Draw 1,2,3,4,5,6-hexamethylcyclohexane with all the methyl

The most stable form of the common sugar glucose contains a six-membered ring in the chair conformation with all the substituents equatorial. Draw this most stable conformation of glucose. Equation Transcription: Text Transcription: CH_2OH

Problem 1P Using the general molecular formula for alkanes: (a) Predict the molecular formula of the C28 straight-chain alkane. (b) Predict the molecular formula of 4,6-diethyl-12-(3,5-dimethyloctyl)triacontane, an alkane containing 44 carbon atoms.

Name the following alkanes and haloalkanes. When two or more substituents are present, list them in alphabetical order.

Provide IUPAC names for the following compounds.

Problem 3P Write structures for the following compounds. (a) 3-ethyl-4-methylhexane (b) 3-ethyl-5-isobutyl-3-methylnonane (c) 4-tert-butyl-2-methylheptane (d) 5-isopropyl-3,3,4-trimethyloctane

Problem 5P All of the following names are incorrect or incomplete. In each case, draw the structure (or a possible structure) and name it correctly. (a) 2-methylethylpentane (b) 2-ethyl-3-methylpentane (c) 3-dimethylhexane (d) 4-isobutylheptane (e) 2-bromo-3-ethylbutane (f) 2-diethyl-3-methylhexane

Problem 7P Draw the structures of the following groups, and give their more common names. (a) the (1-methylethyl) group (b) the (2-methylpropyl) group (c) the (1-methylpropyl) group (d) the (1,1-dimethylethyl) group (e) the (3-methylbutyl) group, sometimes called the “isoamyl” group

Problem 6P Give structures and names for: (a) the five isomers of C6H14 (b) the nine isomers of C7H16

Problem 8P Draw the structures of the following compounds. (a) 4-(1,1-dimethylethyl)octane (b) 5-(1,2,2-trimethylpropyl)nonane (c) 3,3-diethyl-4-(2,2-dimethylpropyl)octane

Without looking at the structures, give molecular formulas for the compounds in Problem 3-8 \(\text { (a) and (b) }\). Use the names of the groups to determine the number of carbon atoms, then use the \((2 n+2)\) rule. Equation Transcription: Text Transcription: (a) and (b) (2n+2)

List each set of compounds in order of increasing boiling point. 1. hexane, octane, and decane 2. Octane,\(\left(\mathrm{CH}_{3}\right)_{3}\mathrm{C}-\mathrm{C}\left(\mathrm{CH}_{3}\right)_{3}, \text { and } \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{C}\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}\) Equation Transcription: Text Transcription: (CH_3)_3C-C(CH_3)_3, and CH_3CH_2C(CH_3)_2CH_2CH_2CH_3

Draw a graph, similar to Figure 3-9, of the torsional strain of 2-methylpropane as it rotates about the bond between \(C 1 \text { and } C 2\). Show the dihedral angle and draw a Newman projection for each staggered and eclipsed conformation. Equation Transcription: Text Transcription: C1 and C2

Problem 13P Draw a perspective representation of the most stable conformation of 3-methylhexane.

Draw a graph, similar to Figure 3-11, of the torsional energy of 2-methylbutane as it rotates about the bond.

Give \(\text { IUPAC }\) names for the following compounds. Equation Transcription: Text Transcription: IUPAC CH_3-CH-CH_2CH_3 CH_3 CH_3 CH_3 CH_3

Problem 15P Draw the structure and give the molecular formula for each of the following compounds. (a) 1-ethyl-3-methylcycloheptane (b) isobutylcyclohexane (c) cyclopropylcyclopentane (d) 3-ethyl-1,1-dimethylcyclohexane (e) 3-ethyl-2,4-dimethylhexane (f) 1,1-diethyl-4-(3,3-dimethylbutyl)cyclohexane

Problem 16P Which of the following cycloalkanes are capable of geometric (cis-trans) isomerism? Draw thecis and trans isomers. (a) 3-ethyl-1,1-dimethylcyclohexane (b) 1-ethyl-3-methylcycloheptane (c) 1-ethyl-3-methylcyclopentane (d) 1-cyclopropyl-2-methylcyclohexane

Give \(\text { IUPAC }\) names for the following cycloalkanes. Equation Transcription: Text Transcription: IUPAC CH_3 CH_2CH_2CH_3 CH_2CH_3 C(CH_3)_3 CH_3 H_3C

Problem 18P The heat of combustion of cis-1,2-dimethylcyclopropane is larger than that of the trans isomer.Which isomer is more stable? Use drawings to explain this difference in stability.

Problem 19P trans-1,2-Dimethylcyclobutane is more stable than cis-1,2-dimethylcyclobutane, but cis-1,3-dimethylcyclobutane is more stable than trans-1,3-dimethylcyclobutane. Use drawings to explain these observations.

Problem 20P The cyclohexane chair just drawn has the headrest to the left and the footrest to the right. Draw a cyclohexane chair with its axial and equatorial bonds, having the headrest to the right and the footrest to the left.

Draw 1,2,3,4,5,6-hexamethylcyclohexane with all the methyl groups 1. in axial positions. 2. in equatorial positions. If your cyclohexane rings look awkward or slanted when using the analytical approach just shown, then try the artistic approach:* Draw a wide M, and draw a wide W below it, displaced about half a bond length to one side or the other. Connect the second atoms and the fourth atoms to give the cyclohexane ring with four equatorial bonds. The other two equatorial bonds are drawn parallel to the ring connections. The axial bonds are then drawn vertically.

Draw a Newman projection, similar to Figure 3-25, down the bond in the equatorial conformation of methylcyclohexane. Show that the equatorial methyl group is also anti to \(C 5\). (Using your models will help.) Equation Transcription: Text Transcription: C5

Table 3-6 shows that the axial–equatorial energy difference for methyl, ethyl, and isopropyl groups increases gradually: \(7.6,7.9, \text { and } 8.8 \mathrm{~kJ} / \mathrm{mol}\) (\(1.8,1.9 \text {, and } 2.1 \mathrm{kcal} \mathrm{mol}\)). The tert- butyl group jumps to an energy difference of \(23 \mathrm{~kJ} \mathrm{~mol}\) \(\text { (5.4 kcal mol) }\), over twice the value for the isopropyl group. Draw pictures of the axial conformations of isopropylcyclohexane and tert-butylcyclohexane, and explain why the tert-butyl substituent experiences such a large increase in axial energy over the isopropyl group. Equation Transcription: Text Transcription: 7.6, 7.9, and 8.8 kJ/mol 1.8, 1.9, and 2.1 kcal mol 23 kJ mol (5.4 kcal mol)

Problem 24P Draw the most stable conformation of: (a) ethylcyclohexane (b) 3-isopropyl-1,1-dimethylcyclohexane (c) cis-1-tert-butyl-4-isopropylcyclohexane

Problem 25P (a) Draw both chair conformations of cis-1,4-dimethylcyclohexane, and determine which conformer is more stable. (b) Repeat for the trans isomer. (c) Predict which isomer (cis or trans) is more stable.

Use your results from Problem 3-25 to complete the following table. Each entry shows the positions of two groups arranged as shown. For example, two groups that are trans on adjacent carbons \(\text { (trans-1,2) }\) must be both equatorial \((e, e)\) or both axial \((a, a)\). Equation Transcription: Text Transcription: (trans-1,2) (e,e) (a,a)

Problem 27P Draw the two chair conformations of each of the following substituted cyclohexanes. In each case, label the more stable conformation. (a) cis-1-ethyl-2-methylcyclohexane (b) trans-1,2-diethylcyclohexane (c) cis-1-ethyl-4-isopropylcyclohexane (d) trans-1-ethyl-4-methylcyclohexane

Name the following compounds. Remember that two up bonds are cis; two down bonds are cis; one up bond and one down bond are trans. Equation Transcription: Text Transcription: H_3C CH_3 H_3C CH_3 CH_3 CH_3

Problem 29P Draw the most stable conformation of: (a) cis-1-tert-butyl-3-ethylcyclohexane (b) trans-1-tert-butyl-2-methylcyclohexane (c) trans-1-tert-butyl-3-(1,1-dimethylpropyl)cyclohexane

Name the following compounds.

Use your models to do a chair–chair interconversion on each ring of the conformation of cis- decalin shown in Figure 3-27. Draw the conformation that results.

Problem 32SP (a) There are eighteen isomeric alkanes of molecular formula C8H18. Draw and name any eight of them. (b) Draw and name the six isomeric cyclopentanes of molecular formula C7H14 . These will include four constitutional isomers, of which two show geometric (cis-trans) stereoisomerism.

Which of the following structures represent the same compound? Which ones represent different compounds?

Problem 34SP Draw the structure that corresponds with each name. (a) 3-ethyloctane (b) 4-isopropyldecane (c) sec-butylcycloheptane (d) 2,3-dimethyl-4-propylnonane (e) 2,2,4,4-tetramethylhexane (f) trans-1,3-diethylcyclopentane (g) cis-1-ethyl-4-methylcyclohexane (h) isobutylcyclopentane (i) tert-butylcyclohexane (j) pentylcyclohexane (k) cyclobutylcyclohexane (l) cis-1-bromo-3-chlorocyclohexane

Problem 35SP Each of the following descriptions applies to more than one alkane. In each case, draw and name two structures that match the description. (a) an isopropylheptane (b) a diethyldecane (c) a cis-diethylcyclohexane (d) a trans-dihalocyclopentane (e) a (2,3-dimethylpentyl)cycloalkane (f) a bicyclononane

Problem 36SP Write structures for a homologous series of alcohols (R-OH) having from one to six carbons.

Problem 39SP The following names are all incorrect or incomplete, but they represent real structures. Draw each structure and name it correctly. (a) 2-ethylpentane (b) 3-isopropylhexane (c) 5-chloro-4-methylhexane (d) 2-dimethylbutane (e) 2-cyclohexylbutane (f) 2,3-diethylcyclopentane

Give the IUPAC names of the following alkanes.

In each pair of compounds, which compound has the higher boiling point? Explain your reasoning. (a) octane or 2,2,3-trimethylpentane (b) nonane or 2-methylheptane (c) 2,2,5-trimethylhexane or nonane

Problem 41SP There are eight different five-carbon alkyl groups. (a) Draw them. (b) Give them systematic names. (c) In each case, label the degree of substitution (primary, secondary, or tertiary) of the head carbon atom, bonded to the main chain.

Problem 42SP Use a Newman projection, about the indicated bond, to draw the most stable conformer for each compound. (a) 3-methylpentane about the C2-C3 bond (b) 3,3-dimethylhexane about the C3-C4 bond

Problem 43SP (a) Draw the two chair conformations of cis-1,3-dimethylcyclohexane and label all the positions as axial or equatorial. (b) Label the higher-energy conformation and the lower-energy conformation. (c) The energy difference in these two conformations has been measured to be about 23 kJ (5.4 kcal) per mole. How much of this energy difference is due to the torsional energy of gauche relationships? (d) How much energy is due to the additional steric strain of the 1,3-diaxial interaction?

Problem 44SP Draw the two chair conformations of each compound and label the substituents as axial and equatorial. In each case, determine which conformation is more stable. (a) cis-1-ethyl-2-isopropylcyclohexane (b) trans-1-ethyl-2-isopropylcyclohexane (c) cis-1-ethyl-3-methylcyclohexane (d) trans-1-ethyl-3-methylcyclohexane (e) cis-1-ethyl-4-methylcyclohexane (f) trans-1-ethyl-4-methylcyclohexane

Problem 45SP Using what you know about the conformational energetics of substituted cyclohexanes, predict which of the two decalin isomers is more stable. Explain your reasoning.

Convert each Newman projection to the equivalent line–angle formula, and assign the IUPAC name.

Problem 47SP Draw Newman projections along the C3-C4 bond to show the most stable and least stable conformations of 3-ethyl-2,4,4-trimethylheptane

Problem 48SP Conformational studies on ethane-1,2-diol (HOCH2-CH2OH ) have shown the most stable conformation about the central C-C bond to be the gauche conformation, which is 9.6 kJ/mol (2.3 kcal/mol) more stable than the anti conformation. Draw Newman projections of these conformers and explain this curious result.