Oxygen-substituted acid

Bivalent Sulfur. The prefix thio, placed before an affix that denotes the oxygen-containing group or an oxygen atom, implies the replacement of that oxygen by sulfur. Thus the suffix -thiol denotes — SH, -thione denotes —(C)=S and implies the presence of an =S at a nonterminal carbon atom, -thioic acid denotes [(C)=S]OH [(C)=0]SH (that is, the O-substituted acid and the 5-substi-... 

Hydroxyall l Hydroperoxyall l Peroxides. There is evidence that hydroxyalkyl hydroperoxyalkyl peroxides (2, X = OH, Y = OOH) exist in equihbrium with their corresponding carbonyl compounds and other a-oxygen-substituted peroxides. For example, reaction with acyl haUdes yields diperoxyesters. Dilute acid hydrolysis yields the corresponding ketone (44). Reduction with phosphines yields di(hydroxyalkyl) peroxides and dehydration results in formation of cycHc diperoxides (4). 

In a synthesis of gibberellic acid, a diene and quinone, both with oxygen-substituted side chains, gave the initial intermediate. Later in the synthesis, an intramolecular D-A reaction was used to construct the A-ring. 

Firedamp-proof Detonators. Firedamp-proof detonators have net received tht attention that firedamp-proof expls have, possibly because the expln of the, detonator is lost in the immediately succeeding expln of the main charge. Treatment of the detonator charge in caps follows similar lines to treatment of Dynamites in the addition of cooling additives, such as salts or wax (Ref 1), BuOAc (butyl acetate) (Ref 2), or poly car boxy lie acids, oxygenated poly carboxylic acids, halogen substituted poly carboxylic and oxygenated polycarboxylic acids, and the neutral and acid salts of these (Ref 4)... 

Substituted cobalt porphyrins as catalysts in sulfuric acid. Further very active chelates for the reduction of oxygen in acids discovered in the early 70s were CoTPP by Sandstede and co-workers 9,13-15) and CoTAA and FeACC by Beck and co-workers 8 12>. Sandstede et al. determined the activities of their chelate catalysts by the suspension method briefly explained in Section 2.2.2.3. 

The most common procedure is ozonolysis at -78 °C (P.S. Bailey, 1978) in methanol or methylene chloride in the presence of dimethyl sulfide or pyridine, which reduce the intermediate ozonides to aldehydes. Unsubstituted cydohexene derivatives give 1,6-dialdehydes, enol ethers or esters yield carboxylic acid derivatives. Oxygen-substituted C—C bonds in cyclohexene derivatives, which may also be obtained by Birch reduction of alkoxyarenes (see p. 103f.), are often more rapidly oxidized than non-substituted bonds (E.J. Corey, 1968 D G. Stork, 1968 A,B). Catechol derivatives may also be directly cleaved to afford conjugated hexa-dienedioic acid derivatives (R.B. Woodward, 1963). Highly regioselective cleavage of the more electron-rich double bond is achieved in the ozonization of dienes (W. KnOll, 1975). 

This concludes the discussion of the stabilities of carbocations with hydrocarbon-based structures and also of different methods for deriving equilibrium constants to express these stabilities. The remainder of the chapter will be concerned mainly with measurements of stabilities for oxygen-substituted and metal ion-coordinated carbocations. Consideration of carbocations as conjugate acids of carbenes and derivations of stabilities based on equilibria for the ionization of alkyl halides and azides will conclude the major part of the chapter and introduce a discussion of recent studies of reactivities. 

The lower reactivity of the o-thioquinone methide 81 (7.0 x 104 M-1 s 1) compared with the o-l (8.4 x 105 M-1 s 1) in acidic solution contrasts with the much higher reactivity of 81 at neutral pH (Table 1). This may represent the balance between the smaller concentration of the protonated thioquinone methide compared with protoned o-l due to the weaker basicity of o-S (pATa < —3 Table 1) compared with o-S (pKa < —1.7) and the presumably greater intrinsic reactivity of H-81 +. 58 However, the observed effects of sulfur for oxygen substitution on carbocation reactivity have in the past proven very difficult to rationize,130,160 and in the present case are probably not fully understood. 

The first examples of a direct substitution upon the carbon atoms of the dioxetane core have now appeared (Scheme 9) <1997JA245>. Thus, treatment of alkylthiodioxetane 49 with a slight excess of a Lewis acid oxidant such as iV-chlorosuccinimide (NCS) or mercuric acetate in the presence of excess ROH leads to the formation of oxygen-substituted dioxetanes 50 in low to moderate yields. 

For example, picric acid is a strong gas phase acid aliphatic alcohols are weak gas phase acids. Oxygen substitution reactions leading to phenolate ions occur for some substances. 

Scheme 52 and Table 6 emphasize the beneficial influence of high pressure on the Diels-Alder reactions of (Lewis acid sensitive) nitrogen- or oxygen-substituted dienes (221) to acrylates (222) cf. entries 1/2 and 3/4). ... 

Oxygen-substituted compounds — peroxomonophosphate The hydrolysis of peroxomonophosphoric acid (H3PO5), viz. 

Uncertainties in identifying specific functional groups results in a range of n. The lower limit considers all aromatic carbon to be nonprotonated, the oxygen-substituted carbon to be a tertiary ether, the caiboxylate to be an ester, and the carbonyl to be a ketone. The upper limit is derived by assuming that all the aromatic carbon is protonated, the oxygen-substituted carbon is a primary alcohol, and the carboxylate is an acid. 

The maximum value of m is derived by assuming that all oxygen-substituted alkyl carbon is in the form of alcohol, all the oxygen-substituted aromatic carbon is hydroxyl, and the carboxylate is in the form of free acid. The minimum value of m is derived by assuming that all carboxylate is linked to aromatic carbon via aromatic esters, the remainder of aromatic oxygen is linked to aliphatic carbon via alkyl aryl ethers, and that the remainder of the aliphatic oxygen linked as aliphatic ethers. 

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