Carboxylic acid oxidation

H02C(CH2) C02H it was found that beyond a certain point the increment in the rate coefficient for an increases of one in n is constant at 5.2 x 10 l.mole . sec which compares with a value of 5.73 x 10 1.mole . sec for n-paraffin oxidation (p. 293). It is clear that carboxylic acids behave as paraffins except that a slight retardation due to the inductive effect of -CO2H is apparent. Permanganate behaves in much the same way and some examples of carboxylic acid oxidation have been cited in the section on hydrocarbons. 

The cyano group is at the carboxylic acid oxidation level, so nitriles are potential precursors of primary amides. Partial hydrolysis is sometimes possible.146... 

CH3 oxidation to alcohol and carboxylic acid oxidation and subsequent opening of the pyrrolidine ring 3-hydroxylation of the pyridine ring... 

Effective conditions for oxidation of aldehydes to carboxylic acids with KMn04 involve use of t-butanol and an aqueous NaH2PC>4 buffer as the reaction medium.173 Buffered sodium chlorite is also a convenient oxidant.174 175 An older reagent for carrying out the aldehyde — carboxylic acid oxidation is silver oxide. 

For other examples of alcohol to carboxylic acid oxidations in Ch. 1 cf. 2.3.6. 

Several other processes have been developed, however, to accomplish the oxidative decarboxylation of carboxylic acids oxidation by Pb(OAc)4, by iodosobenzene-diacetate, and by Ag(II) salt generated in situ in a catalytic cycle from a variety of peroxides (benzoyl peroxide, percarbonate, perborate) [2] other than the already mentioned peroxydisulfate. Representative examples are shown in Eqs (9)—(12) of Table 2. 

Although the aforementioned routes provided the desired y-amino acids, it was desirable to develop a synthesis which incorporates the carboxylic acid oxidation state prior to coupling. We hypothesized that manganese-mediated radical addition would accomplish this objective, and therefore initiated a study of manganese-mediated coupling of alkyl iodides with y-hydrazonoesters [104]. We had already shown that the manganese-mediated radical addition conditions offer excellent chemoselectivity, but it remained to be seen whether the stereocontrol model would be disrupted would an additional Lewis basic ester function in the hydra-zone interfere with the role of In(III) in two-point binding and rotamer control ... 

The tetrathioorthocarbonate 186 undergoes a similar reaction to produce a useful one carbon nucleophile at the carboxylic acid oxidation level,149 and substitution on the cyclopropananone thioacetal 188 provides an alternative way of making Trost s150 lithiated sulfide 189.151... 

This is a good way of reducing compounds at the carboxylic acid oxidation level to aldehydes, which is why we included it in the table of carbonyl reductions on p. 622. The tertiary amine is needed both to neutralize the HCl produced in the reaction and to moderate the activity of the catalyst (and prevent over reduction). You will notice too that the catalyst support is different Pd/BaS04 rather than Pd/C. BaS04 (and CaCOs) are commonly used as supports with more easily reduced substrates because they allow the products to escape from the catalyst more rapidly and prevent overreduction. Acyl chlorides are among the easiest of all compounds to hydrogenate—look at this example. 

A number of thiocaibonyl compounds in the carboxylic acid oxidation state have been utilized in Diels-Alder reactions, but no systematic study in this area has been done. Some of the various structural types of thiocarbonyls which are reactive dienophiles are indicated in equations (90), (91) and (92).16s Reactions of this class show good to moderate regioselectivity, but relatively little is loiown with regard to stereoselectivity. Additional examples can be found in earlier reviews. ... 

In DMF solution, however, PDC oxidizes nonconjugated primary alcohols to the corresponding carboxylic acids.Oxidations of 2° alcohols by PDC in DMF proceed to give the corresponding ketones. 

For both the alcohol and the carboxylic acid oxidation levels, the best organometallic reagent is probably the very simple protected lithium derivative 84 introduced by Eaton.24 Easily made from available bromopropanol 82, the acetal 83 gives the stable (because of chelation by one or both acetal oxygen atoms ) lithium derivative 84 by oxidative insertion. 

Upon interaction of the Jt-basic metal fragment (W(Tp)(NO)(L/) with L (L = Melm or PMe3 L = benzene, acetaldehyde, acetone, ethyl acetate, methyl formate, and N,N-dimethylformamide) stable [W(Tp)(NO)(PMe3)(r]2-L)] complexes formed. When the tungsten fragment is combined with a carboxylic acid, oxidative addition yields the seven-coordinate hydride complex [W(Tp)(NO)(H)(PMe3)C(=0)R] (Fig. 2.43).108... 

Aminoimidazole-4-carboxamides (or -nitriles) interact with components at the carboxylic acid oxidation level giving purines, the carboxyl carbon becoming C-2. 

The rate of carboxylic acid oxidation should be proportional to the rate of sulfite oxidation and the acid concentration ... 

McMurry, Diels-Alder, Scholl, and Wittig reactions as well as zn fra molecular cyclodehydration procedures of carboxylic acids, oxidation of hydrogenated aromatics and reduction of quinones and phenols have already been extensively reviewed [26,30] and will be mentioned only in few exemplified syntheses of new parent aromatic systems or in those cases when significant modifications result in much improved yields and/or milder reaction conditions. 

Esterification (formation of an ester) with carboxylic acids oxidation to aldehydes, ketones, and carboxylic acids... 

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