Kafli 3 - Viðbótardæmi

Viðbótardæmi

3.7 Afbrigði annarra alkana

Sjónræn efnafræði

Identify the functional groups in the following substances, and convert each drawing into a molecular formula (red = O, blue = N).

(a)

A ball and stick model of phenylalanine that includes a benzene ring.

(b)

A ball and stick model of lidocaine that includes an amide group.

Give IUPAC names for the following alkanes, and convert each drawing into a skeletal structure.

(a)

A ball and stick model of 3,3,5-trimethylheptane

(b)

A ball and stick model of 2-methyl-3-ethylpentane

(c)

A ball and stick model of 2,4,4-trimethylpentane

(d)

A ball and stick model of 2-methyl-4-isopropylheptane

Draw a Newman projection along the C2–C3 bond of the following conformation of 2-butanol.

A ball and stick model of 2-butanol is represented. The grey, white and red spheres are carbon, white, and oxygen.

Verkandi hópar

Locate and identify the functional groups in the following molecules.

(a)

A benzene ring with C H 2 O H group on the C 1 and N H C H 3 group on the C 2 carbon is represented.

(b)

A six membered ring with a double bond and a carbonyl group is represented.

(c)

A benzene ring linked to an N H group linked to a C O C H 3 group is represented.

(d)

A C H 3 group linked to a C H connected to an amine group is shown. The C H is connected to a C O O H group.

(e)

Two six membered rings fused together is shown. Both the rings have double bond, carbonyl group and a C H 3 group.

(f)

Two C H 3 groups linked to a triple bond linked to a carbonyl linked to a chlorine group.

Propose structures that meet the following descriptions:

(a) A ketone with five carbons

(b) A four-carbon amide

(c) A five-carbon ester

(d) An aromatic aldehyde

(e) A keto ester

(f) An amino alcohol

Propose structures for the following:

(a) A ketone, C₄H₈O

(b) A nitrile, C₅H₉N

(c) A dialdehyde, C₄H₆O₂

(d) A bromoalkene, C₆H₁₁Br

(e) An alkane, C₆H₁₄

(f) cyclic saturated hydrocarbon, C₆H₁₂

(g) A diene (dialkene), C₅H₈

(h) A keto alkene, C₅H₈O

Predict the hybridization of the carbon atom in each of the following functional groups:

(a) Ketone

(b) Nitrile

(c) Carboxylic acid

Draw the structures of the following molecules:

(a) Biacetyl, C₄H₆O₂, a substance with the aroma of butter; it contains no rings or carbon–carbon multiple bonds.

(b) Ethylenimine, C₂H₅N, a substance used in the synthesis of melamine polymers; it contains no multiple bonds.

(c) Glycerol, C₃H₈O₃, a substance isolated from fat and used in cosmetics; it has an –OH group on each carbon.

Ísómerur

Draw structures that meet the following descriptions (there are many possibilities):

(a) Three isomers with the formula C₈H₁₈

(b) Two isomers with the formula C₄H₈O₂

Draw structures of the nine isomers of C₇H₁₆.

In each of the following sets, which structures represent the same compound and which represent different compounds?

(a)

Three structures with alkane groups are represented. The structure that represent the same compound and different compounds have to be identified.

(b)

Three benzene rings with two O H group as substituents at different rings is shown.

(c)

Three compounds having a six membered ring is represented. There are O H groups as the substituent in these compounds.

Seven constitutional isomers have the formula C₄H₁₀O. Draw as many as you can.

Draw as many compounds as you can that fit the following descriptions:

(a) Alcohols with formula C₄H₁₀O

(b) Amines with formula C₅H₁₃N

(c) Ketones with formula C₅H₁₀O

(d) Aldehydes with formula C₅H₁₀O

(e) Esters with formula C₄H₈O₂

(f) Ethers with formula C₄H₁₀O

Draw compounds that contain the following:

(a) A primary alcohol

(b) A tertiary nitrile

(c) A secondary thiol

(d) Both primary and secondary alcohols

(e) An isopropyl group

(f) A quaternary carbon

Nafngiftir efnasambanda

Draw and name all monobromo derivatives of pentane, C₅H₁₁Br.

Draw and name all monochloro derivatives of 2,5-dimethylhexane, C₈H₁₇Cl.

Draw structures for the following:

(a) 2-Methylheptane

(b) 4-Ethyl-2,2-dimethylhexane

(c) 4-Ethyl-3,4-dimethyloctane

(d) 2,4,4-Trimethylheptane

(e) 3,3-Diethyl-2,5-dimethylnonane

(f) 4-Isopropyl-3-methylheptane

Draw a compound that:

(a) Has only primary and tertiary carbons

(b) Has no secondary or tertiary carbons

(c) Has no secondary or tertiary carbons

Draw a compound that:

(a) Has nine primary hydrogens

(b) Has only primary hydrogens

Give IUPAC names for the following compounds:

(a)

The compound is a five membered ring with a C H 3 group on the second position.

(b)

The given compound is a four membered ring. Two C H 3 groups are present on the third position.

(c)

The given compound is a six membered ring. A C H 3 group is present on C 2 and two C H 3 groups are present on C3.

(d)

The given compound is a seven membered ring with a C H 2 C H 3 on the third position and C H 3 on the sixth position.

(e)

The compound comprises seven carbon with a C H 3 on the C4 carbon and a C H 3 and C H 2 C H 3 on the C6 carbon.

(f)

A six membered ring with two C H 3 groups on C 2 carbon and two C H 3 groups on the C 3 carbon is shown.

Name the five isomers of C₆H₁₄.

Explain why each of the following names is incorrect:

(a) 2,2-Dimethyl-6-ethylheptane

(b) 4-Ethyl-5,5-dimethylpentane

(c) 3-Ethyl-4,4-dimethylhexane

(d) 5,5,6-Trimethyloctane

(e) 2-Isopropyl-4-methylheptane

Propose structures and give IUPAC names for the following:

(a) A diethyldimethylhexane

(b) A (3-methylbutyl)-substituted alkane

Sveigðir

Consider 2-methylbutane (isopentane). Sighting along the C2–C3 bond:

(a) Draw a Newman projection of the most stable conformation.

(b) Draw a Newman projection of the least stable conformation.

(c) If a CH₃ ⟷ CH₃ eclipsing interaction costs 11 kJ/mol (2.5 kcal/mol) and a CH₃ ⟷ CH₃ gauche interaction costs 3.8 kJ/mol (0.9 kcal/mol), make a quantitative plot of energy versus rotation about the C2–C3 bond.

What are the relative energies of the three possible staggered conformations around the C2–C3 bond in 2,3-dimethylbutane? (See Problem 3-42.)

Construct a qualitative potential-energy diagram for rotation about the C–C bond of 1,2-dibromoethane. Which conformation would you expect to be most stable? Label the anti and gauche conformations of 1,2-dibromoethane.

Which conformation of 1,2-dibromoethane (Problem 3-44) would you expect to have the largest dipole moment? The observed dipole moment of 1,2-dibromoethane is μ = 1.0 D. What does this tell you about the actual conformation of the molecule?

Draw the most stable conformation of pentane, using wedges and dashes to represent bonds coming out of the paper and going behind the paper, respectively.

Draw the most stable conformation of 1,4-dichlorobutane, using wedges and dashes to represent bonds coming out of the paper and going behind the paper, respectively.

Almenn dæmi

For each of the following compounds, draw an isomer that has the same functional groups.

(a)

A four membered ring with C H 3 on the C2 and Br group is represented.

(b)

A five membered ring with an O C H 3 group is represented.

(c)

A four membered carbon chain with a cyano group is represented.

(d)

A six membered ring with an O H group is represented.

(e)

A three membered ring with a C H O group is represented.

(f)

A benzene ring with a C H 2 C O O H group is represented.

Malic acid, C₄H₆O₅, has been isolated from apples. Because this compound reacts with 2 molar equivalents of base, it is a dicarboxylic acid.

(a) Draw at least five possible structures.

(b) If malic acid is a secondary alcohol, what is its structure?

Formaldehyde, H₂CO, is known to all biologists because of its usefulness as a tissue preservative. When pure, formaldehyde trimerizes to give trioxane, C₃H₆O₃, which, surprisingly enough, has no carbonyl groups. Only one monobromo derivative (C₃H₅BrO₃) of trioxane is possible. Propose a structure for trioxane.

The barrier to rotation about the C–C bond in bromoethane is 15 kJ/mol (3.6 kcal/mol).

(a) What energy value can you assign to an H ↔ Br eclipsing interaction?

(b) Construct a quantitative diagram of potential energy versus bond rotation for bromoethane.

Increased substitution around a bond leads to increased strain. Take the four substituted butanes listed below, for example. For each compound, sight along the C2–C3 bond and draw Newman projections of the most stable and least stable conformations. Use the data in Table 3.5 to assign strain-energy values to each conformation. Which of the eight conformations is most strained? Which is least strained?

(a) 2-Methylbutane

(b) 2,2-Dimethylbutane

(c) 2,3-Dimethylbutane

(d) 2,2,3-Trimethylbutane

The cholesterol-lowering agents called statins, such as simvastatin (Zocor) and pravastatin (Pravachol), are among the most widely prescribed drugs in the world, with annual sales estimated at approximately $25 billion. Identify the functional groups in both, and tell how the two substances differ.

The chemical structures of simvastatin and pravastatin are represented.

In the next chapter we’ll look at cycloalkanes—saturated cyclic hydrocarbons—and we’ll see that the molecules generally adopt puckered, nonplanar conformations. Cyclohexane, for instance, has a puckered shape like a lounge chair rather than a flat shape. Why?

The chemical structures of non-planar cyclohexane and planar cyclohexane is represented.

We’ll see in the next chapter that there are two isomeric substances, both named 1,2-dimethylcyclohexane. Explain.

The chemical structure of 1,2-dimethylcyclohexane is represented.