Formaldehyde free radical

The cyanoacryhc esters are prepared via the Knoevenagel condensation reaction (5), in which the corresponding alkyl cyanoacetate reacts with formaldehyde in the presence of a basic catalyst to form a low molecular weight polymer. The polymer slurry is acidified and the water is removed. Subsequendy, the polymer is cracked and redistilled at a high temperature onto a suitable stabilizer combination to prevent premature repolymerization. Strong protonic or Lewis acids are normally used in combination with small amounts of a free-radical stabilizer. 

A waterborne system for container coatings was developed based on a graft copolymerization of an advanced epoxy resin and an acryHc (52). The acryhc-vinyl monomers are grafted onto preformed epoxy resins in the presence of a free-radical initiator grafting occurs mainly at the methylene group of the aHphatic backbone on the epoxy resin. The polymeric product is a mixture of methacrylic acid—styrene copolymer, soHd epoxy resin, and graft copolymer of the unsaturated monomers onto the epoxy resin backbone. It is dispersible in water upon neutralization with an amine before cure with an amino—formaldehyde resin. 

Formalin [Formaldehyde], 55, 45 Formamide,AGV-dimethyl-, 55, 58 Free radical cychzation, 55, 57... 

Formaldehyde-to-phenol ratios, 404 V-Formyl amines, 158 Fourier transform infrared (FTIR) spectrometry, 116, 300, 387, 407-408 Fradet, Alain, 17 Free-radical copolymerization, 59 Friedel-Crafts acrylation polymerization, 332-334... 

What is the initial source of the free radicals that are so important for oxidant development Calvert and McC igg attempted to answer this question by evaluating the many proposed reactions with their detailed chemical model. Although the actual importance of any particular source will depend on the concentration of pollutants assumed and the time of irradiation they found for a typical mixture (nitric oxide nitrogen dioxide rra/is-2-butene, formaldehyde acetaldehyde carbon monoxide water and methane) that the following reactions were the most important radical sources ... 

Kinetic studies on the oxidation of glutamate by manganese(III) in aqueous sulfuric acid, acetic acid, and pyrophosphate suggest different mechanisms for each case. In all cases there is evidence for the involvement of free radicals and in the case of acetic acid and pyrophosphate media a chelated intermediate is postulated. Simultaneous Mn(III)/Mn(IV)-mediated reaction is observed in the oxidation of formaldehyde by... 

Photolytic. Photolysis products include carbon monoxide, ethylene, free radicals, and a polymer (Calvert and Pitts, 1966). Anticipated products from the reaction of acrolein with ozone or OH radicals in the atmosphere are glyoxal, formaldehyde, formic acid, and carbon dioxide (Cupitt,... 

The carboxylate free radical rapidly decarboxylates to -hydroxy or -amine radicals which are oxidized by oxygen to formaldehyde or acetaldehyde. Substitution of Mn in the goethite structure reduces the photoredox reactivity of goethite. 

Figures 4.26, 4.27, and 4.28 show typical UV absorption spectra for some simple aldehydes and ketones (Rogers, 1990 Martinez et al., 1992 see also Cronin and Zhu, 1998, for n-pentanal). Formaldehyde stands out from the higher aldehydes and ketones in that it has a highly structured spectrum and furthermore, the absorption extends out to longer wavelengths. The latter difference is particularly important because the solar intensity increases rapidly with wavelength here (Chapter 3.C.1) and hence the photolysis rate constant for HCHO and the rate of production of free radicals...

One example of the use of chambers to study the effects of addition of copollutants is seen in Fig. 16.9 (Pitts et al., 1976). As discussed earlier, one source of H02 free radicals in ambient air is the photolysis of formaldehyde ... 

The compounds obtained by the replacement of ring sulfur by carbon, as in the case of penicillins, show somewhat improved antibiotic properties. A free radical— based route has been described for the conversion of fermentation derived cephalosporins to their carbocyclic derivatives. The first step in this sequence consists of the condensation of the cephalosporin sulfone (36-1) with formaldehyde and dimethyla-mine the initial product from the Mannich-like reaction consists of the exomethylene derivative at the position adjacent to the activating sulfone. The product is treated in situ with phenylselenol to give the Michael adduct (36-2). This fragments with an extmsion of sulfur dioxide when heated with the free radical initiator AIBN in the presence of tributyltin hydride the reaction can be envisaged as leading to the... 

---