Unit 3 Organic Chemistry Chemistry 2202 Introduction Organic Chemistry is the study of the molecular...

Unit 3Organic Chemistry

Chemistry 2202

Introduction

Organic Chemistry is the study of the molecular compounds of carbon.eg. CH4 CH3OH CH3NH2

Organic compounds exclude oxides of carbon and ions containing carbon.ie. CO CO2 KCN CaCO3

are NOT organic compounds!!

History of Organic Chemistry

Started when medicine men extracted chemicals from plants and animals as treatments and cures

First defined as a branch of modern science in the early 1800's by Jon Jacob Berzelius

Berzelius believed in Vitalism - organic compounds could only originate from living organisms through the action of some vital force

organic compounds originate in living or once-living matter

inorganic compounds come from "mineral" or non-living matter

In 1828, Friedrich Wöhler discovered that urea - an organic compound - could be made by heating ammonium cyanate (an inorganic compound).

NH4OCN(aq) (NH2)2CO(s)

inorganic organic

What’s this?

(NH2) 2CO - (NH2)2CO

di-urea

organic chemistry branched into disciplines such as polymer chemistry, pharmacology, bioengineering and petro-chemistry

98% of all known compounds are organic

The huge number of organic compounds is due mainly to the ability of carbon atoms to form stable chains, branched chains, rings, branched rings, multiple rings, and multiple bonds (double and triple bonds) to itself and to many other non-metal atoms.

Some more Organic notes

Sources of Organic Compounds

1. Carbonized Organic Matter- fossil fuels such as coal, oil, and

natural gas - basis for the petrochemical industry

2. Living Organisms eg: - penicillin from mold

- ASA from the bark of a willow tree

3. Invention

- antibiotics, aspirin, vanilla flavoring, and heart drugs are manufactured from organic starting materials

- plastics

Structural Isomers

Structures that have the same molecular formula but different structural formulas are called structural isomers

eg. C4H10

Practice: Draw all structural isomers of C5H12 and C6H14

Structural Isomers

structural isomers have the same chemical formula but have different chemical and physical properties.

Classifying Organic Compounds Organic

Compounds

Hydrocarbons HydrocarbonDerivatives

• Alcohols• Ethers• Aldehydes• Ketones• Carboxylic Acids• Alkyl Halides• Esters• Amines• Amides

Aliphatic

AlkAnes

AlkEnes

AlkYnes

Aromatic (benzene based)

hydrocarbons consist of carbon

and hydrogen atoms only

eg. Methane - CH4 hydrocarbon derivatives have one

or more hydrogen atoms replaced by another nonmetallic atom

eg. bromomethane - CH3Br

methanol - CH3OH

aliphatic hydrocarbons have carbon atoms bonded in chains or rings with only single, double, or triple bonds

aromatic hydrocarbons contain at least one 6 carbon benzene ring

Aliphatic Hydrocarbons

1. AlkanesAlkanes are hydrocarbons that have

only single bonds between carbon atoms

general formula CnH2n+2

eg. C3H8 C6H14

IUPAC prefixes

Prefix # of carbon atoms

meth 1

eth 2

prop 3

but 4

pent 5

hex 6

hept 7

oct 8

non 9

dec 10

Complete this table for the first 10 alkanes

methane CH4

ethane

propane

A series of compounds which differ by the same structural unit is called a homologous series

eg. each alkane increases by CH2

What is the next member of this homologous series?

SiO2 Si2O3 Si3O4 _____

Representing Alkanes (4 ways)

1. Structural formulas

eg. propane

H – C – C – C – H

HHH

HHH

Hydrogen atoms may be omitted from structural formulas

eg. propane

– C – C – C –

2. Condensed Structural Formula

eg. propaneCH3-CH2-CH3

3. Line Structural Diagrams

eg: propane

(the endpoint of each segment is a carbon atom)

4. Expanded Molecular Formulas

eg. propane

CH3CH2CH3

p. 333

An alkyl group has one less hydrogen than an alkane.

General Formula: CnH2n + 1

To name an alkyl group, use the prefix to indicate the # of carbon atoms followed by the suffix –yl

eg. -C7H15 heptyl

Alkyl Groups

Alkyl Groups

methyl  -CH3

ethyl  -C2H5  or  -CH2CH3

propyl  -C3H7  or  -CH2CH2CH3

Branched alkanes are alkanes that contain one or more alkyl groups

eg.

Alkyl Groups

1. Find the longest continuous chain of carbons(parent chain) and name it using the alkane name.

2. Number the carbons in the parent chain starting from the end closest to branching. These numbers will indicate the location of alkyl groups.

Naming Branched Alkanes

Naming Branched Alkanes

3. List the alkyl groups in alphabetical order. Use Latin prefixes if an alkyl group occurs more than once. (di = 2, tri = 3, tetra = 4, etc.)

4. Use a number to show the location of each alkyl group on the parent.

5. Use commas to separate numbers, and hyphens to separate numbers and letters. 

Naming Branched Alkanes

eg.

7 6 5 4 3 2 1

ethyl

methyl

4-ethyl-3-methylheptane

Naming Branched Alkanes

Practice:p. 336 - 339 #’s 5 – 11

(Answers on p. 375)

Naming Branched Alkanes

Alkenes and Alkynes

saturated hydrocarbons contain only single bonds between carbon atoms

eg. alkanessaturated hydrocarbons have the

maximum number of hydrogen atoms bonded to carbon atoms

Alkenes and Alkynes

unsaturated hydrocarbons contain double or triple bonds between carbon atoms

eg. alkenes and alkynes

Alkenes and Alkynes

General Formulas:

Alkenes CnH2n

Alkynes CnH2n - 2

At least one double bond

At least one triple bond

Naming Alkenes and Alkynes

1. Name the longest continuous chain that contains the double/triple bond.

2. Use the smallest possible number to indicate the position of the double or triple bond.

Naming Alkenes and Alkynes

3. Branches are named using the same rules for alkanes.

4. Number the branches starting at the same end used to number the multiple bond.

Naming Alkenes and Alkynes

p. 347 #’s 17 - 19p. 354 #’s 28 & 29

Cyclic Hydrocarbons

Pp. 356 – 358questions 30 & 31

cyclopentane

methylethyl

1-ethyl-3-methylcyclopentane

3-ethyl-1-methylcyclopentane

1

2

3

methyl

1,2,3,4-tetramethylcyclohexane

Aromatic Compounds

Aromatic hydrocarbons contain at least one benzene ring.

The formula for benzene, C6H6 , was determined by Michael Faraday in 1825.

The structural formula was determined by August Kekulé in 1865.

Aromatic Compounds

Proposed formula:

Conflicting Evidence

C=C double bonds are shorter than C-C single bonds. X-ray crystallography shows that all C-C bonds in benzene are the same length.

Benzene reacts like an alkane, not like an alkene.

Modified structure

Kekulé proposed a resonance structure for benzene.

The resonance structure is an average of the electron distributions.

Aromatic Compounds

or

Aromatic Compounds

bonding electrons, once believed to be in double bonds, are delocalized and shared equally over the 6 carbon atoms

the bonds in benzene are like “1½” bonds – somewhere between single and double.

Naming Aromatic Compoundsan alkyl benzene has one or more H

atoms replaced by an alkyl group.name the alkyl groups, using

numbers where necessary, followed by the word benzene.

Aromatic Compounds

methylbenzene

propylbenzene

ethylbenzene

Aromatic Compounds

1,3-dimethylbenzene

1,4-dimethylbenzene

1,2-dimethylbenzene

Aromatic Compounds

ortho- means positions 1 and 2 and is represented by "o"

meta- means positions 1 and 3 and is represented by "m"

para- means positions 1 and 4 and is represented by "p"

Aromatic Compounds

m-dimethylbenzene

p-dimethylbenzene

o-dimethylbenzene

Aromatic Compounds

Benzene is treated as a branch if it is not attached to the terminal carbon of an alkyl group

Benzene as a branch is called phenyl

Aromatic Compounds

CH2

CH2

CH3

CH3CHCH3

propylbenzene2-phenylpropane

Aromatic Compounds

CH3CHCHCH2CH2CH3

CH2CH3

Aromatic Compounds

CH3CHCHCH2CHCH2CH2CH3

CH2

CH2

CH3

CH3

Aromatic Compounds

p. 361 #’s 32 – 35

Hydrocarbons Practice

pp. 363, 364

#’s 4 – 9

Test!!

cis and trans isomers (p. 348)

Properties of aliphatic hydrocarbons

Because they are nonpolar, all hydrocarbons are insoluble in water.

The boiling point of alkanes is somewhat higher than alkenes but lower than alkynes.

As the number of atoms in the hydrocarbon molecule increases, the boiling point increases.

Reactions

Complete the aliphatic hydrocarbons worksheet using these references:

a) complete combustion (p. 340)

b) incomplete combustion (p. 340)

c) substitution reaction (p. 344, 362)

d) addition reaction (p. 349)

Hydrocarbon Derivatives

hydrocarbon derivative - contains other nonmetal atoms such as O, N, or halogen atoms.

9 types functional group - the reactive group

of atoms that gives a family of derivatives its distinct properties

Hydrocarbon Derivatives

The general formula for a derivative is

R - functional group

where R stands for any alkyl group.

Hydrocarbon Derivatives

eg. ALCOHOLS R-OH

ethanol C2H5OH

propanol C3H7OH

CARBOXYLIC ACIDS R-COOH

ethanoic acid CH3COOH

propanoic acid C2H5COOH

1. Alcohols

Have the hydroxyl functional group

General Formula: R - OH

Naming Alcohols (p. 387)

The parent alkane is the longest chain that has an -OH group

Replace the last -e in the alkane name

with the suffix -ol.Add a number to indicate the location of

the -OH group.

C OH

H

H

H

CC O

H

H

H

H

H

H

methanol

ethanol

eg. CCC O

H

H

H

H

H

H

H

H

CCC

O

H

H

HH

H

H

H

H

Properties of Alcohols (p. 389)

Alcohols have H-bonding which makes their mp and bp higher than the corresponding alkane.

Polarity decreases as the # of carbon atoms increases

Long chain alcohols are less soluble in water than short chain alcohols.

Reactions of alcohols

Combustion

R-OH + O2 → CO2 + H2O

eg. Write the equation for the burning of butanol.

Reactions of alcohols

Substitution

R-OH + H-X → R-X + H2O

eg. Use structural formulas to show the reaction between 2-pentanol and HBr.

Reactions of alcohols

Elimination (Dehydration)

eg.

CCC OH

H

H

HHH

HH

H2SO4CCC HHH

HH

H

+ H2O

P. 393 16 a), d), 18 a), b), d) & e)

(Draw structural formulas for the products in #18)

2. Ethers

Composed of two alkyl groups bonded to an oxygen atom.

General Formula: R1-O-R2

Naming ethers: p. 395IUPAC nameCommon name

O C C

H

H

H

H

H

CH

H

H

O C C C C

H

H

H

H

H

H

H

H

H

CCC

H

H

H

H

H

H

H

O C C

H

H

H

H

H

CC

H

H

H

H

H

P. 395, 396 #’s 20 – 23

Worksheet: Ethers

3. Aldehydes (p. 402)

Contain a carbonyl functional group at the end of a carbon chain.

General Formula:- =

HR-C

O

Naming:Use the alkane name for the longest

continuous chain.Remove the –e and add the suffix –aleg.

butane → butanal

CCCC O

HH

H

H

H

H

H

H

4. Ketones (p. 402)

Contain a carbonyl functional group in the ‘middle’ of a carbon chain.

ie. NOT on carbon #1

General Formula:

=O

- R2R1-C

Naming:Use the alkane name for the longest

continuous chain.Replace the –e with the suffix –oneUse the smallest possible number for

the position of the C=O group.

CCCC

O

H

H

H

H

H

H

H

H

CCCCC

O

H

H

H

H

H

H

H

H

H

H

p. 403 #’s 28 - 31

Handout: Aldehydes and Ketones

5. Carboxylic Acids (p. 405)

Contain a carboxyl functional group

ie. -COOH

General Formula:

AKA: Organic Acids

=O

- OHR1-C

CCC OH

OH

H

H

H

H

Text; p. 406 #’s 32 - 35

C C C CO

O H

H

H

H

H

H

H

H

6. Alkyl Halides (p. 390, 391)

Contain at least one halogen atom

General Formula: R – X

(X is F, Cl, Br, or I)

Text; p. 391 #’s 12 – 15

Worksheet: Organic # 8

CCCC

Br

Br

Br

H

H

HH

H

H

H

CCCCC

Cl

Br

BrBr

Br

H

HHH

H

H

H

Text; p. 406 #’s 32 - 35

Elimination - Alcohols

eg.

CCC OH

H

H

HHH

HH

H2SO4CCC HHH

HH

H

+ H2O

Δ

Elimination – Alkyl Halides

eg.

CCC I

H

H

H

H

H

H

H

+ H2O + I-

+ OH- → CCC H

HH

H

H

H

p.393 #’s 18 c) and f)

7. Esters (pp. 410, 411)

Form when a carboxylic acid reacts with an alcohol

General Formula:

Esterification Reaction:carboxylic acid + alcohol → ester + water

=

- O-R2R1-C

O

Naming:

- the parent is named by replacing the

– oic acid ending from the acid with – oate

- the alcohol is identified by using the corresponding alkyl group

pp. 411, 412 #’s 36 - 40

8. Amines (pp. 410, 411)

Form when a carboxylic acid reacts with an alcohol

General Formula: R – NH2

Cracking & Reforming

‘Cracking‘ is a reaction that break long chain hydrocarbons into smaller fragments.

eg.

decane + H2 → ethane + octane

Reactions – Organic Compounds

Combustion (p. 340)

Substitution (p. 344)

Esterification (p. 410)

Elimination (p. 390)

Cracking & Reforming

‘Reforming’ is a reaction that combines smaller hydrocarbons to make long chain hydrocarbons

eg.

ethane + butane → hexane + H2

Review - Derivatives

pp. 400, 401

Omit: 1a), 2c) & d), 3b) & e), 5b),

8, 10b) & c), 11b) & d)

pp. 419, 420

Omit: 1g), 3d), 4a), 7, 8c), 10