HYDRAZINE Think of its IH remarkable potential as a powerful metals reductant
(H) He Be
Β
C
Ν
0
F
Ne
Na Mg
AI
Si
Ρ
S
CI
Ar
Li
Κ
Ca
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga Ge As
Se
Br
Kr
Rb
Sr
Y
Zr
Nb Mo
Tc
Ru
Rh
Pd
Ag
Cd
In
Sn
Sb
Te
I
Xe
Cs
Ba La*
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
TI
Pb
Bi
Po
At
Rn
Fr
Ra Act
*l_anthanides Ce
Pr
Nd Pm Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm Yb
Lu
Th
Pa
U
Np
Am
Cm
Bk
Cf
Es Fm Md No Lw
tActinides
Pu
D Metal reduced by hydrazine
One of the earliest uses of hydrazine was for the reduction of ferric oxide in boilers. Since then, research scientists have concentrated on more esoteric uses for this versatile diamine, such as organic ring closures and hydrogénations. Now attention is once again focused on hydrazine as a reducing agent for metals. And for good reason. Hydrazine is versatile. It will reduce most heavy metal compounds (including those of gold, silver and platinum) either to the metals themselves or to a lower valence. Hydrazine is powerful. The standard redox potential is a high 1.16 volts. And unlike the common reductant, hydrogen, hydrazine does not require high pressure to do the job. Hydrazine is economical. It's a small molecule, with a molecular weight of 32. Yet it has four reducing equivalents per mole. Pound for pound, that's better than most other reducing agents. Getting out of the red We said hydrazine has long been used to help control corrosion in boilers. Hydrazine forms a protective film of black iron oxide, Fe304, on the boiler walls. It does this both by oxidizing the iron and by reducing the non-protecting red oxide, Fe203. 6Fe203 + N2H4
> 4Fe304 + N2 + 2H 2 0
Nitrogen and water are the only byproducts in this reaction. Neither contributes dissolved solids to the system, a consideration that's also extremely
important in control of waste waters. Life in the effluent society Once it sufficed for R&D scientists to keep their companies from being caught up a technological creek. Now they're responsible for cleaning up the creek, too. Hydrazine is effective in removing chromâtes from waste waters. Cr04"
NoH,
Cr+ + +
OH"
Cr(OH)34
Toxic levels of heavy metal ions, such as copper, nickel and cobalt, are often present in waste streams from metal plating or stripping operations. Hydrazine can reduce these metallic ions, rendering them insoluble. The metals can then be recovered and re-used or disposed of properly. If you need to remove metal compounds from an effluent, hydrazine, used correctly, could let you do it while neither harming plant life nor adding harmful dissolved solids to your system. Other ions in the fire Hydrazine's reducing power is valuable for electroless plating of many metals and alloys onto metallic and non-metallic surfaces. For example, copper can be coated on glass to make circuit boards. Or nickel can be plated electrolessly onto copper and plastics. Usually, wear resistance and adherence of the metals to substrates are better. Hydrazine can reduce uranium from U (VI) to U (IV) and neptunium from Np (V) to Np (IV). These reductions are CIRCLE 30 ON READER SERVICE CARD
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C&EN July 27, 1981
useful in reprocessing of nuclear fuel, and in the extraction of uranium. If you need to prepare catalysts, you can easily reduce salts of platinum, palladium, rhodium or ruthenium to colloidal metals. You can etch silicon, which is particularly useful to reduce reflectivity in solar panels, and to make integrated circuitry. Or you can reduce selenium to an amorphous powder, which can be used for such applications as xerography, rectifiers and electrical equipment. There are many other uses in this vein, but you get the idea. (And maybe another idea or two on your own.) Reduce your metals problems to manageable proportions We've made it easy for you to find out if hydrazine can help you. We can give you comprehensive technical literature. We have a Databank that can get you pertinent information, fast. We'll send you samples to experiment with, if you like. And when you're ready to get serious about reducing, we've made it easier for you to get all the hydrazine you need. We recently tripled our capacity to 21 million pounds. Whatever you need, just ask. Write, on your company letterhead, to: Hydrazine Marketing Manager, Olin Chemicals, Dept. 2F-138HR, 120 Long Ridge Road, Stamford, CT 06904.
O l i n CHEMICALS
