DMSO , as solvent

The classical procedure for the Wolff-Kishner reduction—i.e. the decomposition of the hydrazone in an autoclave at 200 °C—has been replaced almost completely by the modified procedure after Huang-Minlon The isolation of the intermediate is not necessary with this variant instead the aldehyde or ketone is heated with excess hydrazine hydrate in diethyleneglycol as solvent and in the presence of alkali hydroxide for several hours under reflux. A further improvement of the reaction conditions is the use of potassium tcrt-butoxide as base and dimethyl sulfoxide (DMSO) as solvent the reaction can then proceed already at room temperature. ... 

In DMSO as solvent and in the presence of nitrobenzene, aryl-de-diazoniation of the unsubstituted benzenediazonium ion leads mainly via meta substitution to 3-nitrobiphenyl, whereas in the case of the 4-nitrobenzenediazonium ion the formation of o- and -substituted products (2,4 -and 4,4 -dinitrobiphenyl) prevails (Gloor et al., 1972). 

The protected 5-amino-l-ribofuranosyl-4-(5-methyl-l,2,4-oxadiazol-3-yl)imidazole 58 (Equation 4) undergoes MHR to afford the 3-acetamidoimidazopyrazole 59 in dimethyl formamide (DMF) or DMSO as solvent at... 

The usual method of carrying out of Wolff-Kishner reduction is to heat a hydrzone in presence of a base at about 200°. But by using DMSO as solvent and potassium t.butoxide as base, the reduction can be carried at room temperature. 

Two groups [64, 184] have pursued the query of whether the base-induced dehy-drohalogenations of the 1-halocycloheptenes 468 generate also cycloheptyne besides 465. This does occur but the extent depends on the substrate (468a, b or c), the solvent and the kind of the base. Bottini et al. [184] treated 468a-c at 65 °C with KOtBu in THF and also in DMSO as solvent. In all cases, 474 was the major product, indi-... 

An unusually facile hydroxydemethoxylation reaction has been reported for 1-benzoyl-4-methoxynaphthalene. The use of 0-enriched hydroxide confirmed that reaction occurs by the NAr pathway rather than by cleavage of the oxygen to methyl bond. A related reaction is observed in 3-(4-methoxy-l-naphthoyl)indole derivatives. These results indicate the possibility of SnAt activation by a 4-carbonyl group the reaction is facilitated by use of a naphthyl ketone as substrate and DMSO as solvent. ... 

The rapid tautomerism due to the intermolecular exchange of protons between two N atoms in azoles can be slowed down by using DMSO as solvent to such an extent that even at room temperature different signals appear. 

Secondary aliphatic amines were found to give higher yields of thienothiophenes than did tertiary amines, which are weaker bases. A maximum ratio of thienothiophenes to thienothiopyrans of about 4 1 was achieved at 145° with diisopropylamine as cat yst and DMSO as solvent. Only thienothiopyrans were formed in DMF in the presence of the same catalyst The amines promote nucleophilic cyclization of Claisen rearrangement products into thienothiophenes. Since thienothiophenes are resistant to treatment with potassium t-butoxide in DMSO and thienothiopyrans form resinous products under these conditions, the method is a convenient route to pure thienothiophenes 35 and 42 in yields of up to 40%. ... 

Other nucleophiles, like cyanide, trifluoroethoxide and triethylamine, have been investigated in DMSO as solvent and Af-methylacridone was consistently formed as the final product, presumably via oxidation of a Af-methylacridone radical anion (42). Although this radical was never observed in EPR experiments, homolytic cleavage of a pinacol dianion is assumed to be likely (Scheme 29). 

Polarography [ELECTROANALYTICALTECHNIQUES] (Vol 9) analysis of peroxides [PEROXIDES AND PEROXIDE COMPOUNDS - ORGANIC PEROXIDES] (Vol 18) DMSO as solvent for [SULFOXIDES] (Vol 23)... 

DMSO) as solvent with the more soluble sodium thiocyanate, Jaunin found a cyclopropane (67) as product, carrying three phenyloxadiazolyl groups, R. He suggested that a carbene (66) intermediate must have formed from 64 with the solvent as shown in the sequence of Eq. (54). An ionic mechanism can be written, however. 

The generalizations in the following discussion are based on reports of reactions carried out under ideal conditions, i.e. liquid ammonia or DMSO as solvent, photostimulation rather than dark reactions, most appropriate nucleofuge, etc. The range of nucleophiles which can be used are itemized in Section 2.2.3, which also contains several extensive tables in which the range of substrates can be clearly seen. It must be noted, however, that reactions which proceed in high yield with one nucleophile may fail or proceed inefficiently with another if the nucleophile is incompatible with substituents on the aromatic substrate. 

During some couplings of nucleosides, promoted by dicyclohexylcarbodii-mide (DCC), Pfitzner and Moffatt.13 decided to try dimethyl sulfoxide (DMSO) as solvent. Instead of obtaining the expected couplings, they observed oxidation of alcohols to aldehydes and ketones. These oxidations were very remarkable, because at that time, on the nucleosides tested, no oxidants were known to be able to deliver efficiently the observed aldehydes and ketones. Furthermore, contrary to many other oxidants, no over-... 

The kinetics of the addition of aniline (PI1NH2) to ethyl propiolate (HC CCChEt) in DMSO as solvent has been studied by spectrophotometry at 399 nm using the variable time method. The initial rate method was employed to determine the order of the reaction with respect to the reactants, and a pseudo-first-order method was used to calculate the rate constant. The Arrhenius equation log k = 6.07 - (12.96/2.303RT) was obtained the activation parameters, Ea, AH, AG, and Aat 300 K were found to be 12.96, 13.55, 23.31 kcalmol-1 and -32.76 cal mol-1 K-1, respectively. The results revealed a first-order reaction with respect to both aniline and ethyl propiolate. In addition, combination of the experimental results and calculations using density functional theory (DFT) at the B3LYP/6-31G level, a mechanism for this reaction was proposed.181... 

The condensation of an aromatic nitro compound with a second reactant should have been performed in an aqueous solution with DMSO in the semi-batch mode. The nitro-compound is initially charged into the reactor with water and DMSO as solvent. Before the progressive addition of the second reactant had been started, the initial mixture was heated to the process temperatures of 60-70 °C. Then a failure of the cooling water system of the plant occurred. It was decided to interrupt the process at this stage and to maintain the mixture under stirring until the failure had been repaired. The feed of the second reactant was postponed and the jacket of the reactor had been emptied. 

Whereas the examples discussed so far proceed according to the iminium ion mechanism (A), amine-catalyzed additions of, e.g., ketones to nitroolefins are effected by intermediate enamine formation (B). List et al. were the first to report that L-proline catalyzes the addition of several ketones to nitroolefins (Scheme 4.23). Whereas both the yields and diastereoselectivity were high in DMSO as solvent, the ee did not exceed 23% [38]. A related study of this process by Enders and Seki resulted in identification of methanol as a superior solvent, and enantioselec-tivity up to 76% was achieved (Scheme 4.23) [39]. 

N-terminal L-proline, again in DMSO as solvent [40], In this study the maximum ee in the addition of acetone to trans-2-nitrostyrene was 31%. Alexakis and Andrey successfully employed the bis-pyrrolidine 52 as catalyst for the addition of aldehydes and ketones to trans-fi-nitrostyrene [41], whereas Barbas and Betancort [42] were able to perform the Michael addition of unprotected aldehydes to nitroolefins using the pyrrolidine derivative 53 as catalyst (Scheme 4.24). 

You are in charge of scaling up an asymmetric oxidation process for making 10 tpa (tons per annum) of a pharmaceutical intermediate which sells at 5000 ( 6750) per kg. The lab-scale reaction uses 2 mol% of a Ru-ligand complex as a catalyst and DMSO as solvent. List the factors you must consider when planning your scaleup operation. How would your list change if the product were a polymerization additive with a market price of 50 ( 67) per kg ... 

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