ChemPhys UNIT 7: Organic Chemistry

Chemistry & Physics

UNIT 7: ORGANIC CHEMISTRY

Chemistry

Periodic table

Chemical reaction

Matter

Atoms

Chemical bonding

Electrolytes

Hydrocarbons

Organic chemistry

Today

• Introduction

– Organic vs. Inorganic

– Formulas

– Isomerism

• Alkanes

– Naming

• Alkenes and alkynes

– Naming

– Geometric isomers

– Biologically important alkenes

PreQuiz

1. Which of the following is an organic substance?

a) Water; b) Salt; c) Diamond

2. What type of bonding is usually found in organic compounds?

a) Covalent bonding; b) Ionic bonding; c) Hydrogen bonding

3. The molecular and emperical formula of ethane are _____?

a) C2H6 / C2H6; b) C2H6 / CH3; c) C2H6 / C4H12

4. HC≡CH is part of the family of the _____?

a) Alkanes; b) Alkenes; c) Alkynes

5. Alkanes react primarily by _____?

a) Neutralization; b) Substitution; c) Addition

6. Haloalkanes are often used as _____?

a) Disinfectant; b) Anestetics; c) Hormones

7. β-carotene is a(n)_____?

a) Plant hormone; b) Aromatic ; c) Precursor of Vitamin A

8. Cis- and trans-2-butene are examples of _____?

a) cycloalkenes; b) geometric isomers; c) lazy chemicals

9. What is the name of the following compound:

a) 3-methyl-1-butene; b) 2-methyl-3-butyne; c) 3-methyl-1-butane

Organic chemistry

BONDING

FORMULAS

ISOMERS

Organic materials

ORGANIC MATTER

Chemistry of life

Sackheim’s Chemistry: Chapter 14

Organic vs. inorganic

Organic Inorganic

Based on C Not based on C

Nonelectrolyte Electrolyte (acids, bases, salts)

Covalent bonding Ionic bonding

Low boiling and melting point High boiling and melting point

Soluble in nonpolar solvents Soluble in polar solvents (water)

Complex structure Simple structure

Millions of compounds Thousands of compounds


UniqueCovalent bonds with itselfCovalent bonds with others

C-C bonds

• Carbon-Carbon (C-C) bond

– Unique: covalent bonds with other C atoms

– 4 valence (outer) electrons: maximum of 4 covalent bonds


Covalent bonds“Sharing electrons”

C-C compounds

GraphiteGood electrical

conduction

DiamondHardest natural

substance

Fullerene Nanotube


Create Carbon

C-H bonds

• Carbon-Hydrogen (C-H) bond

– Each carbon atom forms 4 bonds: octet rule

– Each hydrogen atom form 1 bond

– Alkane: single bond

– Alkene: double bond

– Alkyne: triple bondSackheim’s Chemistry: Chapter 14

Alkane

Alkene

Alkyne

Other C bonds

• Carbon-Oxygen (C-O) and Carbon-Fluor (C-F) bond

– Each carbon atom forms 4 bonds: octet rule

– Each oxygen atom forms 2 bonds (double bond): octet rule

– Each fluor atom forms 1 bond: octet rule


Formulas

• Definition

– Group of symbols that represent the elements present in a substance

• Molecular formula

– Written formula

– Presents actual number of atoms in the substance

– Cannot tell the structure

• Structural formula

– 2D view of structure

– Presents connection between atoms


“ISOMERS”

Isomerism

• Isomers

– Same molecular structure

– Different structural formula: different properties

Boiling point = 78 °Cliquid

-25 °Cgas


Nomenclature

• Naming of chemical compounds

– Via IUPAC system

Carbonatoms

Alkanes Alkenes Alkynes

1 CH4: methane - -

2 C2H6: ethane C2H4: ethene C2H2: ethyne

3 C3H8: propane C3H6: propene C3H4: propyne

4 C4H10: butane C4H8: butene C4H6: butyne

5 C5H12: pentane C5H10: pentene C5H8: pentyne

6 C6H14: hexane C6H12: hexene C6H10: hexyne

Sackheim’s Chemistry: Chapter 15,16

Saturated hydrocarbons

NAMES

STRUCTURE

PROPERTIES

USE

Source of hydrocarbons


Natural gas

Petroleum

Alkanes

• Hydrocarbons = compounds with C and H only

– SATURATED (alkanes): single bonds


Methane: (CH4) General formula: CnH2n+2

Free rotation vs. isomers

• Same compounds

– Rotation of C-C single bonds

– All structures are the same

– C4H10: butane

• Isomer

– Same molecular formula

– Different structural formula

– C4H10: iso-butane


Lazy scientists

• Condensed structural formulas

CH3-CH2-CH2-CH3

CH3CH2CH2CH3

CH3(CH2)2CH3 deg

ree

of

lazi

nes

s


Nomenclature alkanes

• IUPAC system

1. Search for longest carbon chain (head chain) and name it

2. Number the carbon atoms of the head chain

3. Search for side groups that are not part of head chain andname them

Carbonatoms

Head chain Side group

1 CH4: methane –CH3: methyl

2 C2H6: ethane –C2H5: ethyl

3 C3H8: propane –C3H7: propyl

4 C4H10: butane –C4H9: butyl

5 C5H12: pentane –C5H11: pentyl

6 C6H14: hexane –C6H13: hexyl

7 C7H16: heptane –C7H15: heptyl

8 C8H18: octane –C8H17: octyl

9 C9H20: nonane –C9H19: nonyl

10 C10H22: decane –C10H21: decyl


Practice (1)

• IUPAC system

1. Search for longest carbon chain (head chain) and name it

2. Number the carbon atoms of the head chain

3. Search for side groups that are not part of head chain andname them

Butane

2-methylbutane

Octane

2,3-dimethyl-4-ethyloctane

1 2 3 4

8 7 6 5 4 3 2 1


Practice (2)

2-ethyl-3-chloro-4-methylheptane

1 2 3 4 5 6 7


Cycloalkanes

• Shape of ring

– Prefix: cyclo-

– Structures can be abbreviated with geometric shape


Properties

Carbonatoms

Formula andname

Boilingpoint (°C)

State of matter

1 CH4: methane -162 Gas

2 C2H6: ethane -89 Gas

3 C3H8: propane -42 Gas

4 C4H10: butane 0 Gas

5 C5H12: pentane 36 Liquid

6 C6H14: hexane 69 Liquid

7 C7H16: heptane 98 Liquid

8 C8H18: octane 126 Liquid

9 C9H20: nonane 151 Liquid

10 C10H22: decane 174 Liquid


Combustion

• Complete combustion

– Alkanes react with oxygen to produce carbon dioxide, water and energy

• Incomplete combustion

– Alkanes produce also carbon monoxide (poisoning) due to insufficient O2


Halogenation

• Substitution

– Alkanes react with halogens (F2, Cl2, Br2, I2)

– Halogen (F, Cl, Br, I) replaces hydrogen (H)

– Product: haloalkane

bromomethane

chloromethane dibromomethanetriiodomethane


substitution

Anesthetics


cyclopropane chloroethane

“chloral hydrate” “halothane”

Unsaturated hydrocarbons

NAMES

STRUCTURE

PROPERTIES

USE

Alkenes



– UNSATURATED (alkenes or alkynes): double or triple bonds


Ethene: (C2H4) General formula: CnH2n

Cycloalkenes

• Shape of ring

– Prefix: cyclo-

– Structures can be abbreviated with geometric shape


Alkynes



– UNSATURATED (alkenes or alkynes): double or triple bonds


Ethyne: (C2H2) General formula: CnH2n-2

Nomenclature alkenes and alkynes

• IUPAC system

1. Search for longest carbon chain (head chain) with double/triple bond and name it

2. Number the carbon atoms of the head chain and give lowest numberpossible to double bond

3. Search for side groups that are not part of head chain and name them

Carbonatoms

Alkanes Alkenes Alkynes

1 CH4: methane - -

2 C2H6: ethane C2H4: ethene C2H2: ethyne

3 C3H8: propane C3H6: propene C3H4: propyne


Practice (3)

• IUPAC system





Butene

1-butene

3-methyl-1-butene

4 3 2 1

Cyclohexene

1-cyclohexene

3-methyl-1-cyclohexene

1 2

5 4

6 3

Practice (4)

• IUPAC system





Octyne

2-octyne

4,4-dibromo-5-ethyl-6-methyl-2-octyne

1 2 3 4 5 6 7 8

Practice (5)

• IUPAC system





3,4-diethyl-2-hexene

1 2 3 4 5 6

Addition

• Reactions with alkenes/alkynes

– Addition: from unsaturated to saturated


hydrogenation

halogenation

Geometric isomers

no free rotation

“Same molecular formula but different structural formula”

same side opposite side

4 °C 0 °C


Biological importance

• Ethene

– Plant hormone (ripening fruits)

• Linoleic acid

– Found in nuts and oils (essential for body)

• Arachidonic acid

– Found in meat, eggs, diary (essential for body)

• β-carotene

– In fruits and vegetables (precursor vitamin A)

• Vitamin A

– From β-carotene (essential for body)

• Isoprene

– Present in natural rubber (industrial use) Sackheim’s Chemistry: Chapter 16

Aromatics

• Unsaturated hydrocarbons

– Pleasant odor

– Special ring-shaped structure


Benzene derivatives

Toluene

XylenePhenanthrene

TNT


PostQuiz

1. Which of the following is an organic substance?

a) Water; b) Salt; c) Diamond

2. What type of bonding is usually found in organic compounds?

a) Covalent bonding; b) Ionic bonding; c) Hydrogen bonding

3. The molecular and emperical formula of ethane are _____?

a) C2H6 / C2H6; b) C2H6 / CH3; c) C2H6 / C4H12

4. HC≡CH is part of the family of the _____?

a) Alkanes; b) Alkenes; c) Alkynes

5. Alkanes react primarily by _____?

a) Neutralization; b) Substitution; c) Addition

6. Haloalkanes are often used as _____?

a) Disinfectant; b) Anestetics; c) Hormones

7. β-carotene is a(n)_____?

a) Plant hormone; b) Aromatic ; c) Precursor of Vitamin A

8. Cis- and trans-2-butene are examples of _____?

a) cycloalkenes; b) geometric isomers; c) lazy chemicals

9. What is the name of the following compound:

a) 3-methyl-1-butene; b) 2-methyl-3-butyne; c) 3-methyl-1-butane

The End

Education

ChemPhys UNIT 7: Organic Chemistry