The key difference between hydrazine and carbohydrazide is that hydrazine contains H2N-NH2 structure whereas carbohydrazide contains two hydrazine molecules attached to a single carbonyl carbon centre.

Hydrazine and carbohydrazide are chemical compounds containing H2N-NH2 units. A single unit of this chemical structure is called hydrazine while carbohydrazide has two of these structures attached to a carbonyl carbon centre.

CONTENTS

1. Overview and Key Difference
2. What is Hydrazine 
3. What is Carbohydrazide
4. Side by Side Comparison – Hydrazine vs Carbohydrazide in Tabular Form
5. Summary

What is Hydrazine?

Hydrazine is an inorganic compound having the chemical formula N2H4. We can name it as a simple pnictogen hydride, and it is a colourless and flammable liquid having an ammonical odour. This compound is highly toxic, and we should handle this substance with care. Its toxicity lowers if it is used in a solution, e.g. hydrazine hydrate.

Figure 01: Hydrazine Hydrate

Hydrazine is mainly useful as a foaming agent, which is important in preparing polymer foams. Moreover, it is useful as a precursor to polymerization catalysts, pharmaceuticals, and agrochemicals, as well as a long term storable propellant for in-space spacecraft propulsion.

There are many different routes for the production of hydrazine, including oxidation of ammonia via oxaziridines from peroxide, chlorine-based oxidations, etc. When considering the reactions of hydrazine, it shows acid-base behaviour where hydrazine can form a monohydrate that is denser than the anhydrous form, and it has basic (alkali) properties that are comparable with ammonia. In addition, hydrazine can undergo redox reactions because it can act as a reductant, giving byproducts which are typically nitrogen and water.

What is Carbohydrazide?

Carbohydrazide is an organic compound having the chemical formula H4N2-C(=O)-N2H4. This substance appears as a white, water-soluble solid that undergoes decomposition upon melting. There are a number of carbazides that has one or more N-H groups replaced by other substituents.

Figure 02: Structure of Carbohydrazide Molecule

We can produce this substance industrially through the treatment of urea with hydrazine. Also, we can prepare this substance through reactions of other C1 precursors with hydrazine, including carbonate esters.

Carbohydrazide molecule is a nonpolar molecule, and all the nitrogen centres in this molecule are at least somewhat pyramidal, which indicates a weaker C-N pi bonding.

When considering the uses of this compound, it is useful as an oxygen scrubber, precursor to polymers, useful in photography as a stabilizer, important in developing ammunition propellants, stabilize soaps, etc.

What is the Difference Between Hydrazine and Carbohydrazide?

Hydrazine and carbohydrazide are nitrogen-containing chemical compounds. The key difference between hydrazine and carbohydrazide is that hydrazine contains H2N-NH2 structure whereas carbohydrazide contains two hydrazine molecules attached to a single carbonyl carbon centre. Furthermore, we can categorize hydrazine as an inorganic compound and carbohydrazide as an organic compound because hydrazine has no carbon atoms in its molecules though carbohydrazide contains a carbonyl carbon centre.

Moreover, we can produce hydrazine using oxidation of ammonia via oxaziridines from peroxide, chlorine-based oxidations, etc. and carbohydrazide through the treatment of urea with hydrazine.

Below infographic shows more details of the difference between hydrazine and carbohydrazide in tabular form.

Summary – Hydrazine vs Carbohydrazide

Hydrazine and carbohydrazide are nitrogen-containing chemical compounds. The key difference between hydrazine and carbohydrazide is that hydrazine contains H2N-NH2 structure whereas carbohydrazide contains two hydrazine molecules attached to a single carbonyl carbon centre. Moreover, hydrazine occurs as a colourless liquid while carbohydrazide occurs as a white coloured solid substance.

Reference:

1. “Hydrazine.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine, Available here.
2. “Hydrazine.” An Overview | ScienceDirect Topics, Available here.

Image Courtesy:

1. “Sample of hydrazine hydrate” By LHcheM – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Carbohydrazide” By Edgar181 – Own work (Public Domain) via Commons Wikimedia

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