Products transformation

L. Somasundaram and. R. Coats, eds.. Pesticide Transformation Products Fate and Significance in the Environment, ACS Symposium Series No. 459, American Chemical Society, Washington, D.C., 1991, 308 pp. 

The metaboHsm of a material may result in the formation of a transformation product of lower intrinsic toxicity than the parent molecule ie, a process of detoxification has occurred. In other cases, the end result is a metaboHte, or metaboHtes, of intrinsically greater toxicity than the parent molecule, ie, metaboHc activation has occurred. Some examples of detoxification and metaboHc-activation processes are given in Table 2. 

It is important to appreciate that the magnitude of the absorbed dose, the relative amounts of bio transformation product, and the distribution and elimination of metaboUtes and parent compound seen with a single exposure, may be modified by repeated exposures. For example, repeated exposure may enhance mechanisms responsible for biotransformation of the absorbed material, and thus modify the relative proportions of the metaboUtes and parent molecule, and thus the retention pattern of these materials. Clearly, this could influence the likelihood for target organ toxicity. Additionally, and particularly when there is a slow excretion rate, repeated exposures may increase the possibiUty for progressive loading of tissues and body fluids, and hence the potential for cumulative toxicity. 

The following trivial names have been assigned to the penicillin transformation products shown (6), benzylpenicilloate (7), benzylpenaldic acid (8), D-penicillamine (9), a-methyl D-a-benzylpenicilloate (10), benzylpenillic acid (11), benzylpenillamine (12), benzyl-isopenillic acid (13), benzylpenilloic acid (14), benzylpenilloaldehyde (15), benzylpenicil-lenic acid (16) benzylpenillonic acid methyl ester and (17), dethiobenzylpenicillin methyl ester. 

In the following table the characters of the principal isomerides and other transformation products of the cinchona alkaloids are summarised and references are given to the chief papers dealing with them, and upon which the foregoing account is based. The capital letters in brackets printed after the names of the substances refer to the formulae and explanatory footnote on p. 449. 

Quinine Equia alents of Cinchona Bases and Transformation Products. 

As found in commerce, the cinchona alkaloids are not necessarily pure quinidine, for example, may contain up to 30 per cent, of dihydroquinidine. Working with carefully pmdfied specimens of the four chief cinchona alkaloids and their dihydro-derivatives, Buttle, Henry and Trevan found the results recorded in the table (p. 471) in tests with malaria in canaries. The figures in brackets represent the dose of quinine necessary to produce the same degree of protection as unit dose of the alkaloid named. To the results are also added the data found later by the same authors, with Solomon and Gibbs, for some of the transformation products (p. 449) of quinine and quinidine. The Roman numeral at the head of each column refers to the type formula on p. 470. 

Other investigations of interest are the studies of the isomeric dihydroderivatives of brucine and strychnine and their reactions, carried out by Leuchs and his collaborators, investigation of the red o-quinone (isolated as the perchlorate, CjiHjoO Ng. HCIO4) formed in the well-known test for brucine with nitric acid, and the examination of the transformation products of oximinobrucine by Wieland et al. ... 

Chondrodendron polyanthum, 371 Chondrodendron tomentosum, 363, 371, 373, 377, 391 alkaloids, 376 Chondrodine, 363, 364 Chondrofoline, 364, 365 Chrycentrine, 172, 313 Chiysanthemine, 773 Chrysanthemum cineraricefoHum, 773 Chuchuara, 781 Chuehuhuasha, 781 Cicuta virosa, 13 Cinchamidine, 419, 429 Cinchene, 439 Cinchenine, 438, 439, 440 apoCinchenine, 440, 441 Cincholoipon, 438 Cincholoiponic acid, 438, 443 Cinchomeronic acid, 183 Cinchona alkaloid structure, synthesis, 457 Cinchona alkaloids, bactericidal action of some derivatives, 478 centres of asymmetry, 445 constitution, 435 formulae and characters of transformation products, 449, 451 general formula, 443 hydroxydihydro-bases, 448, 452-4 melting-points and specific rotations, 446... 

The heterocyclic pseudobasic carbinolamines show a very varied reactivity. However, the structure of a large number of their transformation products, in particular those from which conclusions have been drawn as to the structure of the initial pseudo base, are incorrect even in the most recent literature. 

Reaction of 6-methyl-4-oxo-4//-pyrido[l, 2-n]pyrimidine-3-acetic acid (295) with phenylethylamine in boiling xylene afforded ring-transformed product 296 (98ACH515). 

R. G. Lichtenthaler and F. Ranfelt, Determination of antioxidants and their transformation products in polyethylene by high-performance liquid chromatography , J. Chromatogr. 149 553-560 (1978). 

Transformation products of stabilizers formed during melt processing may exert either or both anti- and/ or pro-oxidant effects. For example, in the case of BHT, peroxydienones, PxD (reactions 9b, b") lead to pro-oxidant effects, due to the presence of the labile peroxide bonds, whereas quinonoid oxidation products, BQ, SQ, and G- (reaction 9 b, c, d) are antioxidants and are more effective than BHT as melt stabilizers for PP [29], The quinones are effective CB—A antioxidants and those which are stable in their oxidized and reduced forms (e.g., galvinoxyl, G-, and its reduced form, hydrogalvi-noxyl, HG) may deactivate both alkyl (CB—A mecha-... 

Scheme 9 Oxidative transformation products formed during the antioxidant action of BHT.

Parker, The Transformation Products of Carbamite Produced in the Ageing of Service Propellants , GtBrit AML Rept A/12(M) March 1948 8) B.L. Hollingsworth, JCS 1959, 2420... 

Organophosphate flame retardants and plasticisers Perfluorinated compounds Pharmaceuticals and personal care products Polar pesticides and their degradation/transformation products Surfactants and their metabolites... 

A reported method for the screening for transformation products of a number of pesticides [16] provides an elegant example of the complementary nature of the product-ion, precursor-ion and constant-neutral-loss scans (see Section 3.4.2 above). 

The product-ion spectra of the (M - - H)+ ions of atrazine, the structure of which is shown in Figure 3.29, and three of its transformation products showed that if the isopropyl side-chain was present in the structure a constaut neutral... 

Figure 3.29 Structure of atrazine. Reprinted from J. Chromatogr., A, 915, Steen, R. J. C. A., Bobeldijk, I. and Brinkman, U. A. Th., Screening for transformation products of pesticides using tandem mass spectrometric scan modes , 129-137, Copyright (2001), with permission from Elsevier Science.

Very little information exists in the literature on the transformation and degradation of methyl parathion in air. An early study indicated that direct photolysis of methyl parathion may occur however, the products of this photolysis were not determined (Baker and Applegate 1974). A later study found a transformation product of methyl parathion, methyl paraoxon, in air samples taken from areas where methyl parathion had been applied. Formation of methyl paraoxon was attributed to the vapor phase oxidation of methyl parathion (Seiber et al. 1989). Recent monitoring studies in California have also found both methyl parathion and methyl paraoxon (Baker et al. 1996). 

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