Reactive substances grouping

Suong oxidizers have more potential incompatibilities than perhaps any other chemical group (with the exception of water reactive substances). It is safe to assume that they should not be stored or mixed with any other material except under carefully controlled conditions. Common oxidizing agents listed in decreasing order of oxidizing strength include ... 

In liquid chromatography, in contrast to gas chromatography [see Section 9.2(2)], derivatives are almost invariably prepared to enhance the response of a particular detector to the substance of analytical interest. For example, with compounds lacking an ultraviolet chromophore in the 254 nm region but having a reactive functional group, derivatisation provides a means of introducing into the molecule a chromophore suitable for its detection. Derivative preparation can be carried out either prior to the separation (pre-column derivatisation) or afterwards (post-column derivatisation). The most commonly used techniques are pre-column off-line and post-column on-line derivatisation. 

Primary amines and substances with reactive methylene groups react with 1,2-naphthoquinone-4-sulfonate to yield intensely colored p-quinoid derivatives, which, in the case of aryl amines, are indophenol dyes [12, 13]. 

Hassoun et al. (1993) examined the effects of various pesticides on lipid peroxidation and DNA single strand breakage in the hepatic cells of female Sprague-Dawley rats. Animals were dosed orally once with endrin at 4.5 mg/kg, lindane at 30 mg/kg, chlordane at 120 mg/kg, or DDT (dichlorodiphenyl trichloro-ethane) at 40 mg/kg, or vehicle only (com oil, control). At 6, 12, and 24 hours post-dosing, 4 animals from each group were sacrificed, their livers removed, and prepared for lipid peroxidation assay. Lipid peroxidation was measured calorimetrically by determining the amount of thiobarbituric acid reactive substances (TBARS) formed. Exposure to endrin resulted in a 14.5% increase in hepatic mitochondrial... 

Chemical instability of medicinal agents may take many forms, because the drugs in use today are of such diverse chemical constitution. Chemically, drug substances are alcohols, phenols, aldehydes, ketones, esters, ethers, acids, salts, alkaloids, glycosides, and others, each with reactive chemical groups having different stability characteristics. Chemically, the most frequently encountered destructive processes involve hydrolysis and oxidation. 

The Mannich reaction is a particularly good method of introducing a reactive functional group into a sensitive aromatic nucleus. The reaction has been very useful in ferrocene chemistry. Treatment of chromium acetylacetonate under Mannich conditions yielded a tris-V,N-dimethylaminomethyl chelate (XXXIII). This remarkable substance was very difficult to purify because of its extreme solubility in all solvents ranging from n-heptane to water. The trisamino chelate (XXXIII) is a deep purple, hydroscopic oil and behaves like a typical organic amine. Reaction of this amine with methyl iodide afforded a trisquater-nary ammonium salt (XXXIV), soluble in water but insoluble in organic solvents. When this salt (XXXIV) was treated with cyanide ion, trimethylamine was lost and the cyanomethyl chelate (XXXV) was formed. 

Cyclization of the free acids in acetic anhydride may lead to the decarboxylated 3-acetoxy derivative (Section 3.15.2.2.3). Several 3-hydroxybenzo[6]thiophenes were obtained in excellent yield by the interaction of phenylsulfonylbenzisothiazolone with substances containing a reactive methylene group in the presence of pyridine (equation... 

The chemical structure of the epoxy matrix constituent as well as processing are reported to strongly influence 11 -I3> the thermoset network and hence the properties and durability of the crosslinked polymer 11 ,4-16). The cure of a reactive prepolymer involves the transformation of low-molecular-weight reactive substances from liquid to rubber and solid states as a result of the formation of a polymeric network by chemical reaction of some groups in the system. Gelation and vitrification are the two macroscopic phenomena encountered during this process which strongly alter the viscoelastic behavior of the material. 

The number of 1,2,4,5-tetrazines used in these cycloaddition reactions is limited. The most frequently used are the 3,6-dicarboxylates, the 3,6-diphenyl, 3,6-dimethyl, 3,6-di(2-pyridyl) and bis(perfluoroalkyl) compounds a few others have also been used. The most reactive substances seem to be the 1,2,4,5-tetrazinedicarboxylates, possessing the extra electron-withdrawing effect of the two carboxylate groups. 

The cyclopropane hydrocarbons which nawe three substituent groups are all reactive substances. The 1,1,2 a fcl 1,2,3 trimethyl compounds have been discussed. Besides tnese,two 1,1,2 compounds are xnown wnich have been prepared by tne same method as was uBed for maxing phenylcycxopropane,tnat is,from an... 

Main-group metal alkyls and aryls are valuable tools in preparative organic and inorganic chemistry, and many industrial applications are known for these reactive substances. In addition, they have attracted considerable attention from a more fundamental and theoretical point of view, because the high Lewis acidity at the metal center is the source of singular structures and bonding (1-3). 

Chemical bonds are formed by electrons, and formation or breakage of bonds requires the migration of electrons. In broad terms, reactive chemical groups function either as electrophiles or as nucleophiles. Electrophiles are electron-deficient substances that react with electron-rich substances nucleophiles are electron-rich substances that react with electron-deficient substances. The task of a catalyst often is to make a potentially reactive group more reactive by increasing its electrophilic or nucleophilic character. In many cases the simplest way to do this is to add or remove a proton. 

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