1,3,4-thiadiazole

1. Basic information

Chinese name: 1,3,4-thiadiazole

English name: 1,3,4-Thiadiazole

Chemical formula: C₂H₂N₂S

Molecular weight: 86.12 g/mol

CAS number: 288-47-1

Structural characteristics: A five-membered heterocyclic compound, containing 1 sulfur atom (S) and 2 nitrogen atoms (N) in the ring, with the nitrogen atoms located at the 1st and 3rd positions and the sulfur atom at the 4th position, forming a conjugated system.

2. Physical and chemical properties

Appearance and state:

At room temperature, it is a colorless to light yellow liquid or crystalline solid with a special smell (similar to the pungent smell of sulfur-containing compounds).

Melting point: 38-40℃ (pure product), boiling point: 143-145℃ (760 mmHg), flash point: about 50℃.

Solubility: Slightly soluble in water (solubility is about 1-5 g/L at 20°C), easily soluble in organic solvents such as ethanol, ether, acetone, chloroform, etc. Chemical properties: The heterocyclic structure is aromatic and highly stable, but it can undergo ring-opening reactions in strong acids, strong bases or at high temperatures. The lone pair of electrons in sulfur and nitrogen atoms makes them nucleophilic, and they can be used as ligands to complex with metal ions or participate in electrophilic substitution reactions (such as halogenation and alkylation). 3. Synthesis method Classical synthesis route: Preparation by cyclization of hydrazide with carbon disulfide or thiourea. For example: Benzoyl hydrazide is condensed with carbon disulfide under alkaline conditions, and oxidative ring closure is used to generate 1,3,4-thiadiazole derivatives. Other methods: Reaction of thiosemicarbazide with carboxylic acid/acyl chloride, or cyclization of 1,2-diamino compounds with sulfiding agents (such as P₂S₅). IV. Application fields

Medicine and pesticides:

As a pharmacophore, it is widely present in antibacterial, antiviral, antitumor and anti-inflammatory drugs. For example:

Some compounds containing 1,3,4-thiadiazole structure can inhibit bacterial cell wall synthesis (such as cephalosporin derivatives).

In pesticides, it is used to prepare insecticides and fungicides (such as thiadiazole derivatives have plant disease resistance induction activity).

Material science:

It is used to synthesize conductive polymers, luminescent materials or metal complex catalysts (due to their coordination ability).

As a corrosion inhibitor, it is used for metal surface treatment (such as steel corrosion protection in acidic media).

Organic synthesis:

As an intermediate to construct complex heterocyclic molecules, or to design functionalized compounds containing sulfur and nitrogen heterocycles.

V. Storage and safety

Storage conditions:

Store in a sealed, cool (≤25℃), dry and ventilated place, away from fire and oxidants.

Liquid products need to be prevented from volatilization, and solid products need to be moisture-proof and avoid oxidation in contact with air.

Safety risks:

Health hazards: May be irritating, inhalation of vapor or contact with skin may cause discomfort, wear protective gloves and goggles.

Explosion risk: Flammable, may burn when exposed to open flame or high temperature, low flash point (need to stay away from fire).

Toxicity data: LD₅₀ (rat, oral) about 500-2000 mg/kg (moderately toxic, please refer to MSDS for specific data).