Reactive dying

The reaction of 1-phenyl-4-vinylpyrazole 90a with the less reactive die-nophile MP was conducted at 150° under pressure for 5 days, affording the indazole 93 and a mixture of isomers 94a and 95a (86T6683). These 1 2 adducts were obtained by a Diels-Alder cycloaddition followed by a nonregioselective ene reaction. 

Catalases Catalyse the decomposition of hydrogen peroxide, important before reactive dying or printing of peroxide bleached fabrics and yarn... 

Copolymerization involves the reaction of at least two different monomers A and B. In the case of chain copolymerization, the reactivity ratios and are important, aiid rg = / bb BA di re /cy die... 

The flux of flie adsorbed species to die catalyst from flie gaseous phase affects die catalytic activity because die fractional coverage by die reactants on die surface of die catalyst, which is determined by die heat of adsorption, also determines die amount of uncovered surface and hence die reactive area of die catalyst. Strong adsorption of a reactant usually leads to high coverage, accompanied by a low mobility of die adsorbed species on die surface, which... 

In the case of nitrobenzene, the electron-withdrawing nitro group is not able to stabilize the positive charge in the complex intermediate. In fact, it strongly destabilizes die intermediate. This destabilization is greatest in the o- and />-intermediates, which place positive charge on the nitrosubstituted caibon. The meta transition state is also destabilized relative to that for benzene, but not as much as the ortho and para transition states. As a result, nitrobenzene is less reactive than benzene, and the product is mainly the meta isomer. 

Stereoelectronic factors are also important in determining the stmcture and reactivity of complexes. Complexes of catbonyl groups with trivalent boron and aluminum compounds tend to adopt a geometry consistent with directional interaction with one of the oxygen lone pairs. Thus the C—O—M bond angle tends to be in the trigonal (120-140°) range, and the boron or aluminum is usually close to die carbonyl plane. ... 

In the absence of die polyether, potassium fluoride is insoluble in benzene and unreactive toward alkyl halides. Similar enhancement of solubility and reactivity of other salts is observed in the presence of crown ethers The solubility and reactivity enhancement result because the ionic compound is dissociated to a tightly complexed cation and a naked anion. Figure 4.13 shows the tight coordination that can be achieved with a typical crown ether. The complexed cation, because it is surrounded by the nonpolar crown ether, has high solubility in the nonpolar media. To maintain electroneutrality, the anion is also transported into the solvent. The cation is shielded from interaction with the anion as a... 

In the discussion of the syn- and anft-norbomenyl tosylates (p. 312), it was pointed out that, relative to 7-norbomyl tosylate, the reactivities of the syn and anti isomers were 10 and 10, respectively. The high reactivity of the anti isomer was attributed to participation of die carbon-carbon double bond. What is the source of the 10 factor of acceleration in the syn isomer relative to the saturated model ... 

When strips of reactive metals such as zinc are placed in water a potential difference, die electromotive force (emf), is set up die metal becomes negatively charged due to die transfer of zinc ions to die solution and die build-up of electrons on die metal. The metal strips or rods are termed die... 

The ease with which an atom gains or loses electrons is termed die electronegativity of die element. Tabulation of die elements in order of ease hy which diey lose electrons is called die electrochemical series and is shown in Table 6.10. Chapter 4 explains die importance of diis to die formation and control of coiTosion, and Chapter 6 discusses die relevance to predicting reactivity of metals towards water and their potential to become pyrophoric. 

HIWAY-ROADWAY are two models which compute die hourly concentrations of non-reactive pollutants downwind of roadways and predict pollutant concentrations within two hundred meters of a highway, respectively. 

Ky, for glyceraldehyde-3-pho.sphate is calculated on die basis diat only 3.8% of die substrate in soludon is unhydrated and dierefore reactive widi the enzyme. 

Studies of die structures of cuprate species were initiated to elucidate die niedi-anisnis by wbidi tliey interact witli substrates and to understand dieit special reactivities. tn die early days tliese investigaiions were restricted to solution studies by spectroscopic tediniques. It was not until 1982 dial tlie dtst example of a cuprate species - [iCu Pbi-jiLiiTHFj))] - was stiuctutally diatacterlzed by X-tay crystal stiucture deterniination [ 100] ivide infra). It sbotild be noted tliat most of diese studies, reviewed previously [29, 45, 101], were limited to "simple" alkyl and aryl derivatives. 

II is beyond die scope of diis diapler lo discuss die special reactivities associaled witli eadi specibc lype of ctiprale, tliese are covered in odier diapters in tliis book. Here, we w dl concenlrale on die various stractiiral tiiolifs of organoctiprales in organic syudiesis. 

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