Mercaptan resins

Poly(vinylbenzyl mercaptan) has been described by several authors. The synthesis always follows the same path chloromethylation of polystyrene followed by reaction with thiourea and hydrolysis of the isothiuronium salt 1,53,55,63-65). The redox properties of a polymer obtained from chloromethylated styrene-divinylbenzene copolymers have been evaluated (3). Redox capacities givrai for mercaptyl resins were determined to be 2. W>-5.27 milliequivalents of iodine reduced per gram of (dry) resin in aqueous potassium iodide. The oxidized form of the resin could be easily reduced with 10% aqueous bisulfite fmr a complete redox cycle. Recently polyvinylbenzyl mercaptan resins were prepared directly by treating chloromethylat polystyrene with KSH in dimethyl formamide (66). 

ZeoHte-based materials are extremely versatile uses include detergent manufacture, ion-exchange resins (ie, water softeners), catalytic appHcations in the petroleum industry, separation processes (ie, molecular sieves), and as an adsorbent for water, carbon dioxide, mercaptans, and hydrogen sulfide. 

Paint and varnish manufacturing Resin manufacturing closed reaction vessel Varnish cooldng-open or closed vessels Solvent thinning Acrolein, other aldehydes and fatty acids (odors), phthalic anhydride (sublimed) Ketones, fatty acids, formic acids, acetic acid, glycerine, acrolein, other aldehydes, phenols and terpenes from tall oils, hydrogen sulfide, alkyl sulfide, butyl mercaptan, and thiofen (odors) Olefins, branched-chain aromatics and ketones (odors), solvents Exhaust systems with scrubbers and fume burners Exhaust system with scrubbers and fume burners close-fitting hoods required for open kettles Exhaust system with fume burners... 

Low molecular weight liquid nitrile rubbers with vinyl, carboxyl or mercaptan reactive end groups have been used with acrylic adhesives, epoxide resins and polyesters. Japanese workers have produced interesting butadiene-acrylonitrile alternating copolymers using Ziegler-Natta-type catalysts that are capable of some degree of ciystallisation. 

Both amines and acid anhydrides are extensively used cross-linking agents. The resins may also be modified by reacting with other polymers containing hydroxyl or mercaptan groupings, e.g. 

A number of studies have evaluated the toxicity of pulping hquors, in particular the black liquors generated from Kraft mills. Table 8 shows a partial representation of toxicity data compiled by the NCASI (National Council of the Paper Industry for Air and Stream Improvement) and McKee and Wolf for Kraft mill pulping wastewaters [15,16]. The table indicates that hydrogen sulfide, methyl mercaptan, crude sulfate soap, and salts of fatty and resin acids are particularly... 

Black oil should be a pure petroleum product free from fatty oils, fatty acids, resins, soaps, or other nonhydrocarbons. Sediment and sludge, insoluble in paraffin naphtha, should not exceed 12% when determined by the methods of the American Association of State Highway Officials. The product should be a distilled or fractionated oil, and should contain no oil-well water or residue therefrom. The product should be free of or contain no more than traces of naphthenic acids, naphthenes, mercaptans, soluble sulfide, and volatile sulfur derivatives. The oil should flow freely from the tank car at temperatures above 32 F. 

Bisphehol A Diglycidyl Ether Resin Isopropyl Mercaptan Isopbopyl Percarbonate Isopropyl Percarbonate P-Cymene... 

The liquid polymer is converted to the rubbery state by reagents that react with mercaptan (-SH) and side groups of the polymer segments by oxidation, addition or condensation to effect sulfide (-S-S-) bond formation. The oxidation reactions are exothermic and accelerated by an alkaline environment. The most commonly employed oxidizing agents which are suitable for curing liquid polymers are cobalt or manganese or lead octoate, p-quinonedioxime and di- or tri-nitrobenzene. Epoxy resin also reacts with liquid polysulfide polymers by addition in the presence of an aliphatic or aromatic amine and polyamide activator as shown in Equation 5.8 ... 

The same procedure is used for the formation of resins 2 and 8 by reaction of the nitroarenes with the resin-bound [3-alanine or mercaptan/ amine linker, respectively. The o-fluoronitroarenes (Fig. 3) are dissolved in DMSO or NMP (at a concentration between 1.5 and 2 M) and added to the resin, followed by diisopropylethylamine (10 equivalents) and additional DMSO or NMP (if required) to ensure resin solvation. Although many nitroarenes react rapidly at room temperature, in a library format the resin/nitroarene mixture is heated overnight at 50° to help achieve equivalent reaction kinetics between different monomers. Under the same conditions, some o-chloronitroarenes are synthetically useful. The extent of the reaction can be assessed qualitatively (or quantitatively, if desired) by carrying out a ninhydrin test to check for the presence of free amine. In any case, the resins are acetylated with five equivalents of acetic anhydride/pyridine/DMF (1 1 10) for 20 min to cap any unreacted amine. 

The synthesis of 3-benzyl-2-phenylthiazolidin-4-one (47, Fig. 21) demonstrates the mercaptane scavenging applicability of the aminoethanethiol resin (48). Benzaldehyde is allowed to react with benzylamine in the presence of mercapto acetic acid (49) in toluene under refluxing conditions. 

Reaction of Resin-Bound Iron Complex (54) with Alkyl Mercaptans, Thiophenols, and Phenols (Fig. 9)31. Sodium thiolates are prepared analogously to the alkoxides from thiol and sodium hydride, except that dry DMF is used as a solvent. The substitution on the polymer-bound arene (54) is performed at 70° in DMF within 16 h. The resin is filtered and washed with DMF (2 x 50 ml), MeOH (2 x 50 ml), H20 (2 x 50 ml), MeOH (2 x 50 ml), and CH2CI2 (3 x 50 ml) and then dried in vacuo at 40° to yield a red resin. 

The polyaddition reaction is the most commonly used type of reaction for the cure of epoxy resins. The curing agents used in this type of reaction have an active hydrogen compound, and they include amines, amides, and mercaptans. With this reaction mechanism, the most important curing agents for adhesives are primary and secondary amines containing at least three active hydrogen atoms and various di- or polyfunctional carboxylic acids and their anhydrides. 

The polymercaptans can also be used to accelerate the curing of epoxy resins systems blended with polyamines, amidoamines, or amines. The other curatives serve as the base to accelerate mercaptans, and the mercaptans react rapidly, generating the heat to accelerate the cure with the other hardener. 

Polysulfide resin, on the other hand, does not have fast and low-temperature curing properties. It is used as more of a flexibilizer than a curing agent. However, polysulfide resins do have mercaptan groups, and these enter into the epoxy cure reaction. 

FIGURE 5.12 Reaction of mercaptan with an epoxy resin.19... 

Poly sulfide compounds that are compatible with epoxy resins are liquid elastomers at room temperature. The most significant commercial resin of this type is LP-3 from Toray. The predominant product is a mercaptan-terminated liquid polymer (LP) that contains approximately 37% bound sulfur (see Fig. 7.2). It is the high concentration of sulfur linkages that provides these products with their unique chemical properties. A sulfur odor is noticeable during processing, making ventilation important. 

There are a number of silane adhesion promoters available, and they differ in the nature of their reactivity to the resin or adhesive. Silanes may be produced with amine, epoxy, mercaptan, and other functionalities. Some examples are given in Table 10.1. 

Dynamic Mechanical Properties of Mercaptan-cured Resin.188... 

The mercaptan hardener is one of a very few hardeners which can cure the resin at low temperature even below the freezing point in a few minutes using basic catalysts such as amines. There are only very few studies of the curing reaction mechanism and the physical properties of the cured resin available 42 45). 

The mechanism of curing of epoxy resin with mercaptan has been proposed by Kamon44 and has been based on the work by Danehy46 ... 

Terpolymer Resins. DBPF was dissolved in a mixture of styrene, acrylonitrile, and mercaptan (Table I). About one-tenth of this solution was added to a solution of sodium alkylbenzene sulfonate emulsifier (Nacconal NRSF, 2 parts) in deionized water (180 parts) at 60°C. Potassium persulfate (0.3 part) was added, followed by the remaining monomer mixture at a rate consistent with temperature control (60°C.) Gentle agitation and a nitrogen atmosphere were maintained throughout the polymerization. The latex was maintained at 60 °C. until a solids determination indicated no further conversion (6—8 hours total polymerization time). 

Table I shows the fracture energies for epoxy resin which have been toughened by liquid polymers with different functional groups. Clearly the selectivity of the functional groups is more important than the reactivity. MTBN, with the most reactive mercaptan end groups, had the least improvement in fracture energy the cured material is trans-...

The product from Step 1 (0.013 mol), benzyl mercaptan (0.039 mol) and Amberlyst RTM-15 resin (1.0 g) in chloroform were refluxed 20 hours. The mixture was then treated with an additional 1.5 g resin and refluxed an additional 4 hours. The mixture was cooled, filtered, concentrated, triturated with hexane, and a solid collected by filtration to give a total product mixture of 19%. 

Sodium sulfhydride (NaSH) is a much better reagent for the formation of thiols (mercaptans) from alkyl halides than H2S and is used much more often. It is easily prepared by bubbling H2S into an alkaline solution, but hydrosulfide on a supported polymer resin has also been used. " The reaction is most useful for primary halides. Secondary substrates give much lower yields, and the reaction fails completely for tertiary halides because elimination predominates. Sulfuric and sulfonic esters can be used instead of halides. Thioethers (RSR) are often side products. The conversion can also be accomplished under neutral conditions by treatment of a primary halide with F and a tin sulfide, such as PhsSnSSnPhs. An indirect method for the preparation of a thiol is the reaction of an alkyl halide with thiourea to give an isothiuronium salt (119), and subsequent treatment with alkali or a... 

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