Unsaturation, test for

Unsaturation, tests for, 360, 1058 Unsymmetrical diaryls, synthesis of, 927-928 Uramil, 851... 

The tendency for a solvent to form deposits by polymerization of impurities such as olefins is measured by the test for potential gums . Olefin content can also be represented by the bromine index , which is a measure of the degree of unsaturation (see paragraph 3.4.1). 

Tests for Unsaturation. The above reactions are used as the general tests for the presence of double or triple bonds joining carbon atoms in an organic compound. 

Group VI. Concentrated sulphuric acid provides a simple test for the diflferentiation inter alia between (a) saturated paraffin and cyclic hydrocarbons and also simple aromatic hydrocarbons and (b) unsaturated hydrocarbons. 

Oxidizing agents also attack the double bond. When a reaction between an unsaturated compound and the permanganate ion occurs, the violet color of permanganate fades. This reaction, as well as reaction (29b) in which a color change also occurs, is used as a qualitative test for the presence of double bonds in compounds. 

Unsaturated polyester resins (UPRs) Uralkyd resins, 202 Urea-methylol reaction, 410 Urethane alkyds, 241 Urethane coatings, 202 Urethane elastomers, implanted, 207 Urethane foams, tests for, 244 Urethane gels, 205 Urethane-grade ATPEs, 223 Urethane-grade polyol types, 212 Urethane-grade raw materials, 246 Urethane hydrogel, preparation of, 250-251... 

The related unsaturated compounds, N-nitroso-1,2,3,6-tetra-hydropyridine and N-nitroso-1,2,3,4-tetrahydropyridine, have been tested for carcinogenicity and both were potent esophageal carcinogens, as is nitrosopiperidine. However, N-nitroso-1,2,3,6-tetrahydropyridine also produced liver tumors, whereas N-nitro-so-1,2,3,4-tetrahydropyridine also gave tumors of the forestomach and oropharynx. The difference in tumor spectrum between the two unsaturated isomers may be related to differences in metabolism. N-Nitroso-1,2,3,6-tetrahydropyridine isomerized to N-nitro-so-1,2,3,4-tetrahydropyridine in vivo, but the reverse reaction was not observed (49). 

The decolorisation of bromine, usually in CC14 solution, is one of the classical tests for unsaturation, and probably constitutes the most familiar of the addition reactions of alkenes. It normally proceeds readily in the absence of added catalysts, and one is tempted to assume that it proceeds by a simple, one-step pathway ... 

Thus, [HRh(C0)(TPPTS)3]/H20/silica (TPPTS = sodium salt of tri(m-sulfophenyl)phopshine) catalyzes the hydroformylation of heavy and functionalized olefins,118-122 the selective hydrogenation of a,/3-unsaturated aldehydes,84 and the asymmetric hydrogenation of 2-(6 -methoxy-2 -naphthyl)acrylic add (a precursor of naproxen).123,124 More recently, this methodology was tested for the palladium-catalyzed Trost Tsuji (allylic substitution) and Heck (olefin arylation) reactions.125-127... 

Other homochiral cyclic diol ligands such as (S,S)-148 for titanium alkoxide have also been tested for catalyzing phosphonylation of aldehydes, but it has been found that these diols are a poor choice of ligand for asymmetric phosphonylation.163 For most of the aldehydes studied (substituted benzaldehydes, a,/ -unsaturated aldehydes, and cyclohexanecarboxaldehyde), only moderate enantioselectivity was obtained (Scheme 2-62). 

In number of labs, the NIR is a rapid, non-destructive test. It is used (everywhere) for water determination. For the petroleum industry, it is routinely used for octane and betaine values, to determine levels of additives, and as a test for unsaturation. The polymer companies, in addition to identification, use NIR for molecular weight, cross-linking, iodine value (unsaturation) block copolymer ratios, and numerous... 

Pneumatic or hydraulic fracturing can occasionally be used to enhance the effective porosity (permeability) of unsaturated zones for SVE or air sparging. Successful soil fracturing is as much an art as a science. Pilot testing by experienced professionals is strongly recommended before performance guarantees are granted. 

The reaction with permanganate constitutes a valuable and much-used test for unsaturation in an organic compound. The substance is dissolved in cold alcohol, a few drops of sodium carbonate solution are added, and then a drop.of dilute permanganate solution. Rapid disappearance of the red colour indicates the presence of a double bond. The Baeyer test can also be carried out in pure glacial acetic acid, which is stable towards permanganate. Another method of detecting double bonds is by the decolorisation of bromine. As a rule, chloroform is used as solvent. 

As a last example of a molecular system exhibiting nonadiabatic dynamics caused by a conical intersection, we consider a model that recently has been proposed by Seidner and Domcke to describe ultrafast cis-trans isomerization processes in unsaturated hydrocarbons [172]. Photochemical reactions of this type are known to involve large-amplitode motion on coupled potential-energy surfaces [169], thus representing another stringent test for a mixed quantum-classical description that is complementary to Models 1 and II. A number of theoretical investigations, including quantum wave-packet studies [163, 164, 172], time-resolved pump-probe spectra [164, 181], and various mixed... 

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