HOAÙ HOÏC HÖÕU CÔ

HOAÙ HOÏC HÖÕU CÔ HOAÙ HOÏC HÖÕU CÔHOAÙ HOÏC HÖÕU CÔ Organic ChemistryOrganic Chemistry CHÖÔNG 6 (t t) Alkanes 6 3 TÍNH CHẤT CỦA ALKANES 6 3 1 Phản ứng thế 6 3 2 Phản ứng oxy hóa 6 3 3 Phản ứng đồng p[.]

HOÁ HỌC HỮU CƠ Organic Chemistry CHƯƠNG (t.t) Alkanes 6.3 TÍNH CHẤT CỦA ALKANES 6.3.1 Phản ứng 6.3.2 Phản ứng oxy hóa 6.3.3 Phản ứng đồng phân hóa 6.3.4 PHẢN Ứng CRACKING Oxidation of Alkanes    Combustion Antoine L Lavoisier (1743-1794) was the first to demonstrate the true nature of combustion as an oxidation reaction and to give oxygen its modern name “In all combustion, pure air in which the combustion takes place is destroyed or decomposed and the burning body increases in weight exactly in proportion to the quantity of air destroyed or decomposed” Stoechiometry   from Greek stoikheion element + -metry proportions in which elements are combined in compounds and the quantitative relationships between reactants and products in chemical reactions CH4 + O2 C6H6 + 15/2 O2 CO2 + H2O CO2 + H2O Halogenation reaction  Alkanes undergo substitution reactions with halogens such as fluorine, bromine and chlorine in the presence of heat or light Mechanism of Radical Reactions   The reaction mechanism has three distinct aspects: Chain initiation, chain propagation and chain termination Initiation • Homolytic cleavage Mechanism of Radical Reactions  Initiation and Propagation Mechanism of Radical Reactions  Chain termination • Occasionally the reactive radical intermediates are quenched by reaction pathways that not generate new radicals • The reaction of chlorine with methane requires constant irradiation to replace radicals quenched in chain-terminating steps Mechanism of Radical Reactions   The order of reactivity of methane substitution with halogens is: Fluorine > chlorine > bromine > iodine Monochlorination of alkanes proceeds to give some selectivity Tertiary hydrogens are somewhat more reactive than secondary hydrogens which are more reactive than primary hydrogens Tertiary, secondary and primary hydrogens R R C H R > H R C H R > H R C H H CLO HÓA METAN