Reactive fixation compounds

Substituents in the 4-position of these compounds are also a to a multiply-bonded nitrogen atom, but because of bond fixation they are relatively little influenced by this nitrogen atom even when it is quaternized (333). This is similar to the situation for 3-substituents in isoquinolines, cf. Chapter 2.02. In general, substituents in the 4- and 5-positions of imidazoles, thiazoles and oxazoles show much the same reactivity of the same substituents on benzeneoid compounds (but see Section 4.02.3.9.1). 

There are reactive softeners, some of which are N-methylol derivatives of long-chain fatty amides (10.241) while others are triazinyl compounds (10.242). The N-methylol compounds require baking with a latent acid catalyst to effect reaction, whereas dichloro-triazines require mildly alkaline fixation conditions. The N-methylol compounds are sometimes useful for combination with crease-resist, durable-press, soil-release and water-repellent finishes. In this context, the feasibility of using silane monomers such as methyltri-ethoxysilane (10.243), vinyltriethoxysilane (10.244), vinyl triace tylsilane (10.245) and epoxypropyltrimethoxysilane (10.246) in crosslinking reactions to give crease-resist properties and softness simultaneously has been investigated [492]. 

Interest in acid-fixing reactive dyes has remained active because of their environmentally attractive features (section 1.7). The freedom from competing hydrolytic reactions potentially offers exceptionally high fixation, extreme stability of the dye-fibre bonds and complete suitability of the unfixed dyes for recycling. In contrast to conventional reactive dyes, sensitisation problems arising from reaction with skin proteins are not anticipated. Unlike the haloheterocyclic reactive dyes, there is no risk of release of AOX compounds to waste waters. Heavy metals are not involved in the application of acid-fixing reactive dyes, nor are the electrolytes or alkalis that normally contaminate effluents from conventional reactive dyeing. 

The highly reactive compound disodium 4,4,-bis(dichlorotriazinylamino) stilbene-2,2 -disulphonate (7.126 known as DAST or T-DAS), an important intermediate in the manufacture of stilbene-type fluorescent brightening agents (section 11.6.1), has been evaluated recently as a crosslinking agent for the fixation of dyes with nucleophilic groups. Compound 7.126 was applied to cotton simultaneously with the hydrolysed form of Cl... 

The conversion of CO + H2 (syn-gas) to hydrocarbons and oxygenates (Fischer-Tropsch chemistry)119 is of considerable industrial importance and recently the activation and fixation of carbon monoxide in homogeneous systems has been an active area for research.120,121 The early transition elements and the early actinide elements, in particular zirconium124 and thorium,125 126 supported by two pentamethylcyclopentadienyl ligands have provided a rich chemistry in the non-catalytic activation of CO. Reactions of alkyl and hydride ligands attached to the Cp2M centers with CO lead to formation of reactive tf2-acyl or -formyl compounds.125,126 These may be viewed in terms of the resonance forms (1) and (2) shown below. 

Inorganic Salt Preservatives. Inorganic compounds used to formulate wood preservatives are normally water soluble. As a result, the salts deposited in the wood are susceptible to leaching unless they are transformed to insoluble compounds or are chemically fixed to the wood substrate. Indeed, such conversions do occur as a result of interactions between some of the salts and the wood substrate. Both single element and multicomponent reactions are involved in the fixation mechanisms copper and chromium are the most reactive of the possible components. 

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