Sodium catalytic acceleration

Sodium Amide or Sodamide, NaNH2. Wh crysts, mp 206.4° dissolves in liq NH3 and is vigorously hydrolyzed by HjO. Was first prepd ca 1810 by Gay-Lussac and Thenard by the action of NH3 gas on molten metallic Na heated to 300°. Can also be prepd by dissolving metallic Na in liq NH3 and then placing in the soln a a spiral of. Fe wire, which catalytically accelerates the otherwise very slow reaction Na + NH NaNH2 + H Mixts of sodamide with nitrates and chlorates expl when triturated (Ref 1, p 255)... 

When crystalline free sulfur is to be detected in a mixture with other solids, it can be extracted with carbon disulfide (compare page 433). After evaporation of the solvent, the sulfur in the residue can be converted into sodium thiosulfate by warming with a solution of sodium sulfite. The thiosulfate is revealed by using the sensitive test based on the catalytic acceleration ot the reaction 2 NaNg + Ig 2 Nal + 3 Ng (see page 453). 

Water Treatment. Sodium sulfite is an agent in the reduction of chlorine or oxygen in water. Dissolved oxygen in boiler water tends to enhance pitting and other types of corrosion. In boilers operated at below 4.82 MPa (700 psi), a residual concentration of 30 ppm of sodium sulfite is generally effective. Catalytic amounts of cobalt are often added to accelerate the reaction of oxygen with sulfite (321,322) (see Water, industrial water treatment). 

The second step, nucleophilic attack of an alcohol or phenol on the activated carboxylic acid RCOIm (carboxylic acid imidazolide), is usually slow (several hours), but it can be accelerated by heating[7] or by adding a base[8] [9] such as NaH, NaNH2, imidazole sodium (ImNa), NaOR, triethylamine, diazabicyclononene (DBN), diazabicycloimdecene (DBU), or /7-dimethylaminopyridine to the reaction mixture (see Tables 3—1 and 3—2). This causes the alcohol to become more nucleophilic. Sodium alcoholate applied in catalytic amounts accelerates the ester synthesis to such an extent that even at room temperature esterification is complete after a short time, usually within a few minutes.[7H9] This catalysis is a result of the fact that alcoholate reacts with the imidazolide very rapidly, forming the ester and imidazole sodium. 

The catalytic effect of quaternary ammonium salts in the basic liquid liquid two-phase alkylation of amines [1-3] is somewhat unexpected in view of the low acidity of most amines (pKfl>30). Aqueous sodium hydroxide is not a sufficiently strong base to deprotonate non-activated amines in aqueous solution and the hydroxide ion is not readily transferred into the organic phase to facilitate the homogeneous alkylation (see Chapter 1). Additionally, it is known that ion-pairs of quaternary ammonium cations with deprotonated amines are decomposed extremely rapidly by traces of water [4]. However, under solidrliquid two-phase conditions, the addition of a quaternary ammonium salt has been found to increase the rate of alkylation of non-activated amines by a factor of ca. 3-4 [5]. Similarly, the alkylation of aromatic amines is accelerated by the addition of the quaternary ammonium salt the reaction is accelerated even in the absence of an inorganic base, although under such conditions the amine is deactivated by the formation of the hydrohalide salt, and the rate of the reaction gradually decreases. Hence, the addition of even a weak base, such as... 

The authors then go on to measure the kinetics in the presence of two oxazabor-ole catalysts, (92a) and (92b).The rate-determining step is the reaction of the ketone with an oxazaborole-borane complex, with the direct reduction competing with the catalytic cycle (as mentioned above). The oxazaborole reaction, like the direct reduction, is significantly accelerated by the presence of sodium borohydride. 

Recently, the intramolecular nitrile oxide-alkene cycloaddition sequence was used to prepare spiro- w(isoxazolines), which are considered useful as chiral ligands for asymmetric synthesis (321). Reaction of the dibutenyl-dioxime (164) (derived from the diester 163) with sodium hypochlorite afforded a mixture of diastereomeric isoxazolines 165-167 in 74% combined yield (Scheme 6.80) (321). It was discovered that a catalytic amount of the Cu(II) complex 165-Cu(acac)2, where acac = acetylacetonate, significantly accelerated the reaction of diisopropylzinc... 

Effect of sodium and aluminum on TS-1. The catalytic activities of aluminum and/or sodium containing TS-1 are depicted in Table IV. The data show that the addition of aluminum during the synthesis of TS-1 yields a material (TAS-1(D)) that has a lower conversion of n-octane oxidation and a smaller IR peak ratio. The existence of the acid sites due to the incorporation of aluminum into the framework of TS-1 may accelerate the decomposition of H2O2 to water and oxygen during the reaction. However, reducing the number of acid sites by exchanging with sodium ions only increases the conversion by 1% (Na/TAS-1(D)). Therefore, the addition of aluminum into the synthesis mixture most likely reduce the amount of titanium present in the sample. 

A renesulfonylchlorides.1 Sodium arenesulfonates are converted into the sulfonyl chlorides by reaction with POC1, and sulfolane in acetonitrile in 85-95% yields. Yields are poor in the absence of sulfolane. The rate can be accelerated by catalytic amounts of DMF. 

Dicarboxyl starch can also be made by oxidation with sodium hypochlorite or hypobromite (see reference 116). Reaction with hypochlorite is accelerated by use of catalytic amounts of sodium bromide.123,124... 

The analogous reaction of unsaturated lactones and lactams is strongly accelerated in the presence of alcohols which protonate the copper enolate formed in the conjugate reduction.281 This protocol was used in an enantioselective synthesis of the antidepressant (—)-paroxetine 324. Here, the key step was the conjugate reduction of the lactam 322 by PMHS in the presence of /-amylalcohol and catalytic amounts of CuCl2, ( S)- -tol-BINAP, and sodium /-butoxide, giving the product 323 with 90% yield and 90% ee (Scheme 90).281 The second chirality center was installed by diastereoselective alkylation of 323. 

Other metals, the commonest being lead,2 bismuth, and manganese, in powder form exert a more moderate effect on the decomposition. Mercury would also fall into this class of moderate accelerators, but the catalytic action in this case is remarkable in being periodic or rhythmic. When the concentration of hydrogen ion is reduced to an almost negligible quantity by the addition of a little sodium acetate solution, a clean mercury surface in contact with hydrogen peroxide solution of approximately 10 per cent, concentration, at periodic intervals of about one second, becomes coated with a bronze film which suddenly disappears with a burst of oxygen from the contact layer of the two liquids the substance of the film, which is alternately formed and decomposed, is probably an unstable oxide, possibly mercurous peroxide.3... 

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