C HAPTER 10 I NTRODUCTION TO O RGANIC C HEMISTRY : A LKANES 10.1 Organic Compounds 1 Copyright © 2009 by Pearson Education, Inc.

O RGANIC C HEMISTRY An organic compound is a compound made from carbon atoms. has one or more C atoms. has many H atoms. may also contain O, S, N, and halogens. 2

O RGANIC C OMPOUNDS Typical organic compounds have covalent bonds. have low melting points. have low boiling points. are flammable. are soluble in nonpolar solvents. are not soluble in water. 3 oil (organic) and water (inorganic )

O RGANIC VS. I NORGANIC Propane, C 3 H 8, is an organic compound used as a fuel. NaCl, salt, is an inorganic compound composed of Na + and Cl − ions. Why is propane organic, but NaCl is not? 4

C OMPARING O RGANIC AND I NORGANIC C OMPOUNDS 5

L EARNING C HECK Identify each characteristic as most typical of compounds that are 1) inorganic or 2) organic. A. has a high melting point. B. is not soluble in water. C. has a formula CH 3 ─CH 2 ─CH 3. D. has a formula MgCl 2. E. burns easily in air. F. has covalent bonds. 6

W RITING F ORMULAS FOR A LKANES In organic compounds, carbon has 4 valence electrons and hydrogen has 1. C H carbon achieves an octet by forming four bonds. H H  H  C  H H C H  H H CH 4, methane 7

T ETRAHEDRAL S TRUCTURE OF C ARBON VSEPR theory predicts that a carbon atom with four single, covalent bonds has a tetrahedral shape. 8

O RGANIC M OLECULES In organic molecules, valence electrons are shared. covalent bonds form between carbon atoms. H H H H H  C  C  HH C C H H H H H Ethane, CH 3 ─CH 3 9

T ETRAHEDRAL S TRUCTURE OF C ARBON In molecules with two or more carbon atoms, each carbon atom with four single bonds has a tetrahedral shape. 10

C HAPTER 10 I NTRODUCTION TO O RGANIC C HEMISTRY : A LKANES 10.2 Alkanes 11

S TRUCTURAL F ORMULAS Alkanes are written with structural formulas that are expanded to show each bond. condensed to show each carbon atom and its attached hydrogen atoms. Expanded Condensed H H C H CH 4, methane H 12

E XPANDED AND C ONDENSED S TRUCTURES 13 Copyright © 2009 by Pearson Education, Inc.

S TRUCTURAL F ORMULAS Condensed formulas are written for expanded structural formula by showing each carbon and the attached hydrogen atoms. Expanded Condensed H H H H │ │ │ │ H─C ─C ─C ─C ─ H CH 3 ─CH 2 ─CH 2 ─CH 3 │ │ │ │ H H H H 14

N AMES OF A LKANES The names of alkanes are determined by the IUPAC (International Union of Pure and Applied Chemistry) system. end in – ane. with 1-4 carbons in a chain use prefixes as follows: Name # Carbons Condensed Structural Formula Meth ane1 C H 4 Eth ane2 C H 3 ― C H 3 Prop ane3 C H 3 ― C H 2 ― C H 3 But ane4 C H 3 ― C H 2 ― C H 2 ― C H 3 15

N AMES OF A LKANES Alkanes with 5-10 carbon atoms in a chain use Greek prefixes. Name # Carbons Structural Formula Pent ane 5CH 3 CH 2 CH 2 CH 2 CH 3 Hex ane 6 CH 3 CH 2 CH 2 CH 2 CH 2 CH 3 Hept ane 7 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Oct ane 8 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Non ane 9 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Dec ane 10 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 16

W RITING S TRUCTURAL F ORMULAS Carbon atoms in a chain maintain tetrahedral shape. are connected in a zigzag pattern. are drawn as 2-dimensional. can be written in several conformations. 17

S OME S TRUCTURES FOR B UTANE 18 Copyright © 2009 by Pearson Education, Inc.

H EXANE H AS S IX C ARBON A TOMS Hexane is an alkane with six carbon atoms in a continuous chain. has a “zigzag” look because each carbon atom is at the center of a tetrahedron. is represented by a ball-and-stick model as shown below. 19 Copyright © 2009 by Pearson Education, Inc.

L EARNING C HECK A. Write the condensed formula for: B. What is its molecular formula? C. What is its name? 20

L EARNING C HECK Write the condensed structural formula for A. ethane. B. heptane. 21

E XAMPLES Write condense structure for

C YCLOALKANES Cycloalkanes are cyclic alkanes. have two hydrogen atoms fewer than the open chain. are named by using the prefix cyclo - before the name of the alkane chain with the same number of carbon atoms. 23

C YCLOALKANES 24 The structural formulas of cycloalkanes are usually represented by geometric figures. Copyright © 2009 by Pearson Education, Inc.

M ORE C YCLOALKANES 25

L EARNING C HECK Name the following. A. CH 3 ─CH 2 ─CH 2 ─CH 3 B. C. CH 3 ─CH 2 ─CH 2 ─CH 2 ─CH 2 ─CH 2 ─CH 2 ─CH 3 D. E. 26

C HAPTER 10 I NTRODUCTION TO O RGANIC C HEMISTRY : A LKANES 10.3 Alkanes with Substituents 27

I SOMERS OF B UTANE Isomers have the same molecular formula. have different atom arrangements. of butane (C 4 H 10 ) are a straight chain and a branched chain. 28

A LKYL GROUPS Alkyl groups are alkanes that are missing one H. substituents attached to carbon chains. named with a –yl ending. CH 3 methyl CH 3 CH 2 ethyl 29

N AMING S UBSTITUENTS In the IUPAC system, a carbon branch is named as an alkyl group. halogen atoms are named as halo. 30

G UIDE TO N AMING A LKANES 31

A LKANES WITH S UBSTITUENTS CH 3 CH 3 CH CH 3 methylpropane methyl groups CH 3 CH 3 CH 3 CH CH 2 CH CH 3 2,4-dimethylpentane 32

N AMING A LKANES Give the name of CH 3 CH 3  CH 3 ─CH─CH─CH 3 STEP 1: Name the longest continuous chain. STEP 2: Number chain. STEP 3: Locate substituents and name. 33

N AMING H ALO - ALKANES Step 1: determine the long chain Name it as parent chain Step 2: identify substituents Akyl – all CH Halo – halogen Chlorine  Chloro Bromine  bromo number carbon starting from the end closet to the substituent Step 3: name the molecule in alphabetical order. Location-substituentparent chain

E XAMPLE Name the following molecules

L EARNING C HECK Write the name of Cl CH 3  CH 3 ─CH 2 ─CH─CH─CH 3 36

L EARNING C HECK Give the IUPAC name for each of the following: A. CH 3 CH 3 | CH 3 ─CH─CH 2 ─CH─CH 3 B. Cl CH 3 | | CH 3 ─CH 2 ─CH─CH 2 ─C─CH 2 ─CH 3 | Cl 37

G UIDE TO D RAWING A LKANE F ORMULAS 38

L EARNING C HECK Draw the condensed structural formula for 3-bromo-1-chlorobutane. 39 STEP 1: Longest chain has 4 carbon atoms. STEP 2: Number chain and add substituents. TEP 3: Add hydrogen to complete 4 bonds to each C.

N AMING C YCLOALKANES WITH S UBSTITUENTS The name of a substituent is placed in front of the cycloalkane name. CH3 methyl cyclobutane Cl Chloro cyclopentane 40

L EARNING C HECK Name each of the following. 1. CH 3 CH 2 ─CH

C HAPTER 10 I NTRODUCTION TO O RGANIC C HEMISTRY : A LKANES 10.4 Properties of Alkanes 42

S OME P ROPERTIES OF A LKANES Alkanes are nonpolar. insoluble in water. less dense than water. flammable in air. 43

S OME P ROPERTIES OF A LKANES Alkanes with 1-4 carbon atoms are methane, ethane, propane, and butane. gases at room temperature. used as heating fuels. 44

S OME P ROPERTIES OF A LKANES Alkanes with 5-8 carbon atoms are liquids at room temperature. pentane, hexane, heptane, and octane. very volatile. used to make gasoline. Alkanes with 9-17 carbon atoms are liquids at room temperature have higher boiling points. are found in kerosene, diesel, and jet fuels. 45

S OME P ROPERTIES OF A LKANES Alkanes with 18 or more carbon atoms have high molar masses. are waxy solids at room temperature. used in waxy coatings of fruits and vegetables. 46 Copyright © 2009 by Pearson Education, Inc.

C OMBUSTION In combustion reactions, alkanes react with oxygen. CO 2, H 2 O, and energy are produced. Alkane + O 2 CO 2 + H 2 O + heat 47 Copyright © 2009 by Pearson Education, Inc.

L EARNING C HECK Write a balanced equation for the complete combustion of propane. 48

C HAPTER 10 I NTRODUCTION TO O RGANIC C HEMISTRY : A LKANES 10.5 Functional Groups 49

E LEMENTS IN O RGANIC C OMPOUNDS In organic molecules, carbon atoms bond with four bonds. mostly with H and other C atoms. sometimes to O, N, S. sometimes to halogens F, Cl, and Br. 50 Copyright © 2009 by Pearson Education, Inc.

F UNCTIONAL G ROUPS Functional groups are a characteristic feature of organic molecules that behave in a predictable way. composed of an atom or group of atoms. groups that replace a hydrogen atom in the corresponding alkane. a way to classify families of organic compounds. 51

A LKENES, A LKYNES, AND A ROMATIC C OMPOUNDS Alkenes contain a double bond between adjacent carbon atoms. Alkynes contain a triple bond. Aromatic compounds contain a ring of six carbon atoms called benzene. 52

C OMPARING A LKENES, A LKYNES, AND A ROMATIC C OMPOUNDS 53

A LCOHOLS AND E THERS An alcohol contains the hydroxyl (-OH) functional group. A thiol contains the thiol (-SH) functional group. An ether contains an oxygen atom bonded to two carbon atoms. 54

A LDEHYDES AND K ETONES An aldehyde contains a carbonyl group (C=O), which is a carbon atom with a double bond to an oxygen atom. The carbonyl is attached to a hydrogen. In a ketone, the carbon of the carbonyl group (C=O) is attached to two carbon atoms. 55 Copyright © 2009 by Pearson Education, Inc,

C ARBOXYLIC A CIDS AND E STERS Carboxylic acids contain the carboxyl group, which is a carbonyl group attached to a hydroxyl group. O ║ — C—OH An ester contains the carboxyl group between carbon atoms. 56

A MINES AND A MIDES In amines, the functional group is a nitrogen atom. | —N — In amides, the hydroxyl group of a carboxylic acid is replaced by a nitrogen group. 57 Copyright © 2009 by Pearson Education, Inc. Amines An amide

S UMMARY OF F UNCTIONAL G ROUPS 58

L EARNING C HECK Classify each of the following as: alcohol, ether, aldehyde, ketone, carboxylic acid, ester, amine, or amide. 59