Isopropanol base catalyzed

Literature reports on diazaquinones derived from o-benzoquinone are very rare. Compound 74 was suggested to be a common intermediate formed during heating of 2,5-bis(diazo)-3,4-diketoadipate 73 with isopropanol and with various bases (76T269). Direct reduction of the intermediate with isopropanol provided pyridazine 75. A base-catalyzed benzilic acid rearrangement of 74 followed by decarboxylation of 76 afforded pyrazole 77 (Scheme 18). 

Okamura and coworkers151 studied the base catalyzed Diels-Alder reactions between 3-hydroxy-2-pyrone (224) and chiral l,3-oxazolidin-2-one based acrylate derivatives. Catalysis of the reaction between 224 and 225 by triethylamine gave fair to good de values, somewhat dependent on the solvent system used (equation 63, Table 7). Addition of 5% of water to the solvent isopropanol, for example, increased the de of the endo adduct 226 substantially. When the amount of water was increased, however, the triethylamine catalyzed reaction became less endo and diastereofacially selective, a small amount of exo 227 being obtained. Replacing triethylamine by the chiral base cinchonidine also improved the de, but now independently of the solvent system used. 

The results in Figures 1 and 2 could have important bearing on the observed catalytic behavior of this system. The diffusivity of propene, the product of the acid-catalyzed dehydration of isopropanol, is seen to be more than one order of magnitude larger than that of acetone, the product of the base-catalyzed reaction. If both reactions occur in parallel, the difference in product diffusivities could lead to a transport-promoted output of the acid-catalyzed product if the process is diffusion limited. 

Figure 20 shows the diffusivities of isopropanol, acetone and propene under the conditions of single-component adsorption on zeolite Na-X [170]. All three compounds are involved in a well-established test reaction to discriminate between acid and basic zeolites [171,172] Isopropanol is dehydrated to propene on acid catalysts, while it is dehydrogenated to acetone on basic catalysts. Figure 20 shows that the diffusivity of propene, i.e. of the product of the acid-catalyzed reaction is more than one order of magnitude larger than the diffusivities of the reactant (isopropanol) and of the product (acetone) of the base-catalyzed reaction. Hence, if the acid- and base-catalyzed reactions both were to occur in parallel, the difference in... 

Hydrolysis of Nylon 6,6 and Nylon 4,6 The depolymerization of nylon 6,6 and nylon 4,6 involves hydrolysis of the amide linkages, which are vulnerable to both acid- and base-catalyzed hydrolysis. In a patent granted to the DuPont Company in 1946, Myers [33] described the hydrolysis of nylon 6,6 with concentrated sulfuric acid, which led to the crystallization of adipic acid from the solution. Hexamethylene diamine (HMDA) was recovered from the neutralized solution by distillation. In a later patent assigned to the DuPont Company by Miller [34], a process was described for hydrolyzing nylon 6,6 waste with aqueous sodium hydroxide in isopropanol at 180°C and 2.2 MPa pressure. After distillation of the residue, HMDA was isolated and on acidification of the aqueous phase, adipic acid was obtained in 92% yield. Thorbum [35] depolymerized nylon 6,6 fibers in an inert atmosphere at what was reported to be a supeiatmospheric pressure of up to 1.5 MPa and at a temperature in the range of 160-220°C in an aqueous solution containing at least 20% excess equivalents of sodium hydroxide. 

In a study by Xu et al. [50], introduction of Cs via solid-state ion exchange was monitored by XRD and TGA/DTA. The Cs-BETA catalyst easily obtained by SSIE was found to have a rather high d ee of exchange, viz., 94%, and possess a high activity in base-catalyzed dehydrogenation of isopropanol (vide supra). 

Titrimetric analysis is a classical method for generating concentration-time data, especially in second-order reactions. We illustrate with data on the acetylation of isopropanol (reactant B) by acetic anhydride (reactant A), catalyzed by A-methyl-imidazole. The kinetics were followed by hydrolyzing 5.0-ml samples at known times and titrating with standard base. A blank is carried out with the reagents but no alcohol. The reaction is... 

A series of chiral N,S-chelates was synthesized as ligands for the iridium(l)-catalyzed reduction of ketones using either HCOOH/NEtj or isopropanol as hydrogen sources. The ligands were obtained by sulfoxidation of an (R)-cysteine-based aminosulfide, providing a diastereomeric ligand family containing a chiral sulfur... 

In a 1985 patent by Hoffmann-La Roche, the Wittig condensation was also the crucial step in assembling isotretinoin (1, Scheme 2). Under the optimized conditions, 1.03 equivalents of phosphonium salt 8 was condensed with 1 equivalent of hydroxybutenolide 9 in the presence of 1.25 equivalents of 2 N KOH in isopropanol at -30°C for 1 to 1.5 h. The product (91.5% total yield) consisted of 75.9% of 2-cis-4-cis-vitamin A acid (10) and 16.7% of isotretinoin (1). Without separation, the mixture of 10 and 1 was subjected to palladium-catalyzed isomerization conditions the mixture was heated at 50°C for 1 h in acetonitrile in the presence of 0.10 mol% of palladium(n) nitrate, four equivalents (based on palladium nitrate) of triphenylphosphine and 2... 

Two large-scale syntheses were reported by Quaedflieg et al. at Tibotec.31 Chiral synthon 20, obtained from ascorbic acid, was converted to a,p-unsaturated ester 21 in 92% yield and E/Z ratio was > 95 5. Michael addition of nitromethane to 21 was carried out with DBU as base to provide 22 in 80% yield and a syn/anti ratio of 5.7 1. A Nef reaction then converted 22 to a mixture of lactone 23 (major, 56%) (a/p = 3.8 1) and ester 24 (minor). The a-23 was obtained via recrystallization in isopropanol (37%), with high enantiomeric purity (> 99%). Isomerization of P-23 followed by recrystallization in isopropyl alcohol gave an additional 9% yield of a-23. It is interesting that most of 24 remained in the aqueous layer. Lithium borohydride reduction of a-23 followed by acid-catalyzed cyclization resulted in (-)-ll. 

Examples are the reduction of imines by isopropanol catalyzed by RuCl2(PPh3)3 in the presence of base,25 to give secondary amines and acetone, and the asymmetric... 

Pr )](C104)3 has been described.Attack of a glycine ester at the carbonyl centre occurs with fc = 14 M s at 25 °C. A second reaction is observed attributed to general acid-catalyzed removal of isopropanol from the conjugate base of the tetrahedral intermediate. 

Traditionally, the synthesis of symmetrical biaryls was routinely accomplished using the Ullmann reaction. Recently, Pd-catalyzed homocoupling of aryl halides has also been demonstrated to rival the utility of the Ullmann coupling. As illustrated in Scheme 21, using Pd(OAc)2 as the catalyst, K.C O. as the base in isopropanol [79], 3-bromoquinoline 58 was homocoupled to produce bis-quinoline 184 in 79% yield. Under the same reaction conditions, 2-chloroquinoline was homocoupled to give its corresponding dimer in 79% yield. 

New positive-type photoresist systems based on enzymatically synthesized phenolic polymers were developed [55]. The polymers from the bisphenol monomers exhibited high photosensitivity, comparable with a conventional cresol novolak. Furthermore, this photoresist showed excellent etching resistance. The oxidative polymerization of bisphenol-A proceeded by fungal peroxidase from Coprinus cinereus (CiP) in aqueous isopropanol [56]. CiP also catalyzed the oxidative... 

The catalysts based on silica fiberglass materials can be efficiently used in many gas-phase and Hquid-phase catalytic processes such as acid-catalyzed isopropanol dehydration reactions. To date, the acid-base properties of fiberglass materials, including the Brpnsted acidity, were not studied in detail. The lack of detailed studies could be due to the low specific surface area of fiber-... 

The acid/base property of various LDHs can be tested through the reactions of some probe organic chemicals. For example, isopropanol undergoes reaction (A) catalyzed by LDH-CO3 acting as a base (251,459-461) ... 

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