Semicarbazide Hydrochloride | CAS 563-41-7

semicarbazide hydrochloride. Its chemical formula is CH₅N₃O·HCl and its molecular weight is 111.53 g/mol. Semicarbazide hydrochloride is a derivative of urea, which is an organic compound that contains two amine groups and a carbonyl group. Semicarbazide hydrochloride belongs to the class of carboxylic acid hydrazides, which are compounds that have a carboxylic acid group (COOH) replaced by a hydrazine group (NHNH₂).

Physical Properties

Some of the physical properties of semicarbazide hydrochloride are:

Color: white to light cream
Shape: crystalline powder
Odor: odorless
Density: 1.286 g/cm³
Melting point: 176 °C (decomposes)
Boiling point: 235.3 °C at 760 mmHg
Flash point: 66.5 °C
Solubility: soluble in water (>100 g/L at 15 °C), insoluble in absolute alcohol and ether
Refractive index: 1.544 (estimated)
Electrical conductivity: not available

Chemical Properties

Some of the chemical properties of semicarbazide hydrochloride are:

Stability: stable under normal conditions, decomposes when heated above melting point
Reactivity: reacts with strong oxidizing agents and bases
Acidity: weakly acidic, pKa = 5.0
Redox potential: not available

Preparation Methods

Semicarbazide hydrochloride can be prepared by various methods, such as:

Reacting carbon monoxide with hydrazine at high pressure and temperature in the presence of a metal carbonyl catalyst
Reacting nitrourea with hydrogen in the presence of a hydrogenation catalyst, hydrochloric acid and an inert solvent
Reacting urea with hydrazine hydrate at reflux temperature and then adding anhydrous hydrogen chloride
Reacting hydrazine sulfate with potassium cyanate and then adding hydrochloric acid

One example of a preparation method is given below:

 $O C (N H_{2})_{2} + N_{2} H_{4} - > O C (N H_{2}) (N_{2} H_{3}) + N H_{3} O C (N H_{2}) (N_{2} H_{3}) + H C l - > O C (N H_{2}) (N_{2} H_{3}) * H C l$

Urea (60.1 g, 1 mole) and 64% aqueous hydrazine solution (55 g, 1.10 moles) were placed in a 250 ml, 3-neck flask and heated at reflux (115°-120° C.) for three hours evolving gaseous ammonia. After the reaction was finished, the mixture was cooled to 70 °C, and 1.8 mol of hydrochloric acid solution was added dropwise with stirring. The mixture was stirred for another 40 minutes, then cooled to 15 °C and filtered. The precipitate was dissolved again in absolute ethyl alcohol, filtered, and dried under vacuum at 120 °C to obtain the target product.

Uses and Effects

Semicarbazide hydrochloride has various uses and effects in different fields, such as:

Pharmaceutical: it is used as a raw material for synthesizing nitrofuran antibacterials (such as furazolidone, nitrofurazone, nitrofurantoin) and related compounds, which have antiviral, antiinfective and antineoplastic activities
Chemical analysis: it is used as a reagent for detecting carbonyl compounds as their semicarbazones, which produce crystalline compounds with characteristic melting points. It is also used as a solvent for chromatographic analysis and hormone separation
Heterocyclic synthesis: it is used as a building block for synthesizing various heterocyclic compounds, such as pyrazoles, pyrazolines, pyrazolidines, triazoles, etc.
Other: it is used as a urease substrate and a monoamine oxidase inhibitor¹⁰. It is also used as a pesticide and a photosensitive material

Safety Precautions

Semicarbazide hydrochloride is a hazardous substance that should be handled with care. Some of the safety precautions are:

Wear appropriate protective gloves, clothing, and eye/face protection
Do not eat, drink or smoke when using this product
Avoid breathing dust or fumes
Wash hands and skin thoroughly after handling
Store in a cool, dry and well-ventilated place
Dispose of the waste according to local regulations
Seek medical attention if exposed or in case of any adverse effects