)-one derivatives under solvent free conditions. Ind. J. Chem. 50(B) 1532-1537. 

Acid-catalyzed synthesis of quinolines from primary aromatic amines and a,p-unsaturated carbonyl compounds. When the latter are prepared in situ from two molecules of aldehyde or an aldehyde and methyl ketone, the reaction is known as the Beyer method for quinolines ... 

Mulik S, Sotiriou-Leventis C, Leventis N (2007) Time-Efficient Acid-Catalyzed Synthesis of Resorcinol-Formaldehyde Aerogels. Chem Mater 19 6138-6144. 

SCHEME 2.16 Proposed mechanistic pathway for a Brpnsted acid-catalyzed synthesis of 1,3-diamine. 

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