Hydroxide oxygen bases

In the early studies on luminol and related hydrazides the systems used were composed of either sodium or potassium hydroxide, as base, hydrogen peroxide as the oxidizing agent (more recently molecular oxygen, hypochlorite, iodide, and permanganate have also been used), and some type of initiator or activator. This initiator was frequently hypochlorite, persulfate, a transition metal... 

More recently (49) the reactions of iron carbonyls with alkali hydroxides and with nitrogen and oxygen bases have been once again thoroughly examined, so that the absorption spectra in the visible region of [Fe(CO)4]2, [Fe2(CO)8]2, [Fe3(CO)i, ]2 , [I e4(CO) 3]2, and of the corresponding hydrogen anions have been studied. 

Negatively charged oxygen bases "OH (hydroxide) and its organic derivatives... 

The oxygen bases, alkali metal carbonates, alkali metal hydroxides and alkoxides are used to a large extent. The solvents are alcohols, ether, THF, dioxane, glycol or glycol ethers (for higher temperatures), DMSO, HMPA or crown ethers. The latter three increase basicity by generating naked anions, because the cations are strongly solvated. 

Some of the specific numbers in Table V are more difficult to understand, however. Peroxide, although an oxygen base like hydroxide, shows preference for bonding to carbon. Hydrazine and methoxylamine anions give the same value of KRXHX with the aldehyde but significantly different values with the triarylmethyl system. No explanations are apparent. 

The relative selectivity for nucleophilic reaction at one of the three amide bonds in 176 has been examined by Bruice and co-workers.146,147 Primary and secondary amines generally yield the deacylated compound 177 while oxygen bases (e.g., formate, acetate, hydroxide ion) provide the ring-cleaved product 178 Eq. (63)1. 

Of the various methods of preparing phosphorus ylides, that much preferred — apart from a few exceptions — is the action of bases on phosphonium salts. The strength of the base is adjusted to the acidity of the phosphonium salt bases used have been carbon bases such as butyl- and phenyllithium, nitrogen bases such as sodamide, lithium diethylamide, and 1,5-diazabicyclo-[4.3.0]non-5-ene, and oxygen bases such as sodium hydroxide and potassium alkoxides. The pairs dimethylsulfoxide-sodium hydride1000 and dimethyl sulfoxide-potassium terf-butoxide1001 have proved particularly valuable. 

The chemiluminescence quantum efficiency of luminol is practically the same in anhydrous DMS0/base/02 and in the aqueous alkaline H202/hemin system [33]. Addition of small amounts of water to the DMSO system drastically diminishes, the chemiluminescence light intensity. In a mixed solvent of DMSO/28 mole water/potassium hydroxide/oxygen the relative intensity was only 1/30,000 of that in the DMSO/t-butoxide/02 system [43a]. 

Recall that the carbon atom of carbon dioxide bears a partial positive charge because of the electron attracting power of its attached oxygens When hydroxide ion (the Lewis base) bonds to this positively polarized carbon a pair of electrons in the carbon-oxygen double bond leaves carbon to become an unshared pair of oxygen... 

The proton transfer equilibrium that interconverts a carbonyl compound and its enol can be catalyzed by bases as well as by acids Figure 18 3 illustrates the roles of hydroxide ion and water m a base catalyzed enolization As m acid catalyzed enolization protons are transferred sequentially rather than m a single step First (step 1) the base abstracts a proton from the a carbon atom to yield an anion This anion is a resonance stabilized species Its negative charge is shared by the a carbon atom and the carbonyl oxygen... 

Manganese Hydroxide. Manganese hydroxide [18933-05-6] is a weaMy amphoteric base having low solubihty in water. Mn(OH)2 crystals are reported to be almost pure white and darken on exposure to air. Manganese dihydroxide occurs in nature as the mineral pyrochroite and can also be prepared synthetically by reaction of manganese chloride and potassium hydroxide that is scmpulously free of oxygen. The entire reaction is conducted under reducing conditions (36). 

Hydrolysis is accelerated in the presence of strong acids. However, in the presence of aqueous bases such as sodium hydroxide, the rate of decomposition increases with increasing pH and teaches a maximum at the of the petoxycatboxyhc acid (ca 8.25), then decreases at higher pH (169,170). The basic decomposition products include the parent catboxyhc acid and singlet oxygen (171,172). Because the maximum rate of decomposition occurs at the p-K, the petoxycatboxyhc acid and its anion ate involved in the transition state (169). 

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