HOAÙ HOÏC HÖÕU CÔ

HOAÙ HOÏC HÖÕU CÔ HOAÙ HOÏC HÖÕU CÔHOAÙ HOÏC HÖÕU CÔ Organic ChemistryOrganic Chemistry CHÖÔNG 7 (t t) HYDROCARBON CHÖA NO MAÏCH HỞ ALKYNES AlkynesAlkynes  Alkynes have C C triple bond Alkynes have C[.]

HOÁ HỌC HỮU CƠ Organic Chemistry CHƯƠNG (t.t) HYDROCARBON CHƯA NO MẠCH HỞ ALKYNES Alkynes    Alkynes have C-C triple bond They are more unsaturated than alkenes The general formula is CnH2n-2  The first member of alkyne family is C2H2  IUPAC name : ethyne Common name : acetylene H-C C-H   Characteristics of alkynes       The family name ends in –yne in the IUPAC nomenclature system Geometric isomerism is not possible for alkynes Triple bond is due to the formation of sp-hybridized C The triple bond is composed of one strong sigma bond and two weak pi bonds Chemical reactions are same as alkenes but requires double the reagent as two pi bonds are present in alkynes Acetylene is an important industrial product Acetylene torch used in welding to melt and vaporize steel and iron ALKYNES ALKYNES I Nomenclature of Alkynes “yne”   Step 1: Name longest continuous chain containing the triple bond; parent is “yne” Step 2: Number to give the carbon-carbon triple bond the lowest number CH3 CH3CH2C CCH2CH2CH2CH2CHCH3 9-methyl-3-decyne I Nomenclature of Alkynes “yne”  Step 3: If there is more than one triple bond, indicate by numbers where they are and use prefixes: CH3 CH3C CCH2CH2C CCHCH3 8-methyl-2,6-nonadiyne Nomenclature of Compounds containing both double and triple carbon-carbon bonds: “enyne”    Rule 1: Number from the end to give the multiple bond (double or triple) the lowest number and give each multiple bond a number Rule 2: The parent name is #-alken-#-yne 5-hepten-1-yne 1-hepten-5-yne Nomenclature of Compounds containing both double and triple carbon-carbon bonds: “enyne”  Rule 3: If number is the same the double and the triple bond, give the double bond the lower number 1-hepten-6-yne