CHAPTER FOUR Alcohols and Alkyl Halides FIGURE 4. 7 Th Overall reaction: hloride from hol and hydro ( CH3)3COH HCI (CH3)3CCI HOH Step 1: Protonation of tert-butyl alcohol to give an oxonium ion: (CH33C-0: H (CH3)2C=0-H+ rt-Butyl Hydro tert-Butyloxonium Chloride Step 2: Dissociation of tert-butyloxonium ion to give a carbocation (CH3)3C0-H=(CH32C++:0-H H Step 3: Capture of tert-butyl cation by chloride ion: (CH3)3C+ Cl: --( CH3)3C-Cl Chloride ert-Butyl cation chloride account for the consumption of all reactants and the formation of all products, be they organic or inorganic So that we may better understand the chemistry expressed in step 2 and 3. we need to examine carbocations in more detail 4.10 STRUCTURE BONDING, AND STABILITY OF CARBOCATIONS Carbocations are sometimes Carbocations are classified as primary, secondary, or tertiary according to the number of alled carbonium ions or car. carbons that are directly attached to the positively charged carbon. They are named by pending"cation"as a separate word after the IUPAC name of the appropriate alkyl the journal of chemical edu. group. The chain is numbered beginning with the positively charged carbon(the pos cation, pp. 930-933, traces tive charge is always at C of these an ted terms H CH3CH2CH2CH2- CH3 CH,CH2-C CH Pentyl cation 1-Ethylbutyl catio I-Methylcyclohexyl cation (primary carbocation) (secondary carbocation) Common names that have been incorporated into IUPAC nomenclature such as isopropyl sec-butyl, and so on, are permitted. Thus 1, 1-dimethylethyl cation(CH3)3C may be called tert-butyl cation Back Forward Main Menu Study Guide ToC Student OLC MHHE Websiteaccount for the consumption of all reactants and the formation of all products, be they organic or inorganic. So that we may better understand the chemistry expressed in steps 2 and 3, we need to examine carbocations in more detail. 4.10 STRUCTURE, BONDING, AND STABILITY OF CARBOCATIONS Carbocations are classified as primary, secondary, or tertiary according to the number of carbons that are directly attached to the positively charged carbon. They are named by appending “cation” as a separate word after the IUPAC name of the appropriate alkyl group. The chain is numbered beginning with the positively charged carbon (the posi￾tive charge is always at C-1). Common names that have been incorporated into IUPAC nomenclature such as isopropyl, sec-butyl, and so on, are permitted. Thus 1,1-dimethylethyl cation (CH3)3C may be called tert-butyl cation. 1-Methylcyclohexyl cation (tertiary carbocation) CH3 1-Ethylbutyl cation (secondary carbocation) H CH2CH3 CH3CH2CH2 C Pentyl cation (primary carbocation) H H CH3CH2CH2CH2 C 140 CHAPTER FOUR Alcohols and Alkyl Halides (CH3)3C±O  H±Cl BA (CH3)3C±O±H  Cl W H Overall Reaction: tert-Butyl alcohol Hydrogen chloride tert-Butyl chloride Water Step 1: Protonation of tert-butyl alcohol to give an oxonium ion: Step 2: Dissociation of tert-butyloxonium ion to give a carbocation: Step 3: Capture of tert-butyl cation by chloride ion: (CH3)3COH  HCl ±£ (CH3)3CCl  HOH tert-Butyl alcohol tert-Butyl cation Hydrogen chloride tert-Butyloxonium ion Chloride ion W H  tert-Butyl cation Chloride ion tert-Butyl chloride (CH3)3C±O±H BA (CH3)3C  O±H W H W H  tert-Butyloxonium Water ion (CH3)3C  Cl ±£ (CH3)3C±Cl Carbocations are sometimes called carbonium ions or car￾benium ions. An article in the November 1986 issue of the Journal of Chemical Edu￾cation, pp. 930–933, traces the historical development of these and related terms. An electrostatic potential map of tert-butyl cation appears on the first page of this chapter. FIGURE 4.7 The mechanism of formation of tert-butyl chloride from tert-butyl alco￾hol and hydrogen chloride. Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website