organic chemistry.....aim 2

what are homologous series of hydrocarbons?

.....aim 1

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aim 3.....

 

MU #1 Organic compounds can be named using the IUPAC system.

Example

See table P and table Q to write the first ten  molecular, condensed structural formulas, and structural formula for alkanes, alkenes, and alkynes.

 

Alkanes  CnH2n+2

Name

Molecular formula

Condensed structural formula

methane

CH4

CH4

ethane

C2H6

CH3CH3

propane

C3H8

CH3CH2CH3

etc...

 

 

 

Alkenes  CnH2n

Name

Molecular formula

Condensed structural formula

methene

 

 

ethene

C2H4

CH2CH2

propene

C3H6

CH2CHCH3

1-butene

C4H8

CH2CHCH2CH3                  (double bond starts at the first carbon)

2-butene

C4H8

CH3CHCHCH3                    (double bond starts at the second carbon)

1-pentene

C5H10

CH2CHCH2CH2CH3           (double bond starts at the first carbon)

2-pentene

C5H10

CH3CHCH2CH2CH3           (double bond starts at the second carbon)

etc...

 

 

 

Alkynes  CnH2n-2

Name

Molecular formula

Condensed structural formula

methyne

 

 

ethyne

C2H2

CHCH

propyne

C3H4

CHCCH3

1-butyne

C4H6

CHCCH2CH3                       (triple bond starts at the first carbon)

2-butyne

C4H6

CH3CCCH3                          (triple bond starts at the second carbon)

1-pentyne

C5H8

CHCCH2CH2CH3                (triple bond starts at the first carbon)

2-pentyne

C5H8

CH3CCCH2CH3                   (triple bond starts at the second carbon)

etc...

 

 

 

Alkyl radical

An alkyl radical has the name of the corresponding alkane but ends in -yl instead than -ane. One H is removed from an alkane so that an alkyl can attached to another hydrocarbon chain.

Example

 

 

H

 

 

 

 

 

 

 

H

 

 

 

 

 

 

 

 

|

 

 

 

 

 

 

 

|

 

 

 

 

 

 

H

—

C

—

H

 

 

 

H

—

C

·

<---lone electron

 

 

|

 

 

 

 

 

 

 

|

 

 

 

 

 

 

 

 

H

 

 

 

 

 

 

 

H

 

 

 

 

 

 

methane (CH4)

 

 

methyl radical (CH3)

 

 

 

 

Example

 

 

H

 

H

 

 

 

 

 

 

 

H

 

H

 

 

 

 

 

 

 

 

|

 

|

 

 

 

 

 

 

 

|

 

|

 

 

 

 

 

 

H

—

C

—

C

—

H

 

 

 

H

—

C

—

C

·

<---lone electron

 

 

|

 

|

 

 

 

 

 

 

 

|

 

|

 

 

 

 

 

 

 

 

H

 

H

 

 

 

 

 

 

 

H

 

H

 

 

 

 

 

 

ethane (C2H6)

 

 

 

 

 

ethyl radical (C2H5)

 

 

Rules for naming organic compounds 

1. Find the longest chain of carbon.

2. Number the chain of carbon so that the side chain, if any, is located at the lowest carbon number.

3. If the same group occurs more than once as a side chain, use di-, tri-, and tetra-

4. If more than one side chains are present, arrange them by alphabetical order to form the name (prefixes are not considered).

Example

 

 

 

 

 

 

H

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

|

 

 

 

 

 

3,5-dimethyldecane

 

 

 

 

 

H

—

C

—

H

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

|

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

H

 

H

 

 

H

 

H

 

H

 

H

 

H

 

H

 

H

 

 

 

 

 

|

 

|

 

 

|

 

|

 

|

 

|

 

|

 

|

 

|

 

 

 

H

—

C

—

C

—

C

—

C

—

C

—

C

—

C

—

C

—

C

—

C

—

H

 

 

 

|

 

|

 

|

 

|

 

|

 

|

 

|

 

|

 

|

 

|

 

 

 

 

 

H

 

H

 

H

 

H

 

 

H

 

H

 

H

 

H

 

H

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

H

—

C

—

H

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

|

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

H

 

 

 

 

 

 

 

 

 

Problems

Draw the structural formula of the following alkanes:

    2-methylbutane

    2,3-dimethylpentane

    3-ethyl-2,5-dimethylhexane

    2-methyl-4-propyloctane

    4-ethyl-2,2-dimethyldecane

    2,2-dimethylpentane

    2,2-dimethylbutane

Draw the structural formula of the following alkenes:

    1-butene

    2-butene

    4-decene

    propene

Draw the structural formula of the following alkynes:

    3-heptyne

    2-butyne

    3-hexyne

    4-decyne

 

Isomerism starts with butane.

Example

Butane, C4H10  or CH3CH2CH2CH3

methylpropane, C4H10 or CH3CHCH3CH3

 

Problems

1. Write the structural formula and name of all isomers having the molecular formula C5H12

2. Write the structural formula and name of all isomers having the molecular formula C6H14

3. Write the structural formula and name of all isomers having the molecular formula C7H16

 

TEST YOUR UNDERSTANDING

1/07

22 Given the structural formula:

What is the IUPAC name of this compound?  (1) pentanal (2) pentanol (3) methyl pentanoate (4) pentanoic acid

28 Given the structural formula:

What is the total number of electrons shared in the bond between the two carbon atoms?  (1) 6 (2) 2 (3) 3 (4) 4

Base your answers to questions 82 and 83 on the information below.

A gasoline engine burns gasoline in the presence of excess oxygen to form carbon dioxide and water. The main components of gasoline are isomers of octane. A structural formula of octane is shown below.

One isomer of octane is 2,2,4-trimethylpentane.

82 Draw a structural formula for 2,2,4-trimethylpentane.

83 Explain, in terms of the arrangement of particles, why the entropy of gasoline vapor is greater than the entropy of liquid gasoline.

8/07

22 A molecule of butane and a molecule of 2-butene both have the same total number of    (1) carbon atoms (2) hydrogen atoms (3) single bonds (4) double bonds

23 Which general formula represents the homologous series of hydrocarbons that includes the compound l-heptyne?

(1) CnH2n–6 (2) CnH2n–2 (3) CnH2n (4) CnH2n+2

8/02

Given the structural formula for butane: Draw the structural formula of an isomer of butane.

1/03 

Which compound has an isomer?

6/03

21. Which hydrocarbon is saturated? (1) propene     (2) ethyne  (3) butene  (4) heptane

25. Which compound is an isomer of pentane? (1) butane (2) propane  (3) methyl butane (4) methyl propane

6/04

46 Which structural formula represents 2-pentyne?

 

8/04

22 What is the IUPAC name of the compound with the structural formula shown below?

                (1) 2-pentene (2) 3-pentene (3) 2-pentyne (4) 3-pentyne

1/05

20 What is the total number of electron pairs that are shared between the two carbon atoms in a molecule of ethyne? (1) 1 (2) 2 (3) 3 (4) 4

62 Identify the homologous series of hydrocarbons to which CH3CHCH2 belongs.

6/05

22 Which formula represents an unsaturated hydrocarbon? (1) C2H6 (2) C3H8 (3) C5H8 (4) C6H14

23 Given the structural formula:

 

What is the IUPAC name of this compound? (1) propane (2) propene (3) propanone (4) propanal

25 The three isomers of pentane have different (1) formula masses (2) molecular formulas (3) empirical formulas (4) structural formulas

1/06

19 The multiple covalent bond in a molecule of 1-butene is a

        (1) double covalent bond that has 6 shared electrons (2) double covalent bond that has 4 shared electrons

        (3) triple covalent bond that has 6 shared electrons (4) triple covalent bond that has 4 shared electrons

55 Given the structural formula of pentane:

 

Draw a structural formula for an isomer of pentane.

6/06

20 Which formula represents propyne?

43 What is the IUPAC name for the compound that has the condensed structural formula CH3CH2CH2CHO?

        (1) butanal (2) butanol (3) propanal (4) propanol

55 To which homologous series does CH3CH2CH2CH3 belong?

8/06

23 Given the structural formulas:

Which two formulas represent compounds that are isomers of each other?

        (1) A and B   (2) A and C   (3) B and D   (4) C and D

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