Unit 2, Lessons 08 and 09: Answers to Homework on Substituted Hydrocarbons Page 28, Q 18 – 21 (alkyl halides) Page 26-27, Q 14 – 17 (alcohols) Lesson 08 Page 36, Q 30 – 33 (aldehydes and ketones) Page 40, Q 34 – 37 (carboxylic acids) Lesson 09 Page 32, Q 26a,c, 27a,b, 29 (amines) Page 28 Answers to Homework on Alkyl Halides: 18. Bromoethane: condensed structural formula: CH3 – CH2 – Br I b) 2,3,4-triiodo-3-methylheptane I I CH3 CH3 or: CH3 – CH – C – CH – CH2 – CH2 – CH3 I I I F 19. The molecule is 1,2-difluorocyclohexane. I F 20. CH3 – CH – CH3 2-iodopropane I 21. CH2 – CH2 – CH3 1-iodopropane Page 26-27 Answers to Homework on Alcohols 14. a) b) c) d) e) 1-propanol, a primary alcohol 2-butanol, a secondary alcohol cyclobutanol, a secondary alcohol 2,3-pentanediol, a secondary alcohol 2,4-dimethyl-1-heptanol, a primary alcohol 15a) methanol b) 2-propanol OH CH3 c) 2,2-butanediol OH OH CH3 CH CH3 CH3 C OH CH2 CH3 Page 26-27 Answers to Homework on Alcohols 15d) 3-ethyl-4-methyl-1-octanol CH2 CH2 HO OH CH3 CH CH2 15e) 2,4-dimethyl-1-cyclopentanol CH CH2 CH2 CH2 CH3 CH3 CH3 CH3 16a) the molecule should be named 1,3-pentanediol b) 3,4-diethyl-1-decanol c) 3-methyl-2-pentanol (look for the longest carbon chain) 17. H H C methanol is tetrahedral shaped around the carbon atom, but bent around the oxygen atom O H H Page 36 Answers to Homework on Aldehydes and Ketones 30a) b) c) d) e) butanal 3-octanone 2-methyl-3-hexanone 2-ethyl butanal 4-ethyl-3-methyl-2-heptanone 31a) 2-propyl pentanal CH2 O b) cyclohexanone CH2 CH3 O C CH CH2 CH2 CH3 H d) 4-ethyl-3,5-dimethyloctanal CH2 O C CH2 CH CH CH3 CH CH2 CH2 CH3 H CH3 CH3 32. If the molecular formula is C2H4O, the compound must be an aldehyde because the oxygen will be bonded to a terminal carbon. There are only two carbon atoms in the molecule, so both must be terminal. 33. There are lots of ketones and aldehydes with the molecular formula C6H12O. Some are shown below, but there are many others: O CH2 C 2-methyl pentanal O hexanal CH2 CH2 CH2 C CH3 H CH CH2 CH2 CH3 H CH3 O 3-methyl pentanal CH2 C CH O CH2 4-methyl pentanal CH3 C H CH2 CH2 CH CH3 H CH3 CH3 2-ethyl butanal O O 2,3-dimethyl butanal C CH CH CH3 CH3 C CH3 H O CH3 O C C 2,2-dimethyl butanal CH2 CH CH2 CH2 CH3 CH3 H CH3 C 2-hexanone CH2 CH2 CH2 CH3 CH3 H O CH3 O CH3 CH2 C CH3 CH2 CH2 CH2 O 4-methyl-2-pentanone C CH2 CH CH3 C C CH3 3,3-dimethyl-2-butanone CH3 C 3-methyl-2-pentanone CH CH2 CH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3 O CH 3-hexanone O CH3 C 2-methyl-3-pentanone CH3 Remember when naming: • aldehydes do not need a position number for the R-CHO group, it is always on carbon-1 • the C=O group in ketones always gets the lowest position number, even if it means that the position numbers for other branches are higher Page 40 Answers to Homework on Carboxylic Acids Q 34 – 37 34a) propanoic acid b) 2,2-dimethyl butanoic acid c) 2-ethyl-4,5-dimethyl hexanoic acid 35a) hexanoic acid O O C CH2 CH2 CH2 CH2 CH3 OR OH HO b) 3-propyloctanoic acid O OR O CH2 C CH CH2 CH2 CH2 CH2 CH3 HO OH CH2 CH2 CH3 ethyl group c) 3,4-diethyl-2,3,5-trimethylheptanoic acid CH3 O CH C CH3 CH2 CH C CH3 CH OR CH2 O CH3 HO CH3 CH2 OH CH3 37. Two carboxylic acids with molecular formula C4H8O2 (I think there are only these two): O O C HO CH2 CH2 butanoic acid CH3 C CH HO CH3 CH3 2-methyl-propanoic acid Page 32 Answers to Homework on Amines Q 26a,c, 27a,b, 29 26a) b) c) d) methanamine N-ethyl-2,2-dimethyl-1-propanamine 2-butanamine N,N-dimethylcyclopentanamine 27a) b) 2-pentanamine CH3 CH2 CH2 cyclohexanamine NH2 CH3 CH NH2 c) N-methyl-1-butanamine CH3 NH CH2 CH2 d) N,N-diethyl-3-heptanamine CH2 CH3 CH3 CH2 CH CH3 CH2 N CH2 CH2 28a) b) c) d) CH2 CH2 CH3 CH3 2-pentanamine is a primary amine (the N has only one alkyl group attached) cyclohexanamine is a primary amine (the N has only one alkyl group attached) N-methyl-1-butanamine is a secondary amine (the N has two alkyl groups attached) N,N-diethyl-3-heptanamine is a tertiary amine(the N has three alkyl groups attached) 29. All of the isomers with molecular formula C4H11N. CH3 CH2 CH2 CH2 NH2 1-butanamine CH3 NH CH2 CH3 2-butanamine CH2 CH3 NH CH3 NH2 CH3 CH3 CH CH CH3 N-methyl-1-propanamine CH3 CH2 N N,N-dimethyl ethanamine CH3 CH2 N-methyl-2-propanamine CH3 CH3 CH3 CH2 CH3 CH3 CH2 C NH N-ethyl ethanamine NH2 CH3 2-methyl-2-propanamine