1-Piperazine ethyl acetate

After evaporation of the solvent, a very thick, colorless oil is obtained. This base is dissolved by 200 ml of absolute ethanol and the quantity of HCI to obtain the dihydrochioride is added. It is left for a few hours over ice, dried, washed with approximately 100 ml of anhydrous ether in order to obtain 190 to 195 grams of 1-[2-phenyl-2-methoxy]-ethyl-4-[3-phenyl-3-hydroxy] -propyl-piperazine dihydrochioride after drying at 60°C in vacuo. The yield is 80%. It is recrystallized from absolute ethanol. The product is in the form of white crystalline powder, soluble in water, slightly soluble in alcohol, insoluble in ethyl acetate. 

Dichlorophenyl)-l-piperazinopropionitrile (20.0 g), acetic anhydride (100 ml), anhydrous sodium sulfate (12.0 g) and a 50% solution of Ni-Raney (6 ml) are hydrogenated at 60.0 pounds per inch at 60°C in a Parr apparatus. After about half an absorption of hydrogen is complete. The reaction mixture is cooled, the is filtered and the solution is concentrated to small volume in a rotating evaporator. The residue is treated with NaOH solution and extracted several times CH2CI2. The organic layer is washed, dried and evaporated. The residue is crystallized from ethyl acetate. 14.0 g of the l-(3-acetylaminopropyl)-4-(2,5-dichlorophenyl)piperazine are obtained, melting point 114°C. 

The reaction mixture was cooled to 90°C and diluted with ethyl acetate. The solid was filtered off, washed with ethyl acetate and dried. So the l-[5-(l-benzopyran-2-one)]piperazine hydrochloride was obtained, melting point 250°C (dec. recrystallized from ethanol). 

Nitroindole-2-carboxylic acid (0.86 g), l-[3-(N-isopropyl)amino-2-pyridinyl]piperazine (0.43 g), l-(ethyl)-3-(dimethylaminopropyl)carbodiimide (0.45 g) and THF (4 ml), were stirred at 20-25°C for 3 hr then the reaction mixture was dissolved in chloroform (50 ml) and extracted with saturated aqueous sodium bicarbonate, saline, dried over anhydrous sodium sulfate and concentrated under reduced pressure. Purification by flash column chromatography (200 g silica) eluting with ethyl acetate/hexane (50/50), the appropriate fractions were pooled and concentrated to give l-[5-nitroindolyl-2-carbonyl]-4-[3-(l-methylethylamino)-2-pyridinyl]piperazine, mp 153°-154°C. 

A cold, stirred solution of 1-phenyl-piperazine in tetrahydrofuran was treated all at once with [3-(2-methyl-5,6-dimethoxy)indolyl]glyoxalyl chloride. There was an immediate voluminous precipitate of a white crystalline solid which was removed by filtration. The filtrate was taken to dryness and the residual light brown gum was stirred and shaken with water, ethyl acetate and acetic acid. The mixture was warmed on a steam bath and the resulting solid was collected after cooling in an ice bath thus affording l-[(3-(2-methyl-5,6-dimethoxy)indolyl)glyoxalyl]-4-phenylpiperazine as a near white solid, melting point 163°-174°C. 

A solution of ethyl 5-chloro-2-oxo-3-benzo-thiazolineacetate (4.0 grams) in 1-(2-hydroxyethyl)piperazine is heated at 100°C for 24 hours. After cooling, the resulting mixture is extracted with chloroform. The chloroform extract is washed with water and shaken with 10% hydrochloric acid. The hydrochloric acid layer is washed with chloroform, made alkaline with 10% sodium hydroxide solution and extracted with chloroform. The chloroform extract is washed with water, dried over magnesium sulfate and concentrated. The residual oil (5.5 grams) is allowed to stand to form crystals, which are recrystallized from a mixture of ethyl acetate (40 ml) and ethanol (15 ml) to give 3-[4-(2-hydroxyethyl)-l-piperazinylcarbonylmethyl]-5-chloro-2(3H)-benzothiazolinone (3.2 grams) as colorless crystals, MP 159° to 161°C. 

Sample preparation Sample + 400 pL 5 mM DBD-PZ -i- 70 mM diethylphosphorotyan-idate in MeCN, react for 6 h, inject a 1 xL aliquot. (DBD-PZ prepared from 123 mg 4-(N, N-dimethylaminosulfonyl)-7-fluoro-2,l,3-benzoxadiazole in 20 mL MeCN added dropwise to 129 mg piperazine in 20 mL Me(DN at room temperature, stir for 30 min, evaporate under reduced pressure, dissolve residue in 50 mL 5% HCl, extract three times with 20 mL ethyl acetate, discard ethyl acetate extracts, adjust pH of aqueous solution to 13-14 with 5% NaOH, extract five times with 50 mL ethyl acetate, combine extracts, wash with 20 mL water, dry over anhydrous sodium sulfate, evaporate under vacuum to give DBD-PZ as orange crystals, mp 121-2°.)... 

A mixture of cyanomethyl acrylate, piperazine hexahydrate, a little hydroquinone, and ethyl acetate heated 3 hrs. at 70° l,4-bis(cyanomethyl)piperazine. Y 82.7%. F. e. s. R. Harada and Y. Kinoshita, Bull. Chem. Soc. Japan 40, 2706 (1967). 

Ethyl 5-chloro-2-oxobenzothiazoline acetate 1 -(2-Hydroxyethyl)piperazine... 

A series of compounded flame retardants, based on finally divided insoluble ammonium phosphate together with char-forming nitrogenous resins, has been developed for thermoplastics.23 These compounds are particularly useful as intumescent flame-retardant additives for polyolefins, ethylene-vinyl acetate, and urethane elastomers. The char-forming resin can be, for example, an ethyle-neurea-formaldehyde condensation polymer, a hydroxyethyl isocyanurate, or a piperazine-triazine resin. Commercial leach-resistant flame-retardant treatments for wood have also been developed based on a reaction product of phosphoric acid with urea-formaldehyde and dicyandiamide resins. 

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