Hydrazines isocyanates

Another type of polyol often used in the manufacture of flexible polyurethane foams contains a dispersed soHd phase of organic chemical particles (234—236). The continuous phase is one of the polyols described above for either slab or molded foam as required. The dispersed phase reacts in the polyol using an addition reaction with styrene and acrylonitrile monomers in one type or a coupling reaction with an amine such as hydrazine and isocyanate in another. The soHds content ranges from about 21% with either system to nearly 40% in the styrene—acrylonitrile system. The dispersed soHds confer increased load bearing and in the case of flexible molded foams also act as a ceU opener. 

This sulfonyl urea, prepared from an amino acid and p-tosyl isocyanate in 20-80% yield, is cleaved by alcohols (95% aq. EtOH, n-PrOH, or -BuOH, 100°, 1 h, 95% yield). It is stable to dilute base, to acids (HBr/AcOH or cold CF3CO2H), and to hydrazine. ... 

Phenylsemicarbazide has been obtained by the action of hydrazine hydrate on diphenylurea, phenylurethane,i phenyl isocyanate, or the potassium salt of dibenzohydroxamic acid. For its preparation, Curtius method of treating phenylurea with hydrazine liydratc is better Ilian either the older method of... 

Reaction of these polyols with an excess of isocyanate yields isocyanate terminated materials which are then chain extended by an amine such as hydrazine (NH2NH2) or ethylenediamine. The fibre is usually spun from solution in dimethylformamide. 

The chain extension step may then take place in the water phase. Hydrazine and ethylene diamine are commonly used chain extenders for waterborne urethane dispersions. The isocyanates react with the diamine chain extenders much faster than with the water, thus forming polyurea linkages and building a high molecular weight polymer. More detailed information regarding the synthesis and process of making waterborne polyurethane dispersions is found in Dieterich s review article [58]. 

Scheme 9 Synthesis of 1,3,4-oxadiazoles from acyl hydrazines and isocyanates...

Acid- and base-promoted methods have also been used in the syntheses of pyrazoles. Hydrogenation of methyl 2-Cbz(hydrazine)-3-hydroxy-4,4-dimethoxybutanoate 11 followed by cyclization in the presence of trifluoroacetic acid afforded the first asymmetric synthesis of the (4S,5.R)-5-carbomethoxy-4-hydroxy-A2-pyrazoline 12 <00TL8795>. Reaction of 2-nitrobenzyl triphenylphosphonium ylide (13) with aiyl isocyanates afforded 2-aryl-2H-indazoles 14 <00TL9893>. Base-promoted reaction of nitrobenzenes 15 with aryl imines 16 afforded aryl pyrazoles 17 . 

I-Cyanobenzocyclobctene, 48, 53 8-Cyanoethylhydrazine, from acrylonitrile and hydrazine, 48, 8 reaction with sulfuric acid, 48, 8 Cyanogen bromide, 45, 88 Cyahogen chloride, in preparation of chlorosulfonyl isocyanate, 46, 24 reaction with sulfur trioxide, 46, 24 7-Cvanoheptanal, 49, 27, 28... 

Phenyl isocyanate, with ethyl hydrazine-carboxylate to give 4-phenyl-l-car-bethoxysemicarbazide,51,122 Phenylmercuric acetate, with methallyl alcohol to yield 2-methyl-3-phenyl-propionaldehyde, 51, 17 1-PHENYL-1,3-PENTADIYNE, 50, 97 1-PHENYL-1,4-PENTADIYNE. 50, 97 a-Phenylpentanal, from 2-benzyl-4,4,6-trimethyl-5,6-dihydro-l,3(4H)-... 

Many organic chemicals are analyzed by RPC. These include various arylhydroxylamines as the N-hydroxyurea derivative with methyl isocyanate (614) alkyl- and alkoxy-disubstituted azoxybenzenes (6t5), n-alkyl-4-nitrophenylcarbonate esters ranging in length from methyl to octyl (616), 4-nitrophenol in the presence of 4-nitrophenyl phosphate (617), ben-zilic acid, and benactyzine-HCI using ion-pair chromatography (618), as well as aniline and its various metabolites (619), stereoisomers of 4,4 -dihydroxyhydrobenzoin (620), and aldehydes and ketones as the 2,4-dinitrophenylhydrazones (621). The technique has also been used to analyze propellants and hydrazine and 1,1-dimethylhydrazine were quantitita-vely determined (622, 623). 

B. 4-Phenyl-l-carbethoxysemicarbazide. In a 1-1. three-necked round-bottomed flask equipped with a liquid-sealed mechanical stirrer (Note 3), a constant-pressure dropping funnel, and a reflux condenser fitted with a drying tube containing silica gel is placed a solution of 52 g. (0.5 mole) of ethyl hydrazine-carboxylate in 550 ml. of dry benzene (Note 4). The solution is cooled in an ice bath, and the stirrer is started. To the solution is added 59.7 g. (55 ml., 0.5 mole) of phenyl isocyanate (Note 5) dropwise over a period of 45 minutes. After about one-half of the isocyanate has been added, a white precipitate of the product appears, and the reaction mixture becomes progressively thicker. After addition is complete the ice bath is removed, and the mixture is stirred at room temperature for 2 hours and then is heated under reflux for 2 hours. The suspension is allowed to cool to room temperature, and 4-phenyl-1-carbethoxysemi-carbazide is isolated by suction filtration, washed with 500 ml. of benzene, and dried in a vacuum desiccator. The yield is 108 g. (97%), m.p. 151-152°. The product is not further purified before being used in the next step. It may be recrystallized from ethyl acetate to yield white crystals, m.p. 154-155°, vmax 1645, 1687, 1797, and 3300 cm.-1 (Note 6). 

---