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Published byNikki Georgeson Modified over 9 years ago
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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.
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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
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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.
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Primary haloalkanes Primary haloalkanes have ONE alkyl group on the carbon bonded to the halogen. CH 3 CH 2 Cl R
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Secondary haloalkanes Secondary have TWO alkyl groups on the carbon bonded to the halogen. R R (CH 3 ) 2 CHCl
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Tertiary haloalkanes Tertiary haloalkanes have THREE alkyl groups on the carbon bonded to the halogen. R R R (CH 3 ) 3 CCl
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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 )
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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 )
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Draw a graph to compare the boiling points ( o C) of alkanes and haloalkanes. X = HX = ClX = BrX = I CH 3 X-164-24444 C2H5XC2H5X-88123872 C3H7XC3H7X-424771103 C4H9XC4H9X079102131
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BPs of haloalkanes and alkanes Alkanes only have van der Waals forces between molecules. But haloalkanes also have permanent δ/δs.
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δ-δ- δ+δ+ δ-δ- δ+δ+ Opposite charges attract, forming a permanent dipole / dipole bond. Intermolecular bonding in haloalkanes
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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?
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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.
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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
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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.
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Solubility of haloalkanes compared. WaterCyclohexane
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