Hydroxide , generation

Electrochemical Process. Applying an electrical current to a brine solution containing propylene results in oxidation of propylene to propylene oxide. The chemistry is essentially the same as for the halohydrin process. AH of the chemistry takes place in one reactor. Most of the reported work uses sodium or potassium bromide as the electrolyte. Bromine, generated from bromide ions at the anode, reacts with propylene and water to form propylene bromohydrin. Hydroxide generated at the cathode then reacts with the bromohydrin to yield propylene oxide (217—219). The net reaction involves transfer of two electrons ... 

Outer crust. A friable outer crust forms atop the tubercle. The crust is composed of ferric hydroxide (hematite), carbonates, silicates, other precipitates, settled particulate, and detritus. Ferrous ion and ferrous hydroxide generated within the tubercle diffuse outward through fis-... 

Treatment of 1-pyridinium sulphonate with sodium or potassium hydroxide generates sodium or potassium salts of 5-hydroxy-2,4-pentadienal (glutaconaldehyde), which are starting materials for a variety of transformations (equation 178)171b 301. For example, the reaction of the potassium salt with a carbon electrophile has been used for the preparation of a dienol aldehyde (equation 179)mb which was an intermediate in the total synthesis of a mutagen, (S)-3-(dodeca-l,3,5,7,9-pentaenyloxy)propane-l,2-diol. 

In another procedure, oxidation is carried out in the presence of chloride ions and ruthenium dioxide [31]. Chlorine is generated at the anode and this oxidises ruthenium to the tetroxide level. The reaction medium is aqueous sodium chloride with an inert solvent for the alkanol. Ruthenium tetroxide dissolves in the organic layer and effects oxidation of the alkanol. An undivided cell is used so that the chlorine generated at the anode reacts with hydroxide generated at the cathode to form hypochlorite. Thus this electrochemical process is equivalent to the oxidation of alkanols by ruthenium dioxide and a stoichiometric amount of sodium hypochlorite. Secondary alcohols are oxidised to ketones in excellent yields. 1,4- and 1,5-Diols with at least one primary alcohol function, are oxidised to lactones while... 

In the reaction, one mole of hydroxide generates one mole of alcohol and one mole of carboxylate ion from one mole of ester. Based on this stoichiometry (the mole relationship as defined by the balanced chemical equation), if the number of moles of base is known, then the amount of ester is known. 

Procedure Into a suitable beaker, flask, ect., place 250 milliliters (8.5 fluid oz.) of cold water, and then add and dissolve 51 grams (1.8 oz.) of sodium hydroxide. Note sodium hydroxide generates excessive heat when dissolved in water so use caution. Thereafter, add in, in small portions at a time, 50 grams (1.7 oz.) of powdered sulfur, and stir the mixture vigorously during the addition. Note more sulfur may be added if desired. Thereafter, continue to stir the mixture for about 30 minutes. After 30 minutes the mixture is ready for use. Even though the mixture will be contaminated with sodium thiosulfate, it can be used directly in the reduction of nitro compounds. 

Reaction of diphenyl diselenide or dimethyl diselenide with hydrazine hydrate and sodium hydroxide generates the corresponding selenolates smoothly in solvents like DMF or diethyl ether and in the presence of tetrabutylammonium chloride as a phase-transfer catalyst [13]. The selenolates react with organic halides to give various selenides (Scheme 9). Similar conditions have been applied to the synthesis of aryl vinyl selenides from diaryl diselenides and acetylene [14]. 

Bazinet L, Montpetit D, Ippersiel D, Mahdavi B, Amiot J, and Lamarche F. Neutralization of hydroxide generated during skim milk electroacidification and its effect on bipolar and cationic membrane integrity. J. Membr. Sci. 2003 26(1-2) 229-239. 

Cellulose can be dissolved in cuprammonium hydroxide, generating cuproxam lignin. ... 

S. Mazrou, H. Kerdjoudj, A.T. Cherif, A. Elmidaoni and J. Molenat, Sodium hydroxide and hydrochloric acid generation from sodium chloride and rock salt by electro-electrodialysis, J. Appl. Electrochem., 1997, 27, 558-567 A.T. Cherif, J. Molenat and A. Elmidaoni, Nitric acid and sodium hydroxide generation by electrodialysis using bipolar membranes, J. Appl. Electrochem., 1997, 27, 1069-1074. 

When the sulfone has an a-halo substituent, formation of the carbanion is often accompanied by loss of the SO2 moiety via the so-called Ramberg-Backlund reaction.335 An illustration is the conversion of 1-bromo-ethyl ethyl sulfone (327) to 2-butene.336 Initial reaction with potassium hydroxide generated the sulfone carbanion (328), which displaced bromide intramolecularly to give an episulfone (329). Under the reaction conditions, 329 lost sulfur dioxide (SO2) to give the alkene. Meyers introduced a modification of this reaction in which the sulfone was converted directly to the alkene without isolating the a-halosulfone, using KOH in CCl4.337,338 Sulfuryl chloride and bromine can also be used.338... 

Oxytelluration of olefins with PhTeBrs or Ph2Te2-Br2 in aqueous THF generates (P-hydroxyalkyl)aryltelluiium dihalides. The reaction is tran -stereospecific in the case of cw-2-butene and cis- and trans-4-octenes and regiospecific in the cases of all terminal olefins. Their reactions with reducing agents in aqueous sodium hydroxide generate the Markovnikov hydration products. 

Sodium hydroxide reacts with trichloroethylene, forming explosive mixtures of dichloroacetylene. When heated with phosphorus pentoxide, a violent explosion can result (Mellor 1946, Suppl. 1971). Phosphorus boiled with caustic soda solution can produce phosphine, which ignites spontaneously in air. Amphoteric metals such as aluminum, zinc, and tin react with sodium hydroxide, generating hydrogen, which may form explosive mixtures in air. 

A modified interfacial mechanism has been proposed by Starks [1] assuming that tetraalkylammonium hydroxide, generated at the interphase by ion exchange between ammonium halide and sodium hydroxide, acts as a base for substrate deprotonation. This mechanism has been disputed by Mqkosza through competitive addition of CCl3 anions to A-alkylpyridinium salts and carbanion acceptors such as vinyl acetate [31]. 

Volatility of different alkali metal hydroxides generated in the moist cathode atmosphere... 

Deprotection. Deprotection of 2-(trimethylsilyl)ethyl esters using sodium hydride in DMF occurred cleanly in the presence of other sUyl ethers (eq 59). The reactive intermediate is presumed to be traces of anhydrous sodium hydroxide generated from adventitious water in the solvent. 

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