18 CHAPTER 2 IDENTIFY WHICH RESONANCE STRUCTURES BELOW ARE SIGNIFICANT AND WHICH ARE INSIGNIFICANT OOH OOH OOH OOH SkillBuilder 2.9 Identifying Localized and Delocalized Lone Pairs IDENTIFY WHETHER THE LONE PAIR ON THE IDENTIFY THE HYBRIDIZATION STATE NITROGEN ATOM BELOW IS DELOCALIZED OF THE NITROGEN ATOM O O NH2 NH2 Solutions 2.1. H H HH H C H HCH H H H H C HH H H C H H C HCCCOH H C C C O H HCCO H H C H H H H C H CC H C H C H HCH H H H H a) H b) H H c ) H H H H H H H H C H H H H H C H C H C H H H H C C O CCH CC H H CC H C H C H C H H H H H C H C C H H C H d) H H e) H H f) H H H H H H C H H H C C C C OH H H H H H H H H H H H C H H H C C C C CCH H C C C OCH H H g) H h ) H H H H H H i) H H H H H H H C H H C H H H H C H C H HCOH H C H H H H H C HCCOC H H C H H C H H C H H HCCOH H C H H C H H C H j) H H k) H H l ) H H CHAPTER 2 19 (CH ) COCH (CH ) CHOCH CH 2.2 3 3 3 and 3 2 2 3 2.3 Six 2.4 H2C=CHCH3 2.5. H H H H H H C H CC H H C H C H H H H C H HH HH H C H H C C H H C N C H C C C C C H H CCH H H C H HH O HH a) HH b ) c) H H CH3 O HH O H H H3C C CH3 C C C H C C H C C H C C OH C C H H H C C CH H C C H 3 3 HHCC C H H d) CH3 e) H H f) HH OH H O H H C C H H C H H H C C H C H C C C C C C C C H C H H H C H C C C H H H H H g) HH h) H i ) H H H H HH HH O H H C CC O 2 HH C H C C C C H C C C C H2C C CH2 H C HH C C H H H H C C j) HH k) H H l) H2 H2 2.6 a) decrease (7!6) b) no change (8!8) c) no change (8!8) d) increase (5!7) 2.7 a) increase (12!14) b) decrease (8!6) 2.8. OH O OH a) b) c) OH d) 20 CHAPTER 2 OH OH e) f) g) h) O NH2 O i) j) O k) l) Cl m) n) o ) p) O OH O O q) r) 2.9. 2.10. O O Br a) b) δδδ+ c) δδδ+ Cl O O δδδ+ δδδ+ H δδδ+ δδδ+ 2.11. ester amide OO NH2 ether N O N N O amide aromatic HO O H amine H OH O alcohol amine aromatic carboxylic acid 2.12. N N a) b) No charge c) d) No charge CHAPTER 2 21 2.13. O O H a) b) c) No charge d) O H H 2.14. O O O O O OH O O a) b) c) d) e) H O H O O H H O O H H O O O R f) g) h) i) j) 2.15. There are no hydrogen atoms attached to the central carbon atom. The carbon atom has four valence electron. Two valence electrons are being used to form bonds, and the remaining two electrons are a lone pair. This carbon atom is using the appropriate number of valence electrons. 2.16. N N N a) b) H c) d) no lone pairs H NH2 N N N e) f) g) no lone pairs h) 2.17. H O N O CN OON a) b) c) O O O N O CN d) e) NH2 f) 2.18. a) one b) zero c) one d) five 22 CHAPTER 2 2.19 Five lone pairs: O R O NH3 2.20 a) HO O O N O O N N H N H N H S N S S O O O O O O Troglitazone Rosiglitazone Pioglitazone b) Yes, it contains the likely pharmacophore highlighted above. 2.21 a) Violates second rule by giving a fifth bond to a nitrogen atom. b) Does not violate either rule. c) Violates second rule by giving five bonds to a carbon atom. d) Violates second rule by giving three bonds and two lone pairs to an oxygen atom. e) Violates second rule by giving five bonds to a carbon atom. f) Violates second rule by giving five bonds to a carbon atom. g) Violates second rule by giving five bonds to a carbon atom, and violates second rule by breaking a single bond. h) Violates second rule by giving five bonds to a carbon atom, and violates second rule by breaking a single bond. i) Does not violate either rule. j) Does not violate either rule. k) Violates second rule by giving five bonds to a carbon atom. l) Violates second rule by giving five bonds to a carbon atom. 2.22. O 2.23. a) b) CHAPTER 2 23 O O N N O O c) d) OO OO OH OH N N e) f) O O O O N N OO g) h) 2.24. OO OO a) b) O O N N c) b) 2.25. O O O O a) b) O O NH2 NH2 c) d) 24 CHAPTER 2 O O O O O O N N e) f) O O N N O O g) O O H2N OH H2N OH O O h) 2.26. a) b) c) d) CHAPTER 2 25 2.27. NN NN a) b) OO c) 2.28. N N O O a) b) O O c) 2.29. OH OH O O 2.30. O O 26 CHAPTER 2 2.31. HO OH HO OH H2N H2N 2.32. O OO a) b) c) O O O O O O d) OO e) H H H H H O O O O O f) CHAPTER 2 27 NN g) N NN h) NN i) O O O Cl Cl Cl j) 2.33. H H H N N N a) N NN b) NN c) OCN OCN OCN d) 28 CHAPTER 2 O O S S e) f) OO O g) h) OO i) N N C C j) N N N C C C k) OH OH l) CHAPTER 2 29 2.34. O δδδ+ δδδ+ δδδ+ δδδ+ δδδ+ δδδ+ 2.35. δδδ- OH δδδ- δδδ- δδδ- δδδ- 2.36. localized O sp2 hybridized geometry not relevant O N (connected to only one atom) H N H H N delocalized H One of these lone pairs is sp2 hybridized delocalized. The oxygen trigonal planar delocalized localized atom is therefore sp2 sp2 hybridized sp3 hybridized hybridized and has bent trigonal planar trigonal pyramidal geometry. a) b) localized One of these lone pairs is sp2 hybridized delocalized. The oxygen OOH 2 geometry not relevant atom is therefore sp hybridized and has bent (connected to only one atom) H2N NH2 geometry. localized delocalized sp3 hybridized 2 sp hybridized trigonal pyramidal trigonal planar c) localized sp2 hybridized N d) bent delocalized N sp2 hybridized H e) trigonal planar 30 CHAPTER 2 f) localized 2 sp hybridized O geometry not relevant O (connected to only one atom) O localized One of these lone pairs is sp3 hybridized delocalized. The oxygen bent atom is sp2 hybridized and has bent geometry. 2.37. Both lone pairs are localized and, therefore, both are expected to be reactive. 2.38. localized O (not participating in resonance) localized NH (not participating in resonance) N 2 N H delocalized localized (participating in resonance) (not participating in resonance) 2.39. H H H OOH HH H C HH H C N C HH O C H C C C H H C O C C N C C C H H N C C C O C H HO C C C C C O H N H C H O N H H C H H H 2.40. 2.41. 2.42. HO O O HO OH HO OH Vitamin A Vitamin C CHAPTER 2 31 2.43. Twelve (each oxygen atom has two lone pairs) 2.44. O NO N O N 2.45. O OO O O 2.46. a) C4H10 C6H14 C8H18 C12H26 In each of the compounds above, the number of hydrogen atoms is equal to two times the number of carbon atoms, plus two. b) C4H8 C7H14 C7H14 C12H24 In each of the compounds above, the number of hydrogen atoms is two times the number of carbon atoms. 32 CHAPTER 2 c) C6H10 C9H16 C9H16 C7H12 In each of the compounds above, the number of hydrogen atoms is two times the number carbon atoms, minus two.