Derivatization, aims

Dehydrocorticosterone 221 Demeton-S-methyl 362 Demeton-S-methylsulfone 362 Deoxynivalenol 89,147,148 Derivatization, aims 56, 57 -, during development 57 -, for clean up 56 -, in situ 56... 

Drug residues that do not sufficiently absorb or fluoresce are usually submitted, prior to their analysis by physicochemical techniques, to some type of derivatization aimed primarily at enhancing analyte detectability. Furthermore, formation of relatively nonpolar derivatives offers advantages for a successful extraction and cleanup. 

In the frame of a medicinal project at J J Pharmaceutical Research and Development aimed at designing new potent and selective glycogen synthase kinase-3/i (GSK-3/3) inhibitors, the C-3 derivatization of the 1-methyl-4-[l-alkyl-lff-indol-3-yl]-lff-pyrrole-2,5-dione scaffold was explored [31]. Microwave-assisted Stille reaction of 3-chloro-l-methyl-4-[l-alkyl-lff-indol-3-yl]-lH-pyrrole-2,5-diones with (2,4-dimethoxy-5-pyrimidinyl)(tributyl) stannane at 200 °C yielded in 6 min the desired 3,4-diaryl-lff-pyrrole-2,5-diones in moderate yields (Scheme 12). 

In the above-mentioned method by Hodgeson el acifluorfen was determined by GC/ECD after the extraction with a 47-mm PS-DVB disk and derivatization with diazomethane. The conditions for GC/ECD were as follows column, DB-5 fused silica (30 m X 0.32-mm i.d., 0.25-p.m film thickness) He carrier gas velocity, 25 cm s (210°C), detector makeup gas, methane-argon (5 95), 30mLmin column temperature, 50 °C (5 min), 10°Cmin to 210 °C (5 min) and to 230 °C (10 min) injection port and detector temperature, 220 and 300 °C, respectively injection method, splitless mode. The recovery of acifluorfen from purified water, dechlorinated tap water and high humic content surface water fortified at 0.5-2.0 ug was 59-150% and the LOD was 25 ngL Acifluorfen after derivatization with various chlorofor-mates was also determined by GC/MS using an SE-54 column (25 m x 0.20-mm i.d., 0.32- um Aim thickness), and the average recovery of acifluorfen fortified between 0.05 and 0.2 ugL was 78%. ... 

The traditional way of producing derivatives for analytical purposes aims at preserving, as much as possible, the important structural features of the analyte. In the case of organotin compounds this means that the tin moieties of the compound should appear in the derivative, as occurs in the methods described in Section V.A. Nevertheless, many organotin compounds are important intermediates in the synthesis of organic compounds devoid of metallic atoms. Such procedures can afford good derivatizing schemes, as described in Section V.B. 

There are two basic aims of chemical derivatization simplification of the fragmentation pattern by either promoting or demoting formation of a chosen ion series, and stable-isotopic labelling for simple assignment of ions to proper ion series (Fig. 6.21). Both methods may provide good results and their advantages and limitations will be discussed. 

These and several other researchers extended the methodology with the aim to widen functionality, using dopant molecules and silicon precursors derivatized with organic moities giving place to a vast class of hybrid organic-inorganic organosilica nanocomposites capable to meet numerous, advanced requirements in fields as diverse as catalysis,... 

Surface modification can be achieved by the surface derivatization of functional-group-bearing low-molecular-weight substances, the grafting of polymer to and from the surface and amphiphilic polymer coating. The main theme of this article is focused on initiator-transfer-terminator (iniferter)-based grafting-from-surface and derivatization-on-surface approaches aiming at precision surface architectures, which are primary determinants of the biocompatibility of medical devices. 

It is not our aim to produce another general book on liquid chromatography. The chapter on background is therefore rather brief and it touches on many areas which are not necessarily directly related to separation techniques but which are relevant to derivatization. This chapter should enable the practical worker to recollect some of the fundamental principles involved. The third chapter is concerned with instrumentation. 

Here we illustrate selected examples of common derivatization reactions on heterocycles grafted on the solid phase. The aim is to provide a sense of the relevant factors and experimental conditions that allow application of known chemical reactions on solid supported heterocyclic substrates for the preparation of novel compounds. In industry, it is not uncommon to seek and secure novelty in a whole chemical class rather than in single derivatives. A direct route to broad coverage aims at the development of a novel heterocyclic scaffold, which in turn is derivatized with standard reactions in order to create a thematic library. The novel scaffold material may be prepared in bulk, typically in solution. Subsequently it is loaded onto a solid support, which is then appropriately portioned for multiple derivatizations in parallel. The latter may involve common reactions, but the resulting products are novel. 

As of today, the variety of chemical reactions already applied in the solid-phase synthesis format is very rich and comprises the majority of the organic synthesis reactions with significant preparative scope. However, the number of examples describing the use of classic reactions for the decoration of solid supported scaffolds, i.e., aiming at standardized derivatization of already formed heterocycles, is still surprisingly low. The reaction types previously mentioned in this chapter seem to be the most frequently applied for this specific purpose. In this section we cover... 

The hydroxyl groups encircling the bucket rims also offer sites for the attachment of a reporter site. Most synthetic methodologies for site derivatization have been developed in studies aimed at promoting biomimetic transformations of substrates included within the CD cavity [144-146], Notwithstanding, these... 

The final section addresses degradation and oxidation reactions in a commonly used derivatization system for cellulose, a mixture of DMSO and phenyl isocyanate to achieve cellulose carbanilation, e.g. for analytical purposes. Mechanistic studies were aimed at verifying the assumed oxidative action of this reaction system, and trapping methodology was employed to detect responsible intermediates. 

Copper(II) polyamine complexes are substitutionally labile, in a manner similar to the corresponding nickel(II) complexes. This means that individual donor atoms may at times decoordinate and thus be available for derivatization reactions, e.g., with suitable carbonyl compounds. More complex ligands may thus be constructed, including macrocycles (35), polymacrocycles (36 38), and concave chelators (35). The copper(II) complex of 1 was synthesized as a starting material for reactions aiming at the derivatization of the pentaamine ligand (24-28). 

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