1,3,4-Thiadiazole химические свойства, назначение, производство
Описание
1,3,4-Thiadiazole is a five-membered, aromatic, weakly basic, planer, electron-deficient, conjugated heterocyclic ring system comprised of two carbon atoms, one sulfur atom, and two pyridine-like nitrogen atoms present at the 3- and 4-positions of the ring. The dipole moment (3.25 D) for 1,3,4-thiadiazole suggests that it is a polar symmetric molecule with pseudo-aromatic character. The carbon atoms at the 2- and 5-positions are electron deficient because of the inductive effect of nitrogen and sulfur and thus they are inert toward electrophilic substitution but reactive toward nucleophilic attack.
Использование
1,3,4-Thiadiazole, a bioisostere of the thiazole ring, has been used in the synthesis of cephalosporine and cefazedone, which are used as antibiotics. Megazole is another 1,3,4-thiadiazole-based drug, widely used in the treatment of African trypanosomes, also known as sleeping sickness. Azetepa, a phosphoruscontaining drug, has been used for the treatment of cancer. Tebtheuron is known as a broad-spectrum herbicide and is used to control a variety of weeds and herbaceous and woody plants. Numerous thiadiazole derivatives are patented as bactericides, insecticides, and fungicides.
Химическая реактивность
Atomic charges have been calculated by the DFT method. The maximum charge was found at the S atom (0.818) and thus it is the favorite position for soft nucleophilic attack. The atomic charge on each carbon is ?0.3275. Because of the presence of the two pyridine-like nitrogen atoms in the ring, which make the C2 - and C5 -positions electronically poor, nucleophilic substitution of the leaving groups present at either the C2 - or C5 -position becomes highly facile. However, the atomic charge on N3 and N4 (?0.0308) makes them preferential sites for electrophilic attack and readily N-alkylated or N-acylated. In strongly basic conditions the thiadiazole ring leads to ring fission.
1,3,4-Thiadiazole препаратная продукция и сырье
сырьё
препарат