Replacement of carboxyl

Replacement of Carboxylic Acid, Acetal, and Alkoxy Groups (Especially of Functional Groups of Sugars)... 

This synthetic method is applied for obtaining aromatic [11] and heteroaromatic [5,292] Ji-complexes. Thus, the replacement of carboxyl groups leads to the following ri6-jr-Ar-metal carbonyl complexes ... 

The Hunsdiecker method has been applied effectively for the replacement of carboxyl by bromine and iodine [39 2] (Figure 8.3) but on an industrial scale the products are more effectively obtained by other processes [43]. Routes starting from aUcenes are particularly significant (Figure 8.4). It is important to note that the toxicities of these iodoaUcanes appear to be increased dramatically from that of trifluoroiodomethane, which is relatively harmless (and has unwisely been considered as a fire-extinguishing agent), to those of the tertiary iodides, which are dangerously toxic [44]. 

Rednction of the specific amonnt of expensive foreign equipment, particularly the replacement of carboxylic heat exchangers for Rnssian graphite ones. 

Figure 3.12 Further examples of heterocyclic ring replacements of carboxylic acid groups the 5-oxo-l,2,4-oxadiazole 18 and 5-oxo-l,2,4-thiadiazole derivative 19.

Phosphonylation of a Carboxylic Acid Polymer. The reaction of a water-soluble polycarboxylic acid with phosphorous acid is said to yield a polymer with hydroxybis(phosphonic acid) structures. These are effective scale-inhibiting agents for aqueous systems (119) but not known to have been commercialized. A similar reaction in a Chinese study is said to result in the replacement of carboxyl groups by phosphonic acid groups (120) to produce pol5uners with similar utility. 

Replacement of carboxyl by alkoxy groups Mixed acetals from a-alkoxycarboxylic acids... 

Reactions in which hydroxypyridines are formed by replacement of acyl or carboxyl groups are imknown or rare. Examples of replacement of carboxyl during the Decker reaction have been mentioned, as has the conversion of 2-carboxy-5-methoxycarbonylpyridine 1-oxide into 6-hydroxynicotinic acid by benzoyl chloride in dioxan. The latter reaction has been represented as... 

Replacement of carboxyl groups via hydroxy-decarboxylation, although formally involving the oxidative cleavage of a carbon-carbon bond (Section 10.2.4), is discussed here because of... 

Replacement of carboxyl by methyl Kolbe electrolysis with acetic acid... 

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