Naming and physical properties of haloalkanes Haloalkanes form an homologous series with a general formula C n H 2n+1 X Where X = Cl, Br or I.

Nomenclature Haloalkanes are named using the same general rules as for other organic compounds. A prefix is used to indicate the halogen present. F = fluoroCl = chloroBr = bromoI = iodo Longest unbranched chain = C3, so this is a propane. Chlorine is on C2 So this is 2 chloro propane

Types of haloalkanes Haloalkanes are classified into primary, secondary and tertiary… … by looking at the number of alkyl groups on the carbon bonded to the halogen.

Primary haloalkanes Primary haloalkanes have ONE alkyl group on the carbon bonded to the halogen. CH 3 CH 2 Cl R

Secondary haloalkanes Secondary have TWO alkyl groups on the carbon bonded to the halogen. R R (CH 3 ) 2 CHCl

Tertiary haloalkanes Tertiary haloalkanes have THREE alkyl groups on the carbon bonded to the halogen. R R R (CH 3 ) 3 CCl

Name the following haloalkanes, stating whether they are primary, secondary or tertiary; CH 3 CH 2 CHClCH 3 CH 3 I (CH 3 ) 2 CHBr CH 3 CHClC(CH 3 ) 3 2 chloro butane (2 o ) Iodomethane (1 o ) 2 bromo propane (2 o ) 2 chloro, 3,3 dimethyl butane (2 o )

Draw out the structures of the following haloalkanes, stating whether they are primary, secondary or tertiary; Tri iodo methane 2 bromo pentane 2 chloro, 2 methyl butane 2 bromo 3 chloro 4 methyl hexane CHI 3 (1 o ) CH 3 CHBr(CH 2 ) 2 CH 3 (2 o ) CH 3 CCl(CH 3 )CH 2 CH 3 (3 o ) CH 3 CHBrCHClC(CH 3 )C 2 H 5 (2 o )

Draw a graph to compare the boiling points ( o C) of alkanes and haloalkanes. X = HX = ClX = BrX = I CH 3 X C2H5XC2H5X C3H7XC3H7X C4H9XC4H9X

BPs of haloalkanes and alkanes Alkanes only have van der Waals forces between molecules. But haloalkanes also have permanent δ/δs.

δ-δ- δ+δ+ δ-δ- δ+δ+ Opposite charges attract, forming a permanent dipole / dipole bond. Intermolecular bonding in haloalkanes

Solubility of haloalkanes Do you think haloalkanes will be more soluble in; A) Polar solvents such as water or B) Non-polar solvents such as cyclohexane?

Solubility of haloalkanes 1) Solubility in water. Organic layer Aqueous layer Despite the polarisation of the halogen/carbon bond haloalkanes are relatively insoluble in water.

2) Solubility in ethanol They are more soluble in ethanol, as they can form van der Waals interactions with the alkyl group. Solubility decreases with chain length

3) Solubility in non- polar solvents. Haloalkanes are readily soluble in non-polar solvents. As they easily mix with hydrocarbons they are used as cleaning agents to remove oily stains.

Solubility of haloalkanes compared. WaterCyclohexane