Ok a new synthesis, this first reference looks like one you MUST have if you want to work with this reagent. Safe handling and purification of aqueous hydrazine. Mitchell, J. W.; Harris, T. D.; Blitzer, L. D. Anal. Chem. (1980), 52(4), 774-6. Abstract Procedures are described for the safe handling and purifn. of aq. N2H4 solns. The purity of this reagent, prepd. by low temp. sublimation, was compared to other available reducing agents with the essential chem. and phys. properties for general use in anal. redns. Analyses by flameless at. absorption spectroscopy indicate that the prepd. N2H4 reagent is the purest, aq. phase, general purpose, anal. reducing agent currently known. Hydrazine from urea. West, Joseph Sidney. Brit. (1969), GB 1153483 19690529 Abstract N2H4 is made by the reaction of (NH2)2CO, NaOCl, and NaOH in 2 stages by using only a slight excess of NaOH. In the 1st stage concd. solns. of (NH2)2CO 1.0-1.1, NaOCl 1.0, and NaOH 0.1-0.3 moles are reacted at -10 to 10° to give NH2CONHCl. In the 2nd stage this is reacted with more NaOH (total 1.9-2.1 moles) at 90-110° in the presence of 0.2-1.0% of gelatin or glue. The 2nd stage is carried out with a small residence time, e.g. 30-60 sec. at 100°. Thus, 126 g. (2.1 moles) (NH2)2CO was dissolved in 189 g. water and 8 g. 50% NaOH soln. were added; then 1244 g. (2.0 moles) of a 12% soln. of NaOCl were added to this over 1-2 hrs. at -5°; after this 152 g. (3.8 moles) of NaOH as a 50% soln. and 1 g. of gelatin in 20 g. water were added and the mixt. was heated rapidly to 65-75°. The temp. then rose rapidly to 95-100° to give a 3.3% soln. of N2H4 in 75% yield. http://l2.espacenet.com/dips/viewer?PN=GB1153483&CY=ep&LG=en&DB=EPD Continuous manufacture of hydrazine and of its salts. Popa, Oliviu; Popa, Elena C. Rom. (1973), RO 52528 19730330 Patent written in Romanian. Abstract A continuous, time saving process, with higher yields is described in which cooling to 0° is unnecessary, 40% NaOH soln. is not used, and corrosion is reduced. Aq. 18% NaOH 1900, Cl gas 100, and aq. 25% urea 105 kg/hr are mixed at 20°. The urea soln. contained the catalysts 0.04 kg gelatin with either 2 kg MgSO4 or 0.4 kg MnSO4. Leaving the reactor at 95-100°, the soln. contained 2.3-2.7% hydrazine hydrate, representing a 90% yield based on Cl, and was neutralized with 98% H2SO4 to ppt. hydrazine sulfate. ALKALI CYCLING PROCESS FOR THE PRODUCTION OF HYDRATED HYDRAZINE FROM UREA Patent Number: CN1046328 (Written in Chinese) Abstract This invention relates to an alkali circulating process used in the preparation of hydrated hydrazine with sodium hypochlorite under alkaline condition by using urea as raw material. The reaction liquid resulted in the preparation of hydrated hydrazine is causticized with calcium hydroxide, and sodium carbonate is converted into sodium hydroxide and calcium carbonate. After calcium carbonate is separated out, hydrated hydrazine, caustic soda and sodium chloride, being in gaseous, liquid and solid phase separately, are separated during distillation and separation of hydrated hydrazine. Sodium chloride is recovered, caustic soda solution is reused. Modification of the urea process for production of hydrazine. Schoenbeck, Rupert; Kloimstein, Engelbert. Chem.-Ing.-Tech. (1974), 46(9), 391. Journal written in German. Abstract The process involves prepn. of NaOCl by reaction of dil. NaOH soln. with Cl2 followed by treating the mixt. with a 40% urea soln. After heating to .apprx.100° the hydrazine formed is extd. into Me isobutyl ketone and then into HCl. The hydrazine hydrochloride soln. thus formed is concd. by evapn. The max. yield is 80%. Isolation of hydrazine hydrate. Mundil, Rudolf. Ger. (1966), DE 1222900 19660818 Patent written in German. Abstract Hydrazine hydrate (I) reaction soln., prepd. from NH3 and NaOCl, was passed into a rotary evaporator fitted with 2 bubble cap plates. When the plates were charged with water, aq. I contg. 0.1-0.2 ppm. of chloride, and when charged with 5% NaOH, aq. I contg. 0.01% CO2, was obtained. Separation of hydrazine from aqueous solutions. DE 2056357 19720518 Patent written in German. Abstract N2H4, prepd. by reaction of Cl with NH3 via the chloramine in dil. aq. solns., was isolated from these solns. by treatment with MeCOEt, EtCHO, or Me2CO in the presence of hydrophilic substances, e.g. NaCl or CaCl2, making the reaction products H2O-insol. and forming 2 phases, sepg. the reaction product phase, and reconverting the reaction products into N2H4 and carbonyl compns. Thus, 200 ml NaCl-satd. soln. contg. 5.0 g N2H4.H2O was mixed with 50.8 g Me2CO at 50° to give a H2O-poor phase contg. 93.5% N2H4×H2O. Hydrazine and hydrazine hydrate. Schwarcz, Morton. US Patent 2537791 19510109 Abstract N2H4 (I) or N2H4.H2O (II) are produced by a 1-step distn. in a reducing atm. of a mixt. of a hydrazine salt and an amine, especially the alkylene polyamines, which boil higher than I or II, whichever the case may be; H2O is added to the mixt. to yield any desired concn. of II. Glycols, etc., may be added to reduce the viscosity of the distn. mixts. Thus, N2H4.H2SO4 260, (CH2NHCH2CH2NH2)2 240, and H2O 20 g., stirred 1 hr. at 60° and distd., give 75.5 g. of approx. 100% II, b70 59-67°. A Consideration of Hydrazine Syntheses Hac Ki Lee Journal of the Korean Chemical Society Volume 5, Number 1 (1961) It is important to study hydrazine because of the development of new uses for its derivatives. The Rasching method is the only satisfactory one for synthesizing hydrazine; it involves the oxidation of ammonia by sodium hypochlorite in the presence of some such catalyst as gelatin. Calcium hypochlorite was substituted for the sodium hypochlorite particularly in this work, applying agar-agar as catalyst. The results of the experiments are as follow: 1. The yield is proportional to the mole-ratio of ammonia to available chlorine in calcium hypochlorite and about 60% is obtained when the ratio is 20. 2. Agar-agar can be used as a catalyst and its proper concentration in the solution is 0.005%. 3. Proper concentration of available chlorine in the reaction solution is 0.23 mole/l. 4. The most effective condition for the reaction is a temperature of 60¡­65¡É. maintained for 20¡­25 min. 5. The reaction takes place equally well in either an open or closed container. 6. When calcium hypochlorite is applied in place of sodium hypochlorite, the yield of hydrazine is increased as much as 17%. 7. The yield of hydrazine is decreased by eliminating the suspension of Ca(OH)>2 which results from the use of calcium hypochlorite. 8. When Ca(OH)2 is added to Rasching process, the yield of hydrazine is raised normally. 9. The fact that some metal ions, such as Cu++, inhibit the formation of hydrazine was proved. 10. The suspension of Ca(OH)2 acted as a remarkable adsorbent for Cu++ like gelatin. The suspension of Ca(OH)2 which results from the use of calcium hypochlorite acts as a catalyst, absorbing metal ions, to increase the yield of hydrazine. So I think that calcium hypochlorite is a more efficient oxidant than sodium hypochlorite in hydrazine syntheses.