Reactive Reagents

Reactive reagents generally aid in film formation, forming bonds to the substrate, crosslinking, and curing. Examples of this class of additives include metallic driers, such as zinc or tin salts, to aid in crosslinking [10,18] curing catalysts and accelerators photoinitiators and adhesion promoters. 

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Cl increases the Lewis acidity of boron making it a more reactive reagent... 

Even with this highly reactive reagent excellent selectivity was achieved for one of two similar alcohols. 

Catalysis, leading to less severe operating conditions, the use of a less reactive reagent, or the opportunity to eliminate or reduce the use of a hazardous solvent. 

Less reactive reagents may act more selectively. Thus androst-4-ene-3,11,17-trione (7) is converted into the 3-monoenamine (8) with morpholine and into the 3,17-dienamine (9) with pyrrolidine.The greater reactivity of pyrrolidine as compared to piperidine and morpholine has been attributed to the greater stability associated with a double bond exocyclic to a 5-mem-bered ring which facilitates the dehydration step. ... 

Me- SiCl also affects the stereoselectivity of 1,2-additions to carbonyl compounds [ 133]. Witli the aid of suitable activators, these mildly reactive reagents show selec-tivities unattainable by the conventional reagents, as ilustrated below for Me- SiCl-dependent Chemoselectivity fEq. 10.13) [134]. 

Trimethylhyctdzinium iodide is a novel, highly reactive reagent for at via VNS, as shown in Eq 9 49, in which the regioselecdviry is different from that obtained v/ith other reagents... 

Sulphoxides are reduced by the more powerful metal hydride reducing agents14, but the less reactive reagents such as sodium borohydride are ineffective. Recently, Yoon25 has... 

The conversions observed followed the sequence of reactivity known from batch experiments carried out in advance. For example, only 15% conversion was found for the less reactive reagent benzoylacetone in the micro reactor experiment, while 56% was determined when using the more reactive 2,4-pentanedione (batch syntheses 78% and 89%, respectively) [8]. Using the stopped-flow technique (2.5 s with field applied 5.0 s with field turned off) to enhance mixing, the conversions for both syntheses were increased to 34 and 95%, respectively. Using a further improved stopped-flow technique (5.0 s with field applied 10.0 s with field turned off), the conversion could be further enhanced to 100% for the benzoylacetone case. For the other two substrates, diethyl malonate and methyl vinyl ketone, similar trends were observed. 

Halogenations are strongly catalyzed by mercuric acetate or trifluoroacetate. These conditions generate acyl hypohalites, which are the active halogenating agents. The trifluoroacetyl hypohalites are very reactive reagents. Even nitrobenzene, for example, is readily brominated by trifluoroacetyl hypobromite.19... 

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