Semicarbazide hydrochloride is the hydrochloride salt of semicarbazide, a small hydrazide derived from carbonic acid. It is a white crystalline solid that dissolves readily in water and is used mainly as a synthetic building block in fine chemistry and as a reagent that converts aldehydes and ketones into crystalline semicarbazone derivatives.
Identity and Typical Specification
| Parameter | Typical value |
|---|---|
| Product name | Semicarbazide hydrochloride |
| Synonyms | Aminourea hydrochloride; semicarbazide HCl |
| CAS number | 563-41-7 |
| EINECS | 209-247-0 |
| Molecular formula | CH5N3O · HCl |
| Molecular weight | 111.53 g/mol |
| Appearance | White crystals or crystalline powder |
| Assay | ≥ 99.0% by titration |
| Melting point | 173–177 °C |
| Solubility | Freely soluble in water, soluble in hot ethanol |
| Packing | 25 kg fibre drum with inner liner |
| Shelf life | 24 months in unopened packaging |
Chemical Behaviour
The molecule combines a hydrazide group with an amide group on the same carbon, and the hydrochloride form keeps the free base stable, crystalline and easy to weigh. In acidic or mildly acidic media it condenses with aldehydes and ketones to give semicarbazones, which are crystalline solids with sharp melting ranges and are therefore useful for isolating and identifying carbonyl compounds. Neutralisation releases the free base, which is the reactive species in most condensation and cyclisation steps. As a hydrazide it also behaves as a nucleophile towards acid chlorides, esters and isocyanates.
Manufacturing and Quality Control
Semicarbazide hydrochloride is produced by reacting hydrazine hydrate with urea to build the semicarbazide skeleton, followed by salt formation with hydrochloric acid. The crude salt is dissolved, treated with activated carbon, filtered and recrystallised to give white crystals, which are then dried and milled to the agreed particle size. Release testing normally covers assay by titration, melting range, loss on drying, water content by Karl Fischer titration, clarity and colour of an aqueous solution, heavy metals and residue on ignition. Each batch is issued with a certificate of analysis, and a safety data sheet is available for transport and handling purposes.
Main Applications
Pharmaceutical intermediates: an intermediate for nitrofuran-type antibacterial actives and for other hydrazide-based synthetic routes.
Pesticide and agrochemical intermediates: a building block for heterocyclic ring construction in crop protection chemistry.
Analytical chemistry: a derivatisation reagent for aldehydes and ketones, used to confirm carbonyl identity through melting point determination.
Fine chemicals and research: a reagent for heterocycle synthesis, hydrazone preparation and polymer additive work.
Storage, Stability and Handling
Keep the material in a tightly closed container in a dry, well-ventilated store at ambient temperature, away from oxidising agents, strong acids and strong bases. The salt is hygroscopic, so opened drums should be resealed promptly to prevent caking and assay drift. Avoid generating dust during weighing and charging, provide local exhaust ventilation where dust is likely, and wear chemical goggles, impervious gloves and suitable protective clothing. Wash thoroughly after handling. The compound is an irritant to skin, eyes and the respiratory tract, and it must not be allowed to enter drains or watercourses.
Frequently Asked Questions
Q: What is semicarbazide hydrochloride used for?
It is used as an intermediate in pharmaceutical and agrochemical synthesis and as a laboratory reagent that converts aldehydes and ketones into crystalline semicarbazone derivatives.
Q: What is the CAS number of semicarbazide hydrochloride?
The CAS registry number is 563-41-7, with EINECS number 209-247-0 and molecular weight 111.53 g/mol for the formula CH5N3O · HCl.
Q: Why is the hydrochloride form preferred over the free base?
The salt is a stable, non-volatile crystalline solid that is easier to weigh, store and ship than the free base, and it releases the reactive base in situ when neutralised.
Q: How should the product be stored before use?
Store it sealed in a dry, ventilated place at ambient temperature, away from oxidisers and from strong acids or bases. Reseal opened containers promptly because the salt is hygroscopic.
Q: What is the typical assay of commercial material?
Standard commercial grades are supplied at 99.0% minimum by titration, with a melting range between 173 and 177 °C and a water content controlled by Karl Fischer titration.
Q: What are the main safety precautions?
Treat the material as an irritant: avoid dust formation, use local exhaust ventilation, wear goggles, gloves and protective clothing, and keep it out of drains and watercourses.
