Carboxylic acids, conjugated compounds

Acyl glucuronides (i.e., ester glucuronides of general structure 11.6) are formed as conjugates of carboxylic acids. These compounds are rather uniquely reactive a) they are far more sensitive to chemical hydrolysis than ether... 

In these papers, the carboxylic acid to be protected was a stable, unsubstituted compound. Harsh conditions were acceptable for both formation and cleavage of the amide. Typically, a simple secondary amide is very difficult to cleave. As the pKa of the conjugate acid of an amide decreases, the rate of hydrolysis of amides derived from these amines increases. The dimethylamide of a cephalosporin was prepared as follows using 2,2 -dipyridyl disulfide. ... 

When primary nitro compounds are treated with sulfuric acid without previous conversion to the conjugate bases, they give carboxylic acids. Hydroxamic acids are intermediates and can be isolated, so that this is also a method for preparing them. Both the Nef reaction and the hydroxamic acid process involve the aci form the difference in products arises from higher acidity, for example, a difference in sulfuric acid concentration from 2 to 15.5 M changes the product from the aldehyde to the hydroxamic acid. The mechanism of the hydroxamic acid reaction is not known with certainty, but if higher acidity is required, it may be that the protonated aci form of the nitro compound is further protonated. 

CHROMIUM TRIOXIDE-PYRIDINE COMPLEX, preparation in situ, 55, 84 Chrysene, 58,15, 16 fzans-Cinnamaldehyde, 57, 85 Cinnamaldehyde dimethylacetal, 57, 84 Cinnamyl alcohol, 56,105 58, 9 2-Cinnamylthio-2-thiazoline, 56, 82 Citric acid, 58,43 Citronellal, 58, 107, 112 Cleavage of methyl ethers with iodotri-methylsilane, 59, 35 Cobalt(II) acetylacetonate, 57, 13 Conjugate addition of aryl aldehydes, 59, 53 Copper (I) bromide, 58, 52, 54, 56 59,123 COPPER CATALYZED ARYLATION OF /3-DlCARBONYL COMPOUNDS, 58, 52 Copper (I) chloride, 57, 34 Copper (II) chloride, 56, 10 Copper(I) iodide, 55, 105, 123, 124 Copper(I) oxide, 59, 206 Copper(ll) oxide, 56, 10 Copper salts of carboxylic acids, 59, 127 Copper(l) thiophenoxide, 55, 123 59, 210 Copper(l) trifluoromethanesulfonate, 59, 202... 

Conjugation of polar groups such as amines, carboxylic acids, and phenolic hydroxyl gronps produce water-soluble compounds that are excreted and these reactions therefore fnnction as a detoxification mechanism. 

Conjugation chemistry for the coupling of haptens to carrier molecules is fairly well defined for compounds having common functional groups to facilitate such attachment. The types of functional groups generally useful for this operation include easily reactive components such as primary amines, carboxylic acids, aldehydes, or sulfhydryls. 

Reduction of a., -unsaturated carbonyl compounds. Hydrosilanes, particularly (QH,)2SiH2, in the presence of Pd(0), and a Lewis acid, particularly ZnCl2, can effect selective conjugate reduction of unsaturated ketones, aldehydes, and carboxylic acid derivatives. Chloroform is the solvent of choice. In addition, 1 equiv. of water is required. Experiments with D,0 and (C6H,),SiD2 indicate that... 

Rule of thumb The stability of molecular ions roughly decreases in the following order aromatic compounds > conjugated alkenes > alkenes > alicyclic compounds > carbonyl compounds > linear alkanes > ethers > esters > amines > carboxylic acids > alcohols > branched alkanes. [81]... 

Diynes have already been used for building polycylic compounds in the presence of CO2 and a stoichiometric amount of Ni(0) bicyclic pyrones were obtained [117]. With the electrocarboxylation method, linear or cyclic mono-carboxylic acids were obtained as main products from non-conjugated diynes depending on the ligand associated to Ni [118, 119]. Thus ring-fomation occurred with the Ni-bipyridine complex at normal pressure of CO2 on the other hand, in the presence of PMDTA as ligand and with a 5 atmosphere pressure of CO2, linear adducts were mainly formed as illustrated in Eq. (16) ... 

---