Dihalides Geminal dihalide:two halogen atoms are bonded to the same carbon Vicinal dihalide:two halogen atoms are bonded to adjacent carbons. H H HH H-C-C-Br H-C-C-Br H Br Br H ge minal dihalide vicinal dihalide Chapter 6 6
Chapter 6 6 Dihalides • Geminal dihalide: two halogen atoms are bonded to the same carbon • Vicinal dihalide: two halogen atoms are bonded to adjacent carbons. C H H H C H Br Br geminal dihalide C H H Br C H H Br vicinal dihalide =>
IUPAC Nomenclature ·Name as haloalkane. Choose the longest carbon chain,even if the halogen is not bonded to any of those C's. Use lowest possible numbers for position. CH3-CH-CH2CH3 CH2CH2Br C CH3(CH2)2CH(CH2)2CH3 2-chlorobutane 4-(2-bromoe thylhe ptane => Chapter 6 7
Chapter 6 7 IUPAC Nomenclature • Name as haloalkane. • Choose the longest carbon chain, even if the halogen is not bonded to any of those C’s. • Use lowest possible numbers for position. CH3 CH CH2 CH3 Cl CH3 (CH2 ) 2 CH(CH2 ) 2 CH3 CH2 CH2 Br 2-chlorobutane 4-(2-bromoethyl)heptane=>
Systematic Common Names ·Name as alkyl halide. Useful only for small alkyl groups. 。Name these: (CH3)3CBr CH3-CH-CH2CH3 CI CH3 CH3-CH-CH2F > Chapter6 8
Chapter 6 8 Systematic Common Names • Name as alkyl halide. • Useful only for small alkyl groups. • Name these: CH3 CH CH2 CH3 Cl (CH3) 3 CBr CH3 CH CH3 CH2 F =>
"Trivial"Names CH2X2 called methylene halide. 。 CHX3 is a haloform. CX is carbon tetrahalide. 。Examples: >CH2Cl2 is methylene chloride >CHCIa is chloroform >CCl,is carbon tetrachloride. => Chapter6 9
Chapter 6 9 “Trivial” Names • CH2X2 called methylene halide. • CHX3 is a haloform. • CX4 is carbon tetrahalide. • Examples: ➢CH2Cl2 is methylene chloride ➢CHCl3 is chloroform ➢CCl4 is carbon tetrachloride. =>
Uses of Alkyl Halides Solvents -degreasers and dry cleaning fluid Reagents for synthesis of other compounds Anesthetic:Halothane is CF3CHCIBr >CHCI3 used originally (toxic and carcinogenic) Freons,chlorofluorocarbons or CFC's >Freon 12,CF2Cl2,now replaced with Freon 22, CF2CHCI,not as harmful to ozone layer. Pesticides -DDT banned in U.S. => Chapter6 10
Chapter 6 10 Uses of Alkyl Halides • Solvents - degreasers and dry cleaning fluid • Reagents for synthesis of other compounds • Anesthetic: Halothane is CF3CHClBr ➢CHCl3 used originally (toxic and carcinogenic) • Freons, chlorofluorocarbons or CFC’s ➢Freon 12, CF2Cl2 , now replaced with Freon 22, CF2CHCl, not as harmful to ozone layer. • Pesticides - DDT banned in U.S. =>