ALKANES H ∠CH is the same CHCH CHCH HC HC—CH The IUPAC name is l-butyl-l-methylcyclooctane (g) Number the chain in the direction shown to give 3-ethyl-4, 5, 6-trimethyloctane. When num- bered in the opposite direction, the locants are also 3, 4, 5, and 6. In the case of ties, however, choose the direction that gives the lower number to the substituent that appears first in the name. Ethyl"precedes"methyl"alphabetically 2.20 (a) The alkane contains 13 carbons. Since all alkanes have the molecular formula CH,n+2, the molecular formula must be C,h (b) The longest continuous chain is indicated and numbered as shown CH,CHCH, CH-CHCHCH In alphabetical order, the substituents are ethyl(at C-5), methyl (at C-2), methyl(at C-6).The (c) Fill in the hydrogens in the alkane to identify the various kinds of groups present. There are five methyl( CH,) groups, five methylene( CH,) groups, and three methine( CH) groups in (d) A primary carbon is attached to one other carbon. There are five primary carbons(the carbons of the five CH, groups). A secondary carbon is attached to two other carbons, and there are five of these(the carbons of the five CH, groups). A tertiary carbon is attached to three other carbon is attached to four other carbons. None of the carbons is a quaternary carbonatemary carbons, and there are three of these( the carbons of the three methine groups).A 2.21 (a) The group CH3(CH,)1oCH2-is an unbranched alkyl group with 12 carbons. It is a dodecyl group. The carbon at the point of attachment is directly attached to only one other carbon. It is a primary alkyl group (b) The longest continuous chain from the point of attachment is six carbons; it is a hexyl group bear- ing an ethyl substituent at C-3. The group is a 3-ethylhexyl group. It is a primary alkyl group CH, CH, CHCH,CH,CH3 CHCH (c) By writing the structural formula of this alkyl group in more detail, we see that the longest con- tinuous chain from the point of attachment contains three carbons. It is a 1, 1-diethylpropyl group. Because the carbon at the point of attachment is directly bonded to three other carbons it is a tertiary alkyl group CHCH L2CH3 CH, CH3 Back Forward Main Menu TOC Study Guide Toc Student OLC MHHE Website( f ) The IUPAC name is 1-butyl-1-methylcyclooctane. (g) Number the chain in the direction shown to give 3-ethyl-4,5,6-trimethyloctane. When num￾bered in the opposite direction, the locants are also 3, 4, 5, and 6. In the case of ties, however, choose the direction that gives the lower number to the substituent that appears first in the name. “Ethyl” precedes “methyl” alphabetically. 2.20 (a) The alkane contains 13 carbons. Since all alkanes have the molecular formula CnH2n2, the molecular formula must be C13H28. (b) The longest continuous chain is indicated and numbered as shown. In alphabetical order, the substituents are ethyl (at C-5), methyl (at C-2), methyl (at C-6). The IUPAC name is 5-ethyl-2,6-dimethylnonane. (c) Fill in the hydrogens in the alkane to identify the various kinds of groups present. There are five methyl (CH3) groups, five methylene (CH2) groups, and three methine (CH) groups in the molecule. (d) A primary carbon is attached to one other carbon. There are five primary carbons (the carbons of the five CH3 groups). A secondary carbon is attached to two other carbons, and there are five of these (the carbons of the five CH2 groups). A tertiary carbon is attached to three other carbons, and there are three of these (the carbons of the three methine groups). A quaternary carbon is attached to four other carbons. None of the carbons is a quaternary carbon. 2.21 (a) The group CH3(CH2)10CH2G is an unbranched alkyl group with 12 carbons. It is a dodecyl group. The carbon at the point of attachment is directly attached to only one other carbon. It is a primary alkyl group. (b) The longest continuous chain from the point of attachment is six carbons; it is a hexyl group bear￾ing an ethyl substituent at C-3. The group is a 3-ethylhexyl group. It is a primary alkyl group. (c) By writing the structural formula of this alkyl group in more detail, we see that the longest con￾tinuous chain from the point of attachment contains three carbons. It is a 1,1-diethylpropyl group. Because the carbon at the point of attachment is directly bonded to three other carbons, it is a tertiary alkyl group. CH2CH3 CH2CH3 CCH2CH3 C(CH is rewritten as 2CH3)3 12 3 1 2 34 5 6 CH2CH2CHCH2CH2CH3 CH2CH3 9 7 8 6 5 4 3 2 1 CH3CHCH2CH2CHCHCH3 CH3 CH2CH2CH3 CH2CH3 8 7 5 3 1 6 4 2 H2C H2C H2 C CH2 CH2 C H2C CH3 CH2CH2CH2CH3 is the same as CH2 ALKANES 33 Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website