✅18 - Organic Chemistry III

Compounds containing a hydrocarbon ring containing delocalised electrons

Ones which do not have a hydrocarbon ring with delocatised electrons

An arene

A colourless liquid Boiling temperature of 80 degrees Insoluble in water

C6H6

Alternating double and single bonds in a cyclic structure with a ring of hydrogen around it

If benzene contained three C=C bonds, it would readily decolourise bromine water, but it does not, suggesting there are no double bonds

If the Kekule structure is correct, there would be four isomers of dibromobenzene, however only three are known to exist as there are no C=C bonds

C-C bonds and C=C bonds are different lengths, but in benzene the bonds lengths are all the same, so there cannot be different types of bonds in the molecule

The actual enthalpy change of hydrogenation of benzene differs from the theoretical value for if it had C=C double bonds

Bromine water Isomers of dibromobenzene Bond lengths Enthalpy change of hydrogenation

In two delocalised rings, one above and one above the Carbon ring, of pi electrons

Hydrogen, and heating under pressure with a nickel catalyst

C6H6 + 3H2 ——> C6H12

A smoky flame

Usually metal-halogen compounds such as aluminium chloride

Bromobenzene and hydrogen bromide

The substitution of a hydrogen atom by a nitro group, NO2

Warming it with a mixture of conc nitric acid and sulfuric acid catalyst

Nitrobenzene and water

Alkylation and acylation

Using reagent XY, one of the hydrogens In benzene is substituted by Y, and the other product is HX A catalyst is needed Anyhydrous conditions are needed because water would react with catalyst and organic product

CH3

COCH3