(a) Using Newman projections, draw all staggered and eclipsed conformations that result

Three components of the sex pheromone of the female sand bee (Ophrys sphegodes) are saturated hydrocarbons containing 23, 25, and 27 carbon atoms. How many H atoms does each of these alkanes contain? Interestingly, the early spider orchid emits a similar hydrocarbon mixture to attract male sand bees to pollinate its fl owers.

Which of the following is not another representation for isopentane? a. CH3CH2 C CH3 CH3 H c. CH3CH2CH(CH3)2 e. b. CH3 C C CH3 CH3 H H H d. CH3 C C C CH3 H H H H H H f. CH3CH(CH3)CH2CH3

(a) Classify the carbon atoms in each compound as 1, 2, 3, or 4. (b) Classify the hydrogen atoms in each compound as 1, 2, or 3. [1] CH3CH2CH2CH3 [2] (CH3)3CH [3] [4]

Classifying a carbon atom by the number of carbons to which it is bonded can also be done in more complex molecules that contain heteroatoms. Classify each tetrahedral carbon atom in the female sex hormone estrone as 1, 2, 3, or 4. estrone O HO

Draw the five constitutional isomers having molecular formula C6H14.

Draw all constitutional isomers having molecular formula C8H18 that contain seven carbons in the longest chain and a single CH3 group bonded to the chain.

Draw the structure of an alkane with molecular formula C7H16 that contains (a) one 4 carbon; (b) only 1 and 2 carbons; (c) 1, 2, and 3 hydrogens.

Considering compounds AC, which two structures represent the same compound? A CH3(CH2)3CH(CH3)2 B CH3CH2CH(CH3)CH2CH2CH3 C

Draw the five constitutional isomers that have molecular formula C5H10 and contain one ring.

Give the IUPAC name for each compound. a. CH3CH2CH(CH3)CH2CH3 d. f. b. (CH3)3CCH2CH(CH2CH3)2 e. c. CH3(CH2)3CH(CH2CH2CH3)CH(CH3)2

Give the structure corresponding to each IUPAC name. a. 3-methylhexane c. 3,5,5-trimethyloctane e. 3-ethyl-5-isobutylnonane b. 3,3-dimethylpentane d. 3-ethyl-4-methylhexane

Give the IUPAC name for each of the fi ve constitutional isomers of molecular formula C6H14 in Problem 4.5.

Give the IUPAC name for each compound. a. c. e. b. d. f.

Give the structure corresponding to each IUPAC name. a. 1,2-dimethylcyclobutane d. 1-sec-butyl-3-isopropylcyclopentane b. 1,1,2-trimethylcyclopropane e. 1,1,2,3,4-pentamethylcycloheptane c. 4-ethyl-1,2-dimethylcyclohexane

Give the IUPAC names for the fi ve cyclic isomers of molecular formula C5H10 in Problem 4.9.

Arrange the following compounds in order of increasing boiling point. CH3(CH2)6CH3, CH3(CH2)5CH3, CH3CH2CH2CH2CH(CH3)2, (CH3)3CCH(CH3)2

Draw the staggered and eclipsed conformations that result from rotation around the C C bond in CH3 CH2Br.

Draw an energy versus rotation diagram similar to Figure 4.8 for rotation around a C C bond in propane.

a. Draw the three staggered and three eclipsed conformations that result from rotation around the designated bond using Newman projections. b. Label the most stable and least stable conformation.

Consider rotation around the carboncarbon bond in 1,2-dichloroethane (ClCH2CH2Cl). a. Using Newman projections, draw all of the staggered and eclipsed conformations that result from rotation around this bond. b. Graph energy versus dihedral angle for rotation around this bond.

Calculate the destabilization present in each eclipsed conformation. a. H H CH3 CH3 H H b. H H H CH3 CH3 CH3

Classify the ring carbons as up Cs or down Cs. Identify the bonds highlighted in bold as axial or equatorial. HO H Cl HBr OH H H CH3 H H H

Draw a second chair conformation for each cyclohexane. Then decide which conformation is present in higher concentration at equilibrium. a. Br b. Cl c. CH2CH3

When an ethyl group (CH3CH2 ) is bonded to a cyclohexane ring, 96% of the molecules possess an equatorial CH3CH2 group at equilibrium. When an ethynyl group (HC C ) is bonded to a cyclohexane ring, only 67% of the molecules possess an equatorial HC C group at equilibrium. Suggest a reason for this difference.

Draw the structure for each compound using wedges and dashes. a. cis-1,2-dimethylcyclopropane b. trans-1-ethyl-2-methylcyclopentane

For cis-1,3-diethylcyclobutane, draw (a) a stereoisomer; (b) a constitutional isomer.

Label each compound as cis or trans. Then draw the second chair conformation. a. HO HO H H b. H H CI CI c. Br H H Br

Draw a chair conformation of cyclohexane with one CH3CH2 group and one CH3 group that fi ts each description: a. A 1,1-disubstituted cyclohexane with an axial CH3CH2 group b. A cis-1,2-disubstituted cyclohexane with an axial CH3 group c. A trans-1,3-disubstituted cyclohexane with an equatorial CH3 group d. A trans-1,4-disubstituted cyclohexane with an equatorial CH3CH2 group

Classify each transformation as an oxidation, reduction, or neither. a. CH3 C OH O CH3 C H O c. CH3 C CH3 O CH3 C CH3 HO OH b. CH3 C CH3 O CH3CH2CH3 d. O OH

Draw the products of each combustion reaction. a. CH3CH2CH3 flame + O2 b. + O2 flame

Which of the following compounds can be classifi ed as lipids? a. oleic acid CH3(CH2)7CH CH(CH2)7COOH b. H N O NH2 HOOC CH3O O aspartam

Explain why beeswax is insoluble in H2O, slightly soluble in ethanol (CH3CH2OH), and soluble in chloroform (CHCl3).

For each alkane: (a) classify each carbon atom as 1, 2, 3, or 4; (b) classify each hydrogen atom as 1, 2, or 3. [1] [2]

Draw the structure of an alkane that: a. Contains only 1 and 4 carbons. c. Contains only 1 and 2 hydrogens. b. Contains only 2 carbons. d. Contains only 1 and 3 hydrogens

Like ginkgolide B, the cover molecule described in the Prologue, bilobalide is also isolated from Ginkgo biloba extracts. Classify each sp3 hybridized carbon atom in bilobalide as 1, 2, 3, or 4. O O O C(CH3)3 bilobalide O O O OH OH

Draw the structure of all compounds that fi t the following descriptions. a. Five constitutional isomers having the molecular formula C4H8. b. Nine constitutional isomers having the molecular formula C7H16. c. Twelve constitutional isomers having the molecular formula C6H12 and containing one ring.

Give the structure and IUPAC name for each of the nine isomers having molecular formula C9H20 that contains seven carbons in the longest chain and two methyl groups as substituents.

Draw the structure corresponding to each IUPAC name. a. 3-ethyl-2-methylhexane f. 4-butyl-1,1-diethylcyclooctane b. sec-butylcyclopentane g. 6-isopropyl-2,3-dimethylnonane c. 4-isopropyl-2,4,5-trimethylheptane h. 2,2,6,6,7-pentamethyloctane d. cyclobutylcycloheptane i. cis-1-ethyl-3-methylcyclopentane e. 3-ethyl-1,1-dimethylcyclohexane j. trans-1-tert-butyl-4-ethylcyclohexane

Each of the following IUPAC names is incorrect. Explain why it is incorrect and give the correct IUPAC name. a. 2,2-dimethyl-4-ethylheptane e. 1-ethyl-2,6-dimethylcycloheptane b. 5-ethyl-2-methylhexane f. 5,5,6-trimethyloctane c. 2-methyl-2-isopropylheptane g. 3-butyl-2,2-dimethylhexane d. 1,5-dimethylcyclohexane h. 1,3-dimethylbutane

Give the IUPAC name for each compound. a. CH2CH2CH3 H CH3 CH3 CH2CH2CH3 H b. CH2CH3 H CH3 H CH2CH3 CH3 c. CH2CH2CH3 H CH3 CH3CH2CH2 CH2CH3 CH3CH2

Rank each group of alkanes in order of increasing boiling point. Explain your choice of order. a. CH3CH2CH2CH2CH3, CH3CH2CH2CH3, CH3CH2CH3 b. CH3CH2CH2CH(CH3)2, CH3(CH2)4CH3, (CH3)2CHCH(CH3)2

The melting points and boiling points of two isomeric alkanes are as follows: CH3(CH2)6CH3, mp = 57 C and bp = 126 C; (CH3)3CC(CH3)3, mp = 102 C and bp = 106 C. (a) Explain why one isomer has a lower melting point but higher boiling point. (b) Explain why there is a small difference in the boiling points of the two compounds, but a huge difference in their melting points.

Which conformation in each pair is higher in energy? Calculate the energy difference between the two conformations using the values given in Table 4.3. CH3 H CH3 CH3 H H H H CH3 CH3 H CH3 or H H H CH3 CH3 CH3 H H CH3 CH3 H CH3

Considering rotation around the indicated bond in each compound, draw Newman projections for the most stable and least stable conformations. a. CH3 CH2CH2CH2CH3 b. CH3CH2CH2 CH2CH2CH3

Convert each three-dimensional model to a Newman projection around the indicated bond. a. b. c.

(a) Using Newman projections, draw all staggered and eclipsed conformations that result from rotation around the indicated bond in each molecule; (b) draw a graph of energy versus dihedral angle for rotation around this bond. CH3CH2 [1] CH2CH2CH3 CH3CH2 CHCH2CH3 CH3 [2]

Label the sites of torsional and steric strain in each conformation. a. H H CH3 CH3 H CH3 b. H H CH3 H CH3 CH3 c. H CH2CH3 H H H CH3CH2

Calculate the barrier to rotation for each designated bond. a. CH3 CH(CH3)2 b. CH3 C(CH3)3

The eclipsed conformation of CH3CH2Cl is 15 kJ/mol less stable than the staggered conformation. How much is the H,Cl eclipsing interaction worth in destabilization?

(a) Draw the anti and gauche conformations for ethylene glycol (HOCH2CH2OH). (b) Ethylene glycol is unusual in that the gauche conformation is more stable than the anti conformation. Offer an explanation.

For each compound drawn below: a. Label each OH, Br, and CH3 group as axial or equatorial. b. Classify each conformation as cis or trans. c. Translate each structure into a representation with a hexagon for the six-membered ring, and wedges and dashes for groups above and below the ring. d. Draw the second possible chair conformation for each compound. H HO H OH Br CH3 H H HO H OH H [1] [2] [3]

Draw the two possible chair conformations for cis-1,3-dimethylcyclohexane. Which conformation, if either, is more stable?

For each disubstituted cyclohexane, indicate the axial/equatorial position of the substituents in the following table. The fi rst entry has been completed for you. Axial/equatorial substituent location Disubstituted cyclohexane Conformation 1 Conformation 2 a. 1,2-cis disubstituted Axial/equatorial Equatorial/axial b. 1,2-trans disubstituted c. 1,3-cis disubstituted d. 1,3-trans disubstituted e. 1,4-cis disubstituted f. 1,4-trans disubstituted

For each compound drawn below: a. Draw representations for the cis and trans isomers using a hexagon for the six-membered ring, and wedges and dashes for substituents. b. Draw the two possible chair conformations for the cis isomer. Which conformation, if either, is more stable? c. Draw the two possible chair conformations for the trans isomer. Which conformation, if either, is more stable? d. Which isomer, cis or trans, is more stable and why? [1] [2] [3]

Which of the given 1,3,5-trimethylcyclohexane isomers is more stable? Explain your choice. CH3 CH3 CH3 CH3 or CH3 CH3

Convert each of the following structures into its more stable chair form. One structure represents menthol and one represents isomenthol. Menthol, the more stable isomer, is used in lip balms and mouthwash. Which structure corresponds to menthol? OH OH

Glucose is a simple sugar with fi ve substituents bonded to a six-membered ring. O HO HO OH OH HO glucose a. Using a chair representation, draw the most stable arrangement of these substituents on the sixmembered ring. b. Convert this representation into one that uses a hexagon with wedges and dashes.

Galactose is a simple sugar formed when lactose, a carbohydrate in milk, is hydrolyzed. Individuals with galactosemia, a rare inherited disorder, lack an enzyme needed to metabolize galactose, and must avoid cows milk and all products derived from cows milk. Galactose is a stereoisomer of glucose (Problem 4.63). O galactose OH OH HO HO HO a. Draw both chair forms of galactose and label the more stable conformation. b. Which simple sugar, galactose or glucose, is more stable? Explain. c. Draw a constitutional isomer of galactose. d. Draw a stereoisomer of galactose that is different from glucose.

Classify each pair of compounds as constitutional isomers, stereoisomers, identical molecules, or not isomers of each other.

Classify each pair of compounds as constitutional isomers or identical molecules. a. H CH2CH3 CH H CH3 H CH3 CH3 H CH3 CH3 H CH2CH3 CH3CH2 and b. and H CH3 CH3 H CH(CH3)2 CH3

Draw a constitutional isomer and a stereoisomer for each compound. a. b. H HO H OH c. Cl Cl

Draw the three constitutional isomers having molecular formula C7H14 that contain a fi ve-membered ring and two methyl groups as substituents. For each constitutional isomer that can have cis and trans isomers, draw the two stereoisomers.

Classify each reaction as oxidation, reduction, or neither. a. CH3CHO CH3CH2OH d. CH2 CH2 H C C H b. O e. CH3 CH2Br c. CH2 CH2 HOCH2CH2OH f. CH3CH2OH CH2 CH2

Hydrocarbons like benzene are metabolized in the body to arene oxides, which rearrange to form phenols. This is an example of a general process in the body, in which an unwanted compound (benzene) is converted to a more water-soluble derivative called a metabolite, so that it can be excreted more readily from the body. O OH benzene arene oxide phenol a. Classify each of these reactions as oxidation, reduction, or neither. b. Explain why phenol is more water soluble than benzene. This means that phenol dissolves in urine, which is largely water, to a greater extent than benzene.

Which of the following compounds are lipids? a. HO OH O OH mevalonic acid c. HO OH estradiol d. sucrose O O O HO HO HO OH OH OH HO HO b. squalene

Cholic acid, a compound called a bile acid, is converted to a bile salt in the body. Bile salts have properties similar to soaps, and they help transport lipids through aqueous solutions. Explain why this is so. HO OH OH COH O HO OH OH CNHCH2CH2SO3 Na+ O cholic acid a bile acid bile salt

Mineral oil, a mixture of high molecular weight alkanes, is sometimes used as a laxative. Why are individuals who use mineral oil for this purpose advised to avoid taking it at the same time they consume foods rich in fat-soluble vitamins such as vitamin A?

Although penicillin G has two amide functional groups, one is much more reactive than the other. Which amide is more reactive and why? N S O CH3 CH3 H N O COOH penicillin G

Haloethanes (CH3CH2X, X = Cl, Br, I) have similar barriers to rotation (13.415.5 kJ/mol) despite the fact that the size of the halogen increases, Cl Br I. Offer an explanation.

When two six-membered rings share a C C bond, this bicyclic system is called a decalin. There are two possible arrangements: trans-decalin having two hydrogen atoms at the ring fusion on opposite sides of the rings, and cis-decalin having the two hydrogens at the ring fusion on the same side. H H H decalin trans-decalin cis-decalin H a. Draw trans- and cis-decalin using the chair form for the cyclohexane rings. b. The trans isomer is more stable. Explain why.

Read Appendix B on naming branched alkyl substituents, and draw all possible alkyl groups having the formula C5H11 . Give the IUPAC names for the eight compounds of molecular formula C10H20 that contain a cyclopentane ring with each of these alkyl groups as a substituent.