Chapter 23

In carbon compounds, the carbon atom can achieve an octet configuration in several ways. Draw the Lewis structure of a hydrocarbon compound in which: (a) Carbon is bonded via four single bonds to adjacent atoms. (b) Carbon is bonded via two single bonds and one pi bond; (c) Carbon is bonded via one single bond and one triple bond; (d) Carbon is bonded via two double bonds.

Identify the hybridization and the bond angles for the following: (a) Carbon bonded via four single bonds to adjacent atoms. (b) Carbon bonded to adjacent atoms via two single bonds and one pi bond; (c) Carbon bonded to adjacent atoms via one single bond and one triple bond; (d) Carbon bonded to adjacent atoms via two double bonds.

Is violet light (with a wavelength of \(400 \mathrm{nm}\) ) sufficiently energetic to break a carbon-carbon single bond (the average C-C bond energy is \(346 \mathrm{kJ} / \mathrm{mol}\) )?

Ethene, \(\mathrm{C}_{2} \mathrm{H}_{4},\) is unstable with respect to decomposition to the elements \(\left(\Delta_{f} H^{\circ}=52.47 \mathrm{kJ} / \mathrm{mol}\right) .\) It is also unstable with respect to polymerization to polyethylene. Nevertheless, samples of ethane can be stored without decomposition essentially forever. Why is this so?

Compounds with the same elemental composition but a different arrangement of atoms are called: (a) stereoisomers, (b) structural isomers, (c) geometric isomers, (d) optical isomers.

Compounds with the same attachment of atoms but different orientation in space are called: (a) stereoisomers, (b) structural isomers, (c) cis-trans isomers, (d) optical isomers.

Determine how many structural isomers and geometric isomers are possible for compounds having the formula \(\mathrm{C}_{4} \mathrm{H}_{10}\). Are any of the possible isomers chiral?

Determine how many non-cyclic structural isomers and geometric isomers are possible for compounds having the formula \(\mathrm{C}_{4} \mathrm{H}_{8} .\) Are any of the possible isomers chiral?

What is the name of the straight (unbranched) chain alkane with the formula \(\mathrm{C}_{7} \mathrm{H}_{16} ?\)

What is the molecular formula for an alkane with 12 carbon atoms?

Which of the following compounds can be an alkane? (a) \(\mathrm{C}_{2} \mathrm{H}_{4}\) (b) \(\mathrm{C}_{5} \mathrm{H}_{12}\) (c) \(\mathrm{C}_{14} \mathrm{H}_{30}\) (d) \(\mathrm{C}_{7} \mathrm{H}_{8}\)

Which of the following compounds can be a cyclo alkane? (a) \(\mathrm{C}_{3} \mathrm{H}_{5}\) (b) \(\mathrm{C}_{5} \mathrm{H}_{10}\) (c) \(\mathrm{C}_{14} \mathrm{H}_{30}\) (d) \(\mathrm{C}_{8} \mathrm{H}_{8}\)

One of the structural isomers with the formula \(\mathrm{C}_{3} \mathrm{H}_{20}\) has the name 3 -ethyl- 2 -methylhexane. Draw its structure. Draw and name another structural isomer of \(\mathrm{C}_{9} \mathrm{H}_{20}\) in which there is a fivecarbon chain.

Isooctane, 2,2,4 -trimethylpentane, is one of the possible structural isomers with the formula \(\mathrm{C}_{8} \mathrm{H}_{18} .\) Draw the structure of this isomer, and draw and name structures of two other isomers of \(\mathrm{C}_{8} \mathrm{H}_{18}\) in which the longest carbon chain is five atoms.

Draw the structure of each of the following compounds: (a) 2,3 -dimethylhexane (b) 2,3 -dimethyloctane (c) 3 -ethylheptane (d) 3-ethyl-2-methylhexane

Draw structures for the following compounds. (a) 3 -ethylpentane (b) 2,3 -dimethylpentane (c) 2,4 -dimethylpentane (d) 2,2 -dimethylpentane

Draw Lewis structures and name all possible alkanes that have a seven-carbon chain with one methyl substituent group. Which of these isomers has a chiral carbon center?

Four (of six possible) dimethylhexanes are named below. Draw the structures of each, and determine which of these isomers has a chiral carbon center. (a) 2,2 -dimethylhexane (b) 2,3 -dimethylhexane (c) 2,4 -dimethylhexane (d) 2,5 -dimethylhexane

Draw the structure of the chair form of cyclohexane. Identify the axial and equatorial hydrogen atoms in this drawing.

Draw a structure for cycloheptane. Is the sevenmember ring planar? Explain your answer.

There are two ethylheptanes (compounds with a seven-carbon chain and one ethyl substituent). Draw the structures, and name these compounds. Is either isomer chiral?

Among the 18 structural isomers with the formula \(\mathrm{C}_{8} \mathrm{H}_{18}\) are two with a five-carbon chain having one ethyl and one methyl substituent group. Draw their structures, and name these two isomers.

List several typical physical properties of \(\mathrm{C}_{4} \mathrm{H}_{10}\) Predict the following physical properties of dodecane, \(\mathrm{C}_{12} \mathrm{H}_{26}:\) color, state \((\mathrm{s}, \ell, \mathrm{g}),\) solubility in water, solubility in a nonpolar solvent.

Write balanced equations for the following reactions of alkanes. (a) The reaction of methane with excess chlorine. (b) Complete combustion of cyclohexane, \(\mathrm{C}_{6} \mathrm{H}_{12}\) with excess oxygen.

Draw structures for the cis and trans isomers of 4 -methyl-2-hexene.

What structural requirement is necessary for an alkene to have cis and trans isomers? Can cis and trans isomers exist for an alkane? For an alkyne?

A hydrocarbon with the formula \(\mathrm{C}_{5} \mathrm{H}_{10}\) can be either an alkene or a cycloalkane. (a) Draw a structure for each of the six isomers possible for \(\mathrm{C}_{5} \mathrm{H}_{10},\) assuming it is an alkene. Give the systematic name of each isomer. (b) Draw a structure for a cycloalkane having the formula \(\mathrm{C}_{5} \mathrm{H}_{10}\)

Five alkenes have the formula \(\mathrm{C}_{7} \mathrm{H}_{14}\) and a sevencarbon chain. Draw their structures and name them.

Draw the structure and give the systematic name for the products of the following reactions: (a) \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2}+\mathrm{Br}_{2} \rightarrow\) (b) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}=\mathrm{CHCH}_{3}+\mathrm{H}_{2} \rightarrow\)

The compound 2,3 -dibromo- 2 -methylhexane is formed by addition of \(\mathrm{Br}_{2}\) to an alkene. Identify the alkene, and write an equation for this reaction.

Draw structures for the four alkenes that have the formula \(\mathrm{C}_{3} \mathrm{H}_{5} \mathrm{Cl},\) and name each compound. (These are derivatives of propene in which a chlorine atom replaces one hydrogen atom.)

There are seven possible dichloropropene isomers (molecular formula \(\mathrm{C}_{3} \mathrm{H}_{4} \mathrm{Cl}_{2}\) ). Draw their structures and name each isomer. (Hint: Don't overlook cis-trans isomers.)

Hydrogenation is an important chemical reaction of compounds that contain double bonds. Write a chemical equation for the hydrogenation of 1-hexene. Hydrogenation reactions are used extensively in the food industry. Describe this reaction and explain its use and importance.

Elemental analysis of a colorless liquid has given its formula as \(\mathrm{C}_{5} \mathrm{H}_{10}\). You recognize that this could be either a cycloalkane or an alkene. A chemical test to determine the class to which this compound belongs involves adding bromine. Explain how this would allow you to distinguish between the two classes.

Draw structural formulas for the following compounds: (a) 1,3 -dichlorobenzene (alternatively called \(m\) -dichlorobenzene) (b) 1-bromo-4-methylbenzene (alternatively called \(p\) -bromotoluene)

Write an equation for the preparation of hexylbenzene from benzene and other appropriate reagents.

Aromatic compounds react with a mixture of nitric and sulfuric acid to form aromatic compounds containing a nitro \(\left(-\mathrm{NO}_{2}\right)\) group. Two isomeric compounds are formed by nitration of 1,2 -dimethylbenzene. Draw the structures and name these compounds.

Nitration of toluene gives a mixture of two products, one with the nitro group \(\left(-\mathrm{NO}_{2}\right)\) in the ortho position and one with the nitro group in the para position. Draw structures of the two products.

Draw structural formulas for the following alcohols, and tell if each is primary, secondary, or tertiary: (a) \(1-\) butanol (b) 2-butanol (c) 3,3 -dimethyl- 2 -butanol (d) 3,3 -dimethyl- 1 -butanol

Write the formula, and draw the structure, for each of the following amines: (a) ethylamine (b) dipropylamine (c) butyldimethylamine (d) triethylamine

Name the following amines: (a) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}\) (b) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{N}\) (c) \(\left(\mathrm{CH}_{3}\right)\left(\mathrm{C}_{2} \mathrm{H}_{5}\right) \mathrm{NH}\) (d) \(\mathrm{C}_{6} \mathrm{H}_{13} \mathrm{NH}_{2}\)

Draw structural formulas for the four possible alcohols with the formula \(\mathrm{C}_{4} \mathrm{H}_{10}\) O. Give the systematic name of each.

Draw structures of the product formed by oxidation of the following alcohols. Assume an excess of oxidizing agent is used in each case. (a) 2 -methyl-1-pentanol (b) 3-methyl-2-pentanol (c) \(\mathrm{HOCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}\) (d) \(\mathrm{H}_{2} \mathrm{NCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}\)

Aldehydes and carboxylic acids are formed by oxidation of primary alcohols, and ketones are formed when secondary alcohols are oxidized. Give the name and formula for the alcohol that, when oxidized, gives the following products: (a) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CHO}\) (b) 2-hexanone

Draw structural formulas for (a) 2 -pentanone,(b) hexanal, and (c) pentanoic acid.

Draw structural formulas for the following acids and esters: (a) 2 -methylhexanoic acid (b) pentyl butanoate (which has the odor of apricots (c) octyl acetate (which has the odor of oranges)

Give the structural formula and systematic name for the organic product, if any, from each of the following reactions: (a) pentanal and \(\mathrm{KMnO}_{4}\) (b) 2-octanone and LiAlH \(_{4}\)

Give the structural formula and name for the organic product from the following reactions. (a) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CHO}+\mathrm{LiAlH}_{4}\) (b) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}+\mathrm{KMnO}_{4}\)

Describe how to prepare propyl propanoate beginning with 1-propanol as the only carboncontaining reagent.

What is the structure of the product from the reaction of butanoic acid and methylamine? To what class of compounds does this belong? Write a balanced chemical equation for the reaction.