Presentation on theme: "Degree of Unsaturation"— Presentation transcript:
1 Degree of Unsaturation How to determine the numberof rings and multiple bonds in acompound from its molecular formula
2 No hydrocarbon can contain a greater number of hydrogens than fits the formula CnH2n+2The number of hydrogens is always even.All such compounds are acyclic
3 CH3CH2CH2CH3They may be straight(normal) chains as inn-butane (C4H10)orCH3CH(CH3)CH3they may be branchedas in isobutane (C4H10)
4 on non-adjacent carbons of n-butane (C4H10) are removed If two hydrogen atomson non-adjacent carbonsof n-butane (C4H10)are removedthena ring, cyclobutane(C4H8), is formedwith the loss of H2This process is not necessarily a chemical reactionbut rather a conceptual device.
5 If two hydrogen atomson adjacent carbonsof n-butane (C4H10)are removedthena double bond is formedwith the loss of H2.In this case, the alkene,1-butene (C4H8), is formed.
6 A compound with the molecular formula C4H8 is either an alkene (olefin) or cycloalkane.How to determine the Degree of Unsaturation(DU) of this compound?C4H10- C4H8= H2divided by 2= 1 DUmost saturated C4 compound
7 Try the following formulas: benzeneExample4DUC6H6norborneneC7H103naphthaleneC10H87
8 How is the Degree of Unsaturation of a hydrocarbon containing halogen, or other monovalent atom, determined?Every halogen in a hydrocarbonreplaces a hydrogen.
9 Replace each halogen with hydrogen and then compare this hydrocarbon with the mostsaturated hydrocarbon.The alkyl halide C8H5BrCl2 becomesC8H8C8H18 - C8H8 = H10 /2 = 5 DU
10 One example of an alkyl halide C8H5BrCl2 1 DU - C6HH51 DU - C83 DUC85 DU
11 How is the Degree of Unsaturation of a hydrocarbon containing oxygen, or other divalent atom, determined?