Trichloroacetic acid chemistry

Most of the chemistry of PA is determined by its acidic nature. It is a strong acid whose ionization constant of 1.6 x 10"1 (Ref 31) makes it comparable in acid strength to pyrophosphoric acid and trichloroacetic acid. PA readily forms salts with bases and esters with alcohols. The salts are known as Picrates. Many of them are expl and will be described in a separate article in this Vol. The esters are phenol ethers, eg, Trinitro-anisolc (see Vol t, A450-L)... 

The decisive contributions made by Plesch to the understanding of the chemistry of cationic polymerisation also includes a pioneering piece of research in this specific area. In 1950, he published a classical paper on the role of trichloroacetic acid as cocatalyst in the polymerisation of isobutene by titanium tetrachloride in hexane at low temperature An analysis of the dependence of the maximum polymerisation rate upon the concentration of monomer was carried out by us frcm the plots published by Plesch and it can be concluded that a second power law was approximately followed. The presence of an excess of TiCl4 over the cocatalyst gave a maximum rate proportional to the concentration of the latter. We assume that in these crmditions the following mechanism accounts for the experimental observations ... 

The reaction of thyinoquinone (74) to yield the y-alkylidene-A -butenolide (79) illustrates the interesting chemistry that 1,4-quinones exhibit upon reaction with sodium azide in trichloroacetic acid . Intermediates 75, 76 and 78 were synthesized and shown to... 

The prevalence of the carboxylate moiety in both biogenic and man-made molecules of interest makes this functional group a popular target for anion host chemistry. Needless to say, carboxylates are a major constituent of proteins, peptides and amino acids, and the expansion of proteomics begets increasing requirements for means of specific detection of such biomolecules. Other relevant examples of carboxylates include fatty acids, while many small molecule di- and tricarboxylates are implicated in key metaboUc pathways such as the citric acid cycle (e.g. citrate, succinate, fumarate and malonate). Carboxylated anthropogenic molecules include trichloroacetic acids, anionic surfactants and S-lactam antibiotics. 

Dumas remained unconvinced until 1838, when he prepared a chlorinated acetic acid (actually trichloroacetic acid) and noted its similarity to acetic acid. He then advanced his own version of Laurent s theory, calling it the theory of types. In organic chemistry there exist certain Types which persist even when in place of hydrogen they contain an equal volume of chlorine, bromine or iodine. Laurent complained bitterly that Dumas had borrowed his ideas without due acknowledgement, and a rift arose between the two men which prevented Laurent s advancement within the French chemical establishment. Dumas proceeded to make... 

Figure 8 Structures of [Eu2L6(H20)4] (HL = / -nitrobenzoic acid) (a) and [Er2Lg(H20)3] (HL = trichloroacetic acid) (b) (RE, black (large balls) N and Cl (black (small balls) O, gray C, white H, omitted). (Reproduced with permission from from R. Wang and Z. Zheng, Rare Earth Complexes with Carboxyhc Acids, PolyaminopolycarboxyUc Acids and Amino Acids in Chun-Hui Huang, Rare Earth Coordination Chemistry Fimdamentals and Applications. John WHey Sons (Asia) Pte Ltd, 2010.)...

Several analogues of Mosher s acid have been developed for determining the stereo-chemistry. In addition, a modified Mosher s method has been used to determined the absolute configuration of some natural products. Moreover, the preparation of MTPA has been improved to one-pot synthesis by the addition of trimethylsilyl trichloroacetate to a,Q, Q -trifluoroacetophenone and subsequent hydrolysis. ... 

Reducing Acids. The corrosion resistance of titaniiun alloys in reducing add media is very sensitive to add concentration, temperature, backgroimd chemistry, and pmity of the add solution, in addition to titanium alloy composition. When the temperatme an or concentration of pure (uncontaminated) reducing add solutions exceed certain values, the protective oxide film of titanium may break down, which would residt in severe general corrosion. Included in this category are hydrochloric, sulfuric, hydrohromic, hydriodic, hydrofluoric, phosphoric, sulfamic, oxalic, and trichloroacetic adds. Because the performance of titanimn alloys in reducing... 

A brief study of the chemistry of the molecules and solutions used in chemical peels immediately questions the hypothesis that acidity is the only basis for the action of peeling solutions. In fact, with the exception of trichloroacetic add (TCA) and non-neutralized glycolic acid solutions, the most commonly used peeling solutions are only weakly acidic, and phenol and resorcinol mixtures may not be acidic at all, having a pH greater than 7 in some formulations. 

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