تحضير الهيدرازين المائي من اليوريا وهايبوكلوريت الصوديوم

Abstract

Abstract Many methods for production of Hydrazine Hydrate are stated in the literature. The best method was selected ( urea process ) depending on availability of raw materials in Al-Furat State Co. for Chemical Industries, local market, method of applicability and feasibility. The synthesis of hydrazine from urea and sodium hypochlorite was studied (Urea Process). Concentration of reactants ( 6 - 14% NaOCl , urea 34.1 g , NaOH 47.8 g , gelatin ratio 0 - 0.57 g) , reaction temperature ( 90 – 110) ᵒC were studied to determine their effects on the production of hydrazine in order to obtain higher concentration , the mixing rate was (120 rpm). Hydrazine detection and determination test has been done in the labs of Al-Furat State Co. using colorimetric method and oxidation with potassium iodate method. Additionally, samples were tested by iodemetric method in the lab of T.P.S. (Treatment Water Unit in Al-Mussayab Power Station). The results showed that highest concentration of hydrazine hydrate of (52%) was obtained at (14%) NaOCl, urea (34.1g), NaOH (47.8g), gelatin (0.47g) , and reaction temperature of (100 ᵒC) at (120 rpm).

Keywords : hydrazine hydrate, raschig process, urea process, hydrazine detection, oxygen scavenger.

Introduction Hydrazine, NH2NH2, the simplest diamine and parent of innumerable derivatives, was prepared in (1887) by Curtius as the sulfate salt from diazoacetic ester. Thiele (1893) suggested that the oxidation of ammonia or urea with hypochlorite should yield hydrazine. F.Rasching (1906) first demonstrated this process, variations of which constitute the chief commercial methods of manufacture today[1] . The first large-scale use of hydrazine was a fuel for the rocket-powered German ME-(163) fighter plane during World War ll. Production in the United States began in (1953) at the Lacke Charles, Louisiana, plant of the Olin Crop., a facility with a rated capacity of (2040) metric tons/year. From this modest beginning, noncommunist capacity has grown to a (1979) level of (35,000 t/year) [1] . Hydrazine is a strong reducing agent; it is used for corrosion control in boilers and hot-water heating systems. It is also an oxidizing agent under suitable conditions. With two active nucleophilic nitrogens and four replaceable hydrogens, hydrazine is the starting material for many derivatives [1] .

Experimental Part Materials: Urea from local markets. Sodium hypochlorite &Sodium hydroxide from Al-Furat State Co. Gelatin from local Markets. Distilled water. Equipments and Devices: •Fume hood. • Magnetic stirrer. • Beakers. •Conical flasks. •Chiller. • Watch glass. •Electrical Heater. •Funnel. • Thermometer. • Stirring rod •Electrical scale. • Burette. • Colorimeter (Neo-comparator / Lovibond/England ).

Procedure : The synthesis of hydrazine from urea and sodium hypochlorite was studied . A- Preparation of NaOCl/NaOH Solution: 1- Place ( 355 ml) of (10%) NaOCl solution in conical flask and cool to (8°C). 2- Using a magnetic stirrer add NaOH to the cooled NaOCl solution (47.8g) , then chill to (5-8)°C . B- Preparation of Urea/Gelatin Solution: 1- Place 3mL of water in a (25ml) beaker. Add ( 0.47g ) of gelatin, breaking it and dispersing with a stirring rod. Add (15mL) of boiling water and stir the gelatin until dissolved. 2- Add ( 20ml) of hot water to a ( 250ml) beaker. Then add (34.1g) of urea and stir until dissolved. 3- Pour the gelatin solution into the urea solution and stir until mixed. C- Preparation of Hydrazine Solution: This was done in the hood as hydrazine is toxic. 1- Place the stir bar in the (1-liter) flask and place on the magnetic stirrer/hotplate. Insert the funnel in the flask. 2- Cool hypochlorite solution to ( 5-8)°C , set the stir bar at (120 rpm) , then mix with urea/gelatin solution. Immediately raise the stir bar speed as required. 3- The reaction initiates immediately and a snow white foam will rise to fill the flask to about the ( 900ml) level. After a few minutes the foam will begin to subside and the solution will turn translucent orange , then heat up . Turn down the stir rate to prevent foam generation. Apply heat steadily to drive the solution to boiling (approximately 100°C). The color will fade to a pale yellow then to almost clear. The clear color indicates the endpoint of the reaction. At this point heating is stopped. 4- Remove the overflow funnel and place a small watch glass over the mouth of the flask to exclude air. The watch glass will allow any (CO2) to escape and also prevent a vacuum from forming [2]. Detection and Determination of Hydrazine Hydrate: 1-Detection and determination of hydrazine by Colorimetric method [3]. 2-Determination of Hydrazine by oxidation with Potassium Iodate [4]. 3-Determination of Hydrazine by Iodimetric Method in the lab of T.P.S. (Treatment Water Unit in Al-Mussayab Power Station).

Results& Discussion Firstly, quantitative analysis for the prepared samples has been done using colorimetric method by Colorimeter in Al-Furat Co. lab. Obviously, the result was positive where they showed a yellow color that indicates the formation of hydrazone compounds. The effect of gelatin ratio on hydrazine percentage was studied. Different amount of gelatin has been taken at the end of each experiment and the amounts of hydrazine produced are shown in table No.1. The effect of hypochlorite concentration on the percentage of hydrazine is shown in table No.2. Table No.1 shows the effect of gelatin ratio on the percentage of hydrazine. Table (1) shows two conclusions; the first one there is no change in the percentage of hydrazine (24%) at gelatin ratio of (0.24 g) . Secondly, it is clearly there is a significantly increase in percentage of hydrazine (28%) at gelatin ratio of (0.47g) and (0.57g) attributed to inhibition of gelatin for side reactions. Table no.2 shows the effect of sodium hypochlorite concentration on the percentage of hydrazine. Table (2) shows two conclusions ; the first one the percentage of hydrazine decrease whenever sodium hypochlorite concentration decreased , Secondly, the highest percentage of hydrazine (52%) at sodium hypochlorite concentration (14%) attributed to oxidizing power of sodium hypochlorite which works as oxidizing agent to urea. Table (1) The effect of gelatin ratio on hydrazine percentage %. hydrazine%* Gelatin used in gram 24 0 24 0.24 28 0.47 28 0.57 Table (2) The effect of NaOCl % on hydrazine% product. Hydrazine%* NaOCl% 52 14 40 12 40 10 20 8 20 6 References 1- Kirk-Othmer, , "encyclopedia of chemical technology" 3 rd vol , join Wiley and sons.inc. , USA(1984). 2-https://sites.google.com/site/ecpreparation/hydrazine-preparation 3-HELLIGE GMBH Handbook of Visual Colorimetry (Instructions for Analysis) A 10 Printed in Germany (1985). 4-Arthur I.Vogel, D.Sc. (Lond.), D.I.C., F.R.I.C., A Text-Book of Quantitative Inorganic Analysis Including Elementary Instrumental Analysis , Third Edition