Activation resin formation

Teratogenic activity. Resin, administered orally to pregnant rabbits at a dose of 1 mL/ kg, was active k Alcohol extract of the dried leaves, administered intragastrically to pregnant rats at a dose of 125 mg/kg from days 7 to 16 of gestation, was active. The fetuses showed several gross abnormalities, visceral anomalies, and skeletal mal-formations . Water extract of the dried... 

A number of simple and inexpensive materials catalytically promote the cobalt-carbonylation (Reaction 2) in aqueous solution. These include ion-exchange resins, zeolites, or special types of activated carbon. Formation of the active catalyst in a separate reactor is thus economically feasible. The mechanism of this catalysis has not yet been elucidated and seems to differ for each promoter mentioned. After an induction period during which the cobalt fed to the reactor is partially retained by the promoter, fully active materials have absorbed cobalt carbonyl anion Co(CO)4 (ion exchange resins), Co2+ cation (zeolites), or a mixture of Co2+, cobalt carbonyl hydride, and cluster-type cobalt carbonyls (activated carbon). This can be shown by analytical studies (extraction, titration, and IR studies) of active material withdrawn from the reactor. 

The rate constant was calculated from the linear portion of each plot for the four temperatures used. The temperatures and rate constants are plotted in the Arrhenius equation in Figure 2. A reasonably straight-line relationship is obtained and an activation energy for / -resin formation of 49 kcal is obtained from the slope of the plot... 

Other o-nitrophenol-containing resins have been prepared with the aim of increasing the distance between the reactive center and the macromolecular backbone, which should accelerate the active ester formation by achieving an easier approach of the reagents. Thus, the Friedel-Crafts alkylation of styrene-divinyl-benzene copolymer with 4-hydroxy-3-nitrobenzyl chloride promoted by aluminium trichloride gave 4-hydroxy-3-nitrobenzylated polystyrene (70) (approximately 30% of the aromatic rings of the polymer were substituted according to elemental... 

Scheme 7.29 Synthesis of a progesterone-derived amide via a solid-supported active ester formation using N-hydroxysuccinimide resin 89.

For specific applications, such as paper release resins, we have developed two types of photochemically activated platinum hydrosilylation catalysts. The complexes 1 are highly useful in silicone resin formation using Si-H and Si-Vi or Si-H and Si poxy ftmctional polysiloxanes under thermal or UV irradiation conditions. 

A similar concept for site-selective thiolysis of peptide bonds via backbone peptide bond activation can be found in Jensen s work (Fig. 18) [115]. The key step involves activation of the carboxy group of a Glu side chain by PyBrOP (19), resulting in the on-resin formation of the pyroglutamyl imide moiety. The activation renders the imide C-N bond susceptible to thiolysis, after which protected peptide thioesters were released from the solid support. 

Cyclization is known to release resin-bound compounds without a linker. Hydantoin ring formation releases resin-bound compounds smoothly, producing interesting hydantoin derivatives with potential medicinal or biological activity. Resin-bound alkenes reacted with nitrile oxides that were generated with Mukaiyama s method from nitroalkane (Scheme 11.48). The isoxazolines were cleaved from the resin via ahydantoin formation upon heating under basic conditions. 

The immobilization of pyranose oxidase and horseradish peroxidase in activated resins associated with a spectrophotometric reaction based on the formation of Bindshedler s green (k = ITl nm) permits the determination of sorbitol in a FIA format with a detection limit of 1.2 pmol L [62]. Prior to enzyme conversion, samples suffer an online treatment based on passage through a cleanup column filled with a strongly basic anion exchange resin, positioned after the injection valve. This step was of the utmost importance during the analysis of serum samples and can also be exploited for the analysis of foods and... 

Many attempts have been made to reduce the ammoniacal and sulfurous odor of the standard thioglycolate formulations. As the cosmetics market is very sensitive to the presence of impurities, odor, and color, various treatments of purification have been claimed to improve the olfactory properties of thioglycolic acid and its salts, such as distillation (33), stabilization against the formation of H2S using active ingredients (34), extraction with solvents (35), active carbon (36), and chelate resin treatments (37). 

The solvent is then evaporated, and the unconverted sterol is recovered by precipitation from an appropriate solvent, eg, alcohol. The recovered sterol is reused in subsequent irradiations. The solvent is then evaporated to yield vitamin D resin. The resin is a pale yeUow-to-amber oil that flows freely when hot and becomes a brittie glass when cold the activity of commercial resin is 20 30 x 10 lU/g. The resin is formulated without further purification for use in animal feeds. Vitamin D can be crystallized to give the USP product from a mixture of hydrocarbon solvent and ahphatic nitrile, eg, benzene and acetonitrile, or from methyl formate (100,101). Chemical complexation has also been used for purification. 

ButylatedPhenols and Cresols. Butylated phenols and cresols, used primarily as oxidation inhibitors and chain terrninators, are manufactured by direct alkylation of the phenol using a wide variety of conditions and acid catalysts, including sulfuric acid, -toluenesulfonic acid, and sulfonic acid ion-exchange resins (110,111). By use of a small amount of catalyst and short residence times, the first-formed, ortho-alkylated products can be made to predominate. Eor the preparation of the 2,6-substituted products, aluminum phenoxides generated in situ from the phenol being alkylated are used as catalyst. Reaction conditions are controlled to minimise formation of the thermodynamically favored 4-substituted products (see Alkylphenols). The most commonly used is -/ fZ-butylphenol [98-54-4] for manufacture of phenoHc resins. The tert-huty group leaves only two rather than three active sites for condensation with formaldehyde and thus modifies the characteristics of the resin. 

Possible uses for these polyhydroxy compounds include the preparation of alkyd-type resins with polybasic acids, the formation of ester plasticizers, and the preparation of surface-active agents. 

Water-emulsifiable vehicles contain emulsifiers that may act as plasticizers after film formation, affecting the hardness. Water-soluble vehicles usually contain a neutralizing amine, the primary purpose of which is to solubihze the resin. These amines can influence the drying properties as they tend to complex the metal drier, thus affecting the catalytic activity. Acceptable results are usually obtained with trialkylamines such as dim ethyl eth a n o1 amine, trimethyl amine, and aminomethylpropan o1 (7). 

The formation of a phenolic resin is often formally separated into two steps, though it probably should be three. If we use a three-step model, the first step is activation of the phenol or aldehyde. The second step is methylolation, and the third is condensation or chain extension. In addition to the clarity provided by the formalism, these steps are also generally separated in practice to provide maximum control of exothermic behavior, with the strategy being to separate the exotherm from each step from that of the others as much as possible. As there are significant differences in the activation step and in the details of the methylolation and condensations steps of novolacs and resoles, we will treat the two types separately. 

Unsaturated polyesters The formation of the coating occurs in situ by the reaction between polyester resin and styrene, activated by a catalyst such as organic peroxide. The main use as coatings is in the formation of glass fiber or glass flake, reinforced plastics. 

Dynamic DSC scans of resole resins show two distinguishable reaction peaks, which correspond to formaldehyde addition and die formation of edier and metiiy-lene bridges characterized by different activation energies. Kinetic parameters calculated using a regression analysis show good agreement widi experimental values.75... 

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