Isocyanate piperazine

A new ionic polymeric polycarbamate was synthesized after steps of polyurethane chemistry using 3-iso-cyanatemethyl-3,5,5-trimethylcyclohexyl isocyanate, 2,5-dimethyl-2,5-dihydroperoxyhexane, 1,6-butanediol, 2,4-tolylenediisocyanate, and N,N -bis(j3-Hydroxy-ethyOpiperazine [27]. Modification of the nitrogen of the piperazine ring into quaternary ammonium salt by treatment with methyliodide gave the MPI high electroconductivity. 

Isocyanates Ketones PRE-CD with l-(2-methoxy-phenyl) piperazine PRE-CD with 220... 

Finally, ortho aminoesters have been used to produce 7-deazaxanthines. For example ethyl 2-amino-5-phenyl-l//-pyrrole-3-carboxylate is first treated with 2-chloroethyl isocyanate in refluxing toluene. The resulting urea derivative is then allowed to react with l-(2-methoxyphenyl)piperazine and cyclized to the expected pyrrolo[2,3-,7 pyrimidin-2,4(177,377)-dione <2006BMCL150>. 

Occupational air (total isocyanates) Air collected/derivatized through 1-(2-methoxyphenyl)piperazine in toluene acetylation evaporation HPLC with UV detection 0.2 mol/ sample 96% average NIOSH 1984 NIOSH Method 5505... 

A solution of phenoxyethyl isocyanate (89 g, 0.55 mol) in toluene (450 ml) is generated in situ (see step 7) and cooled to -20°C. To the solution is added a solution of l-(3-chlorophenyl)-4-(3-hydrazinopropyl)piperazine (131.2 g, 0.49 mol) in 100 ml toluene at the speed that the internal temperature is below -10°C. After the addition is completed the mixture is stirred for 30 min at -20°C and for 1.5 hours at 0°C and quenched with 150 ml 1 N NaOH solution. The mixture is stirred at 0°C for 10 min and filtered through celite. The filtrate is saturated with NaCI and separated. The aqueous layer is extracted with 100 ml toluene and the combined toluene solution was dried over Na2S04, filtered and concentrated to give a viscous oil. A small amount sample was purified by column chromatography (5% MeOH/CH2CI2) to give a colorless oil. The crude... 

Arylpiperazinylethylthieno[3,2-d]pyrimidinediones 209 were obtained from o-aminoester 189 (R2 = R3 = H, Y = Me) in three steps. The latter was reacted with 2-chloroethyl isocyanate to give the 2-chloroethylurea 207. This urea was then treated with various phenyl-substituted piperazines to afford ureas 208. These ureas were cyclized to the thienopyrimidinedi-ones 209 by heating in methanolic potassium hydroxide (88JMC1786). 

Press et al. (87USP4670560 88JMC1786) reacted aminoesters 292 with 2-chloroethyl isocyanate in refluxing toluene and obtained the 2-chloroethylureas 304. These ureas were further reacted with various N-phenyl-substituted piperazines in either THF or propan-2-ol and in the presence of sodium iodide and sodium bicarbonate. The resulting substituted ureas 305 were then heated in methanolic potassium hydroxide to afford the thieno[3,4-d]pyrimidinediones 306. 

Primary or secondary aminopyrazines may be converted directly into ureido- or thioureidopyrazines by treatment with isocyanates or isothiocyanates primary aminopyrazines may also be converted into such products indirectly via the corresponding isocyanato- or isothiocyanatopyrazines piperazines may be converted into 1/4-carbamoyl- or thiocarbamoylpiperazines by treatment with isocyanates, A-nitrourea, or isothiocyanates and aminopyrazines may be converted into guani-dinopyrazines by treatment with. S -methylisothiourcas or cyanamide. These processes (and some subsequent intramolecular cyclizations or other reactions) are illustrated in the following examples ... 

POLY(IMINO(l-OXO-l,6-HEXANEDIYL)) see PJY500 POLYMALEIC ACID see PJY850 POLYMERS of EPICHLOROHYDRIN and 2,2-BIS(4-HYDROXYPHENYL)PIPERAZINE see ECM500 POLYMERS, WATER-INSOLUBLE see PKA850 POLYMERS, WATER-SOLUBLE see PKA860 POLYMETHYLENEPOLYPHENYL ISOCYANATE see PKBIOO... 

IJC468, 78IJC(B)ioi5). Treatment of the piperazine ester (482) with phenyl isocyanate followed by refluxing hydrochloric acid gave the dioxo derivative (483) (62HCA2383). 

The intermediate sulfonyl isocyanate (107) reacts with the co-haloalcohols (108) to give N-carboxylsulfamates (109) which readily cyclise on treatment with triethylamine or sodium hydride to yield 2-oxazolidones (110) (Scheme 46). However, when (109) (Ar = Ph, X = Br) was heated with sodium hydride in boiling THF, the 2-oxazolidone (110) was not isolated, but rather the phenoxysul-fonylpiperidazine (111) (Scheme 46). The formation of the piperazine derivative (111) is believed to involve the initial formation of the 2-oxazolidone (110) which... 

Here, the authors treated phenylethylaniine 35 with 1.25 equiv. of 4-methox-yphenyl isocyanate 36 to form a crude reaction mixture of product urea 37 and excess isocyanate. Subsequently, the isocyanate impurity was removed either by quenching with N,N-dimethylaminoethylamine followed by cation exchange, or by quenching with 1-(2-hydroxyphenyl) piperazine followed by anion exchange. 

Certain secondary amine compounds are commonly used for chemical derivation of isocyanates which, like phosgene, form substituted urea compounds amenable to chromatographic determination. One of the most common of these reagents is 1—(2—pyridyl)-piperazine (PYP) PYP reacts on a one-to-one basis with isocyanate compounds yielding a stable urea derivative which can be quantified specifically and sensitively with reversed phase, high performance liquid chromatography (HPLC) and ultraviolet absorbance detection. 

A-(2-AMINOETHYL) PIPERAZINE (140-31-8) Combustible liquid (flash point 199°F/ 93°C). Aqueous solution is a strong base. Incompatible with strong oxidizers, organic anhydrides, acrylates, alcohols, aldehydes, alkylene oxides, substituted allyls, cellulose nitrate, cresols, caprolactam solution, epichlorohydrin, ethylene dichloride, isocyanates, ketones, glycols, nitrates, phenols, vinyl acetate. Exothermic decomposition with maleic anhydride. May increase the explosive sensitivity of nitromethane. Attacks aluminum, copper, magnesium, nickel, zinc, or their alloys, and galvanized steel. 

Treatment of the piperazine ester 72 with phenyl isocyanate, followed by refluxing with hydrochloric acid, gave the perhydrodioxo derivative 73. Other perhydro derivatives (74) have been obtained by cyclization of anilinomethylpiperazines with aldehydes. " ... 

Catalytic hydrogenation of perhydropyrazino[2,3-ft]pyrazines provides monocyclic piperazines. In other ways the compound behaves as a tetramine, forming a tetrahydrochloride and reacting with four moles of acetic anhydride, phenyl isocyanate, and phenyl isothiocyanate. ... 

Henriks-Eckerman, M.-L., Valimaa, J., and Rosenberg, C., Determination of airborne methyl isocyanate as dibutylamine or l-(2-methox3fphenyl)piperazine derivatives by liquid and gas chromatography, Ana/yrf, 125, 1949-1954, 2000. 

Ellwood P.A., Hardy H.L. and Walker R.F. (1981) Determination of atmospheric isocyanate concentrations by high-performance thin-layer chromatography using l-(2-pyridyl)-piperazine reagent. Analyst, 106, 85-93. 

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