The most characteristic reactions of benzenoid arenes are the substitution reactions that occur when they react with electrophilic reagents. The electrophiles are either a positive ion (E+) or some other electron-deficient species with a large partial positive charge
A ring that contains at least one heteroatom (an atom other than carbon) is called a heterocycle, and a substance based on a heterocyclic ring is a heterocyclic compound. Heterocyclic compounds containing N, O or S are by far the most common
Compounds were classified as being either aliphatic or aromatic in the latter part of the nineteenth century. To be classified as aliphatic meant then that the chemical behavior of a compound was “fatlike”. To be classified as aromatic meant then that the compound had a low hydrogen/carbon ratio and that it was “fragrant
A UV-Vis spectrophotometer measures the amount of light absorbed at each wavelength of the UV and visible regions of the electromagnetic spectrum. λmax— the wavelength of maximum absorption
A hydrocarbon whose molecules contain two double bonds is called an alkadiene(alkatriene for three double bonds); A hydrocarbon with two triple bonds is called an alkadiyne; A hydrocarbon with a double and triple bond is called an alkenyne
Conjugated unsaturated systems have a p orbital on a carbon adjacent to a double bond The p orbital can come from another double or triple bond The p orbital may be the empty p orbital of a carbocation or a p orbital with a single electron in it (a radical)
The reactivity of organometallic compounds increases with the percent ionic character of the carbon-metal bond. RLi and RMgX are of great importance in organic synthesis
