Hydroxypropyl radicals, reaction

It is important to note that the rate of reaction of alkyl radicals with thiols does not simply correlate with the exothermicity of the reaction, i.e., with the BDE of the C-H bond to be formed. For example, the tertiary 2-hydroxypropyl radical reacts more readily with thiols than the primary hydroxymethyl radical, and this reacts even faster than the methyl radical (Table 6.4). The reason for this surprising behavior has been discussed in terms of the charge and... 

Cationic Starches. The two general categories of commercial cationic starches are tertiary and quaternary aminoalkyl ethers. Tertiary aminoalkyl ethers are prepared by treating an alkaline starch dispersion with a tertiary amine containing a p-halogenated alkyl, 3-chloro-2-hydroxypropyl radical, or a 2,3-epoxypropyl group. Under these reaction conditions, starch ethers are formed that contain tertiary amine free bases. Treatment with acid easily produces the cationic form. Amines used in this reaction include 2-dimethylarninoethyl chloride, 2-diethylaminoethyl chloride, and A -(2,3-epoxypropyl) diethylamine. Commercial preparation of low DS derivatives employ reaction times of 6—12 h at 40—45°C for complete reaction. The final product is filtered, washed, and dried. 

Fragmentation processes of photoinitiators form a number of volatile products, which may contribute to indoor air pollution. Benzaldehyde and alkyl-substituted benzalde-hydes are usual components, because Norrish-I is the most important reaction for cleavage. Awell known example is l-phenyl-2-hydroxy-2-methyl-propane-l-one (PHMP). a-Cleavage generates two radicals in the first step. The benzoyl radical may recombine to form benzil, reduction of PHMP leads to l-phenyl-2-methy 1-1,2-propane and acetone, and recombination of the 2-hydroxypropyl radical gives 2,3-dimethyl-2,3-butanediol... 

Table 10.10 The importance of the reduction potential with regard to the reaction of onium ions with 2-hydroxypropyl radicals [26].

Monomers like iron (III) methacrylate [CH2=C(CH3)-COO] 3Fe and tributyltin methacrylate have been synthesized [3]. They undergo free radical polymeriz-ation/copolymerization with other acrylates such as cyclohexyl, 2-ethoxyethyl, 2-hydroxyethyl and 2-hydroxypropyl. Synthesis of a metailo-macrocyclic acrylic monomer is illustrated by the reaction between a metallophthalocyanine tetracarbonyl chloride (1) and 2-hydroxyethyl methacrylate (2-HEMA) [4]... 

A chain reaction has also been observed with organic peroxides.1 It has been reported that the 2-hydroxypropyl-(2) radical (derived from isopropyl alcohol) may undergo a chain reaction, even at neutral pH, where the equilibrium concentration of ketyl ion is very low (see Table I), but this chain reaction is not very efficient. Using available data,99,1 the rate constant for the propagating reaction in the N20-2-hydroxypropyl-(2) radical system is calculated to be 150 M-1. s-1. 

Although BDE is by far not the only factor that determines the kinetics of H-transfer reactions, within a given series of simple alkyl radical a correlation seems to hold (Table 6.4). In polymers, where the lifetime of the polymer-bound radicals may be long, radical transfer reactions by intramolecular H-abstrac-tion (primary - secondary —> tertiary) are common (Chap. 9.4). In general, whenever a system starts with a mixed radical system (e.g., in the reaction of OH with 2-PrOH 2-hydroxy-prop-2-yl and 2-hydroxypropyl) a steady-state is approached which is dominated by the lower-energy radical [here 2-hydroxy-prop-2-yl, cf. reaction (21)]. This process is favored by low initiation rates and high substrate concentrations, and these two factors determine whether such an H-transfer manifests itself is also in the final products. 

Quaternary ammonium alkyl ethers are prepared similarly an alkaline starch is reacted with a quaternary ammonium salt containing a 3-chloro-2-hydroxypropyl or 2,3-epoxypropyl radical. Alternatively, such derivatives can be prepared by simple quaternization of tertiary aminoalkyl ethers by reaction with methyl iodide. Sulfonium (107) and phosphonium (108) starch salts have also been prepared and investigated. Further work has explained the synthesis of diethylaminoethyl starch (109) as well as the production of cationic starches from the reaction of alkaline starch with... 

In the above condensation resist designs, the phenolic resin offers a reaction site as well as base solubility. Self-condensation of polymeric furan derivatives has been utilized as an alternative crosslinking mechanism for aqueous base development (Fig. 126) [375]. The copolymer resist is based on poly[4-hydroxy-styrene-co-4-(3-furyl-3-hydroxypropyl)styrene], which was prepared by radical copolymerization of the acetyl-protected furan monomer with BOCST followed by base hydrolysis. The furan methanol residue, highly reactive toward electrophiles due to a mesomeric electron release from oxygen that facilitates the attack on the ring carbons, readily yields a stable carbocation upon acid treatment. Thus, the pendant furfuryl groups serve as both the latent electrophile and the nucleophile. Model reactions indicated that the furfuryl carbocation reacts more preferentially with the furan nucleus than the phenolic functionality. 

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