DDT- DichloroDiphenylTrichloroethane:

DDT, the abbreviation for dichlorodiphenyltrichloroethane, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochlorine.  DDT use as pesticide and also called “miraculous” by Winston Churchill because of the many lives it saved by killing disease carrying mosquitoes.

DDT was first synthesized in 1874 by the Austrian chemist Othmar Zeidler. DDT's insecticidal action was discovered by the Swiss chemist Paul Hermann Müller in 1939. DDT was used in the second half of World War II to control malaria and typhus among civilians and troops. DDT use is now banned in the United States and many developed countries because it is a nonspecific insecticide that persists in the environment

Reactivity order of Pyrrole, Furan and Thiophene towards Electrophilic substitution :

Pyrrole, furan and thiophene undergo electrophilic substitution reactions like nitration, sulphonation, halogenation etc. characteristic of aromatic rings. That carbons in 5-membered heterocyclic rings have higher electron density compared to benzene and hence undergo electrophilic substitution more readily than benzene.The electrophilic substitution takes place preferentially at 2-position (C-2).

The attack of an electrophile on pyrrole, for example, will lead to formation of 2- and 3-substitution products by way of carbocations (1) and (2) respectively.The substitution occurs preferably at C-2 position because the intermediate obtained by attack at this position is more stable than the intermediate obtained by attack at C-3. The positive charge in intermediate (1) is more delocalized than intermediate (2) and hence is more stable and preferred intermediate.

The electrophilic substitution at C-2 in furan and thiophene can also be accounted in the same manner. Furan is not as reactive as pyrrole in electrophilic substitution reactions because the oxygen in furan is more electronegative than nitrogen in pyrrole and therefore does not enhance the electron density of carbons as much as pyrrole. Thiophene is less reactive than furan towards electrophilic substitution because the p-electrons of sulphur are in 3p orbital which overlaps less effectively than the 2p orbital of nitrogen or oxygen with 2p orbitals of carbon. The relative reactivities towards electrophilic substitution follows the order:

Bredt's rule:

SIR effect:
Dancing Resonance:
Inversion of Amines:

Imidazole is more basic than pyridine? Why?

Imidazole and its derivatives form an interesting and important class of heterocyclic aromatic amines.

The basic strength of imidazole is approximately 100 times more basic than pyridine. Because protonation of imidazole yields an ion that is stabilized by the electron delocalization represented in the resonance structures given as below:

As seen in above figure the electrostatic potential map of the conjugate acid of imidazole (imidazolium ion) is consistent with the resonance description that shows both nitrogens as equivalent.

Related Questions:

Give an explanation for the fact that Guanidine NH=C(CH3)2 is a stronger base than most of amines?

Arrange in correct order of basic Character of aniline, pyrrol, pyridine and piperidine?

What is correct basicity order of pyridine, pyridazine, pyrimidine and pyrazine ?

Why pyridine is more basic than Pyrrole?

Why pyrimidine is less basic than pyridine?

Imidazole is more basic than pyridine? Why?

Biological Important of Imidazole and structure:

Pyridine is almost 1 million times less basic than piperidine? Why?

Cyclohexylamine amine is the stronger base than Aniline? Why?

Tetrahydroquinoline amine is the stronger base than Tetrahydroisoquinoline? Why?