Hydrazine

Hydrazine Hydrates

Hydrazine derivatives are used in the manufacture of herbicides and fungicides, as well as plant growth regulators. From tranquilizers to the primary drug for controlling tuberculosis, hydrazine derivatives have proven to be effective ingredients for a number of pharmaceuticals.

Used as an oxygen scavenger in boiler water, Scav-Ox® 35% hydrazine solution reduces oxidation in both low and high pressure steam systems.

In fact, hydrazine is the best material that can be used for protection against oxidation in super critical boilers operating at pressures up to 3500 psi.

Currently, the plastics industry uses hydrazine derivatives in the creation of blowing agents and polymerization initiators. Use of these derivatives is also being investigated for the formulation of polymers.

Terminology
Hydrazine solution strength is usually given as the percent contained hydrazine. However, when hydrazine and water are mixed, a monohydrate (N2H4.H20) is formed through hydrogen bonding. Therefore, the amount of hydrazine in a solution can also be designated as the percentage of hydrazine monohydrate. There is a simple relationship between the two designations, based on their molecular weights.

Hydrazine has a molecular weight of 32 and the monohydrate has a molecular weight of 50. The ratio of their weight is 32/50 or 0.64. Therefore, 100% monohydrate would contain 32/50 or 64% hydrazine. This is the reason 100% hydrazine hydrate can be used interchangeably with 64% contained hydrazine by weight.

To avoid confusion caused by dual terminology, Arch always expresses hydrazine content in terms of contained hydrazine. Since other companies may not follow this convention, users should ascertain which terminology applies when reference to hydrazine solution concentration is involved.

Physical Properties

	Weight % N2H4
	35%			51.2%	54.4%	64%
Property	Scav-Ox®	Scav-Ox® Plus	Scav-Ox® II	51.2%	54.4%	64%
Density @ 25°C (g / ml) (lb / gal)	1.02 8.52	1.01 8.504	1.02 8.51	1.028 8.58	1.031 8.59	1.032 8.61
Viscosity @ 25°C (cp)	1.02	1.40	-	1.44	.45	1.5
Boiling Point @ 760 mm Hg(C)	109.4	109.5	109.4	119.0	119.8	120.1
Freezing Point (°C)	-65	-65	-65	-57	-57	-51
Flash Point, COC (°C)	None	None	None	93	89	72
Fire Point, COC (°C)	None	None	None	102	96	74
Heat of Formation, Liq. (kcal/mole)	-	-	-	-	8.140	10.300
Specific Heat @ 130°F(Btu/lb/°F) @ 54°C(cal/g/°C)	- -	- -	- -	- -	- -	.0838 .0838
Solubility in Water	Completely miscible	Completely miscible	Completely miscible	Completely miscible	Completely miscible	Completely miscible
Vapor Pressure @ 25°C(mm Hg)	22	22	22	2-5	2-5	2-5

Compatability of Materials

Materials Of Construction	Hydrazine Concentration in Aqueous Solutions
Materials Of Construction	< 10%	35%^a	51.2%	54.4%	64%
Stainless Steel - 304L - 347 - 316	S S S^b	S S S^b	S S S^b	S S S^b	S S S^b
Cold Rolled Steel	S	NR	NR	NR	NR
Copper	NS	NS	NS	NS	NS
Brass	NS	NS	NS	NS	NS
Teflon^c	S	S	S	S	S
Polyethylene	S	S	S	S	S
Aluminum	NS	NS	NS	NS	NS

a - Scav-Ox®, Scav-Ox® II and Scav-Ox® Plus are 35% solutions.
b - Up to 150°F
c - Trademark of E.I. dupont de Nemours, Inc.
S - Generally Satisfactory.
NS - Not suitable (due to Hydrazine decomposition or to adverse effects of the solution on the materials of
construction).
NR - Not recommended.