Chapter 22

Carbon & Hydrocarbons

• Diamond• Graphite• Fullerenes• Delocalized electrons• Organic compounds• Catenation• Hydrocarbons• Isomers• Structural formula• Structural isomers• Geometric isomers

• Saturated hydrocarbon• Alkanes• Cycloalkanes• Alkyl groups• Natural gas• Petroleum• Unsaturated hydrocarbons• Alkynes• Aromatic hydrocarbons• benzene

Chapter 22 Vocabulary

• Diamond is a colorless, crystalline, solid form of carbon• Graphite is a soft, black, crystalline form of carbon that is a

fair conductor of electricity• Fullerenes are dark colored solids made of spherically

networked carbon atom cages.• Delocalized electrons are electrons shared by more than

two atoms• Organic compounds covalently bonded compounds

containing carbon, excluding carbonates and oxides.• Catenation the covalent bonding of an element to itself to

form chains or rings.• Hydrocarbons are composed of only carbon and hydrogen;

they are the simplest organic compounds.• Compounds that have the same molecular formula but

different structures are called isomers.• Structural formula indicates the number and types of

atoms present in a molecule and also shows the bonding arrangement of the atoms.

Chapter 22 Vocabulary

• Structural isomers are isomers in which the atoms are bonded together in different orders.

• Geometric isomers are isomers in which the order of atom bonding is the same but the arrangement of atoms in space is different.

• Saturated hydrocarbons are hydrocarbons in which each carbon atom in the molecule forms four single covalent bonds with other atoms.

• Hydrocarbons that contain only single bonds are alkanes.• Cycloalkanes are alkanes in which the carbon atoms are arranged in

a ring, or cyclic, structure.• Alkyl groups are groups of atoms that are formed when one

hydrogen atom is removed from an alkane molecule• Natural gas is a fossil fuel composed primarily of alkanes containing

one to four carbon atoms• Petroleum is a complex mixture of different hydrocarbons that varies

greatly in composition.• Unsaturated hydrocarbons are hydrocarbons in which not all

carbon atoms have four single covalent bonds.

Chapter 22 Vocabulary

Chapter 22 Vocabulary

• Structural isomers are isomers in which the atoms are bonded together in different orders.

• Geometric isomers are isomers in which the order of atom bonding is the same but the arrangement of atoms in space is different.

• Alkenes are hydrocarbons that contain double covalent bonds.

• Hydrocarbons with triple covalent bonds are alkynes.• Aromatic hydrocarbons are hydrocarbons with six

membered carbon rings and delocalized electrons• Benzene is the primary aromatic hydrocarbon

Alkanes and Aromatic Hydrocarbons

Organic Compounds

Bonding in Hydrocarbons

Naming Alkanes

Properties of Alkanes

Organic Chemistry and Hydrocarbons

• _________ originally meant chemicals that came from ______________.

• 1828 German chemist Friedrich Wohler synthesized urea in a lab

• Today, organic chemistry is the chemistry of virtually all compounds containing the element ___________.

Friedrich Wohler

1800 – 1882

Used inorganic substances to synthesize urea, a carbon compound found in urine.

This re-defined organic chemistry.

Organic Chemistry and Hydrocarbons

• Over a million organic compounds, with numerous properties

• Why so many? Carbon’s unique bonding ability!

• Let’s start with the simplest of the organic compounds: Hydrocarbons

Organic Compounds

Contain _________________

Have ______________ bonds

Have low _____________ points

Have low _______________ points

Burn in air (oxygen)

Are soluble in _____________ solvents

Form large ________________

Alkanes

Contain ______ and _________ only

Contain ____________ bonds C-C

Have _____ bonds to every carbon (C) atom

Are ________________

Alkanes

Show the bonds between each of the atoms

H H

H C H H C H H H

CH4 - methane

Structural Formulas

Alkanes

H H Condensed Structural Formulas

H C C H CH3 CH3

H H Ethane

H H H

H C C C H CH3 CH2 CH3

H H H Propane

Structural Formulas

Alkanes

H H H

H C C C H

H H H

CH3 CH2 CH3

CH3CH2CH3

Structural Formulas

Structural Formula

Condensed Structural Formula

Condensed Formula

AlkanesStructural Formulas

Examples:

_____________ formula Condensed__________________

Alkanes

Organic Naming Prefixes

Naming AlkanesName # carbons Structural Formula

____ane 1 CH4

____ane 2 CH3CH3

____ane 3 CH3CH2CH3

____ane 4 CH3CH2CH2CH3

____ane 5 CH3CH2CH2CH2CH3

Naming Alkanes

Name # carbons Structural Formula

___ane 6 CH3CH2CH2CH2CH2CH3

____ane 7 CH3CH2CH2CH2CH2CH2CH3

___ane 8 CH3CH2CH2CH2CH2CH2CH2CH3

___ane 9 CH3 CH2 CH2CH2CH2CH2CH2CH2CH3

___ane 10 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3

Practice Problems

A. What is the condensed formula for H H H H

H C C C C H

H H H H

B. What is its molecular formula?C. What is its name?

Reactions of AlkanesCombustion

alkane + O2 CO2 + H2O + heat

Combustion In the Cell

Metabolic oxidation is combustion

C6H12 O6 + 6O2 6CO2 + 6H2O + heat

glucose

Combustion Example

Complete the combustion reaction for

C3H8 + O2 +

Balance your equation

Practice Problem

Complete and balance the reaction for the complete combustion of C7H16

Alkanes and Aromatic Hydrocarbons

Branched Alkanes

Structural Formulas

Alkyl Groups

Branches on carbon chains H

H C CH3 _________ H H H

H C C CH3CH2 _________ H H

Alkyl Groups

Branched Alkanes

CH3

CH3CHCH3

methyl groups

CH3 CH3

CH3CHCH2CHCH3

Naming Branched Alkanes

CH3 methyl branch

CH3CH2CH2CHCH2CH3

6 5 4 3 2 1 Count

Naming Branched Alkanes

CH3 methyl branch

CH3CH2CH2CHCH2CH3

6 5 4 3 2 1 Count

3-Methylhexane

on third C CH3 six carbon chain group

Naming Alkanes

Naming Alkanes Example

Naming Practice Problems

A. CH3 CH3

CH3CHCH2CHCH3

B. CH3 CH3

CH3CH2CHCH2CCH2CH3

CH3

Practice Problems

Write a condensed structure for

A. 3,4-dimethylheptane

B. 2,2-dimethyloctane

Isomers

• Same _____________ formula

• Same ________ and ______ of atoms

• Different ________________ of atoms

• Also have different properties, such as b.p., m.p., and reactivity

Structural Isomers

___________________ are isomers in which the atoms are bonded together in different orders.

Geometric Isomers•____________________ are isomers in which the order of atom bonding is the same but the arrangement of atoms in space is different.

Examples of Isomers

The formula C4H10 has two different structures

CH3

CH3CH2CH2CH3 CH3CHCH3

Butane 2-methylpropane

When a CH3 is is used to form a branch, it

makes a new isomer of C4H10.

Practice Problem

Write 3 isomers of C5H12 and name each.

Practice ProblemsWrite the structural formulas of 3 isomers that have the formula C5H12. Name each.

Alkanes and Aromatic Hydrocarbons

Cycloalkanes

Aromatic Hydrocarbons

Cycloalkanes

_____________ CH2

CH2 CH2

_____________CH2

CH2

CH2 CH2

More Cycloalkanes

____________ CH2

CH2 CH2

CH2 CH2

____________

CH2

CH2 CH2

CH2 CH2

CH2

Naming Cycloalkanes with Side Groups

Number of Naming

side groups

One Side group name goes in front of the cycloalkane name.

Two or moreNumber the ring in the direction that gives the lowest numbers

to the side groups.

Cycloalkanes with Side GroupsCH3

CH3

CH3

CH3

CH3

CH3

methylcyclopentane

1,2-dimethylcyclopentane

1,2,4-trimethylcyclohexane

Practice Problems

CH3

CH3

CH3

CH3

CH3

Aromatic Compounds and Benzene

___________________ contain __________.

Benzene, C6H6 , is represented as a ______

carbon ring with _____ double bonds.

Two possible can be drawn to show benzene in this form.

H

H

H

H

H

H

HH

H

H

H

H

Benzene Structure

The structures for ______________ can also be written as a single structure where the alternating double bonds are written as a circle within the ring.

Benzene

structure

Aromatic Compounds in Nature and Health

Many aromatic compounds are common in _____________ and in _____________.

COOH

COOCH3

CHO

OCH3

OH

Aspirin Vanillin

CHCOOH

CH3

CH3CHCH2

CH3

Ibuprofen

Naming Aromatic Compounds

Aromatic compounds are named with benzene as the parent chain. One side group is named in front of the name benzene.

methylbenzene chlorobenzene (toluene)

CH3 Cl

Naming Aromatic Compounds

When two groups are attached to benzene, the ring is numbered to give the lower numbers to the side groups. The prefixes ortho (1,2), meta (1,3-) and para (1,4-) are also used.

CH3

CH3

Cl

Cl

Cl

CH3

1,2-dimethylbenzene 1,3-dichlorobenzene 1-chloro-4-methylbenzene

(ortho-dimethylbenzene) (meta-dichlorobenzene) (para-chloromethylbenzene)

Some Common Names

Some substituted benzene rings also use a common name. Then naming with additional more side groups uses the ortho-, meta-, para- system.

CH3

Cl

CH3 OH

Toluene meta-chlorotoluene phenol(Methylbenzene) (meta-chloromethylbenzene) (hydroxybenzene)

Practice Problems

Write the structural formulas for each of the following:

A. 1,3-dichlorobenzene

B. Ortho-chlorotoluene

Practice Problems

Select the names for each structure:

1. Chlorocyclohexane2. Chlorobenzene3. 1-chlorobenzene

1. Meta-methyltoluene2. Meta-dimethylbenzene3. 1,3-dimethylbenzene

Cl

CH3

CH3

Haloalkanes, Alkenes, and Alkynes

Alkenes and Alkynes

Saturated and Unsaturated Compounds

Saturated compounds (alkanes) have the maximum number of hydrogen atoms attached to each carbon atom

Unsaturated compounds have fewer hydrogen atoms attached to the carbon chain than alkanes

Unsaturated compounds contain double or triple bonds alkenes & alkynes

Alkenes

Carbon-carbon _____________ bonds Names end in -___________

H2C=CH2 ethene (ethylene)

H2C=CH-CH3 propene (propylene)

cyclohexene

Alkenes

Alkynes

Carbon-carbon __________ bonds Names end in -_________

HCCH ethyne(acetylene)

HCC-CH3 propyne

Naming Alkenes and Alkynes

When the carbon chain has 4 or more C atoms, number the chain to give the lowest number to the double or triple bond.

1 2 3 4

CH2=CHCH2CH3 1-butene

CH3CH=CHCH3 2-butene

CH3CHCHCH3 2-butyne

Naming AlkenesSlide 35

Naming Alkenes

Naming Alkynes

Slide 35

Practice Problem

Write the names for each of the following unsaturated compounds:

A. CH3CH2CCCH3

CH3

B. CH3C=CHCH3 C.

CH3

Hydrogenation

Adds a hydrogen atom to each carbon atom of a double bond

H H H H

Ni

H–C=C–H + H2 H–C–C–H

H H

ethene ethane

Products of Hydrogenation

Adding H2 to vegetable oils produces

compounds with higher melting points

Margarines

Soft margarines

Shortenings (solid)

Trans Fats

In the US, it is estimated that 2-4% of our total Calories is in the form of trans fatty acid.

trans fatty acids behave like saturated fatty acids in the body.

Several studies reported that trans fatty acids raise LDL-cholesterol. Some studies also report that trans fatty acid lower HDL-cholesterol

The trans fatty acids controversy will continue to be debated.

Unsaturated Fatty Acids

Fatty acids in vegetable oils are omega-6 acids (the first double bond occurs at carbon 6 counting from the methyl group)

A common omega-6 acid is linoleic acid

CH3CH2CH2CH2CH2CH=CHCH2CH=CH(CH2)7COOH

6

linoleic acid, a fatty acid

Trans Fats

In vegetable oils, the unsaturated fats usually contain cis double bonds.

During hydrogenation, some cis double bonds are converted to trans double bonds (more stable) causing a change in the fatty acid structure

If a label states “partially” or “fully hydrogenated”, the fats contain trans fatty acids.

Fats and Atheroschlerosis

Inuit people of Alaska have a high fat diet and

high blood cholesterol levels, but a very low

occurrence of atherosclerosis and heart

attacks.

Fat in the Intuit diet was primarily from fish

such as salmon, tuna and herring rather than

from land animals (as in the American diet).

Omega-3 Fatty Acids

Fatty acids in the fish oils are mostly the omega-3 type (first double bond occurs at the third carbon counting from the methyl group).

linolenic acid 18 carbon atoms

CH3CH2CH=CHCH2CH=CHCH2CH=CH(CH2)7COOH

eicosapentaenoic acid (EPA) 20 carbon atoms

CH3CH2(CH=CHCH2)5(CH2)2COOH

Atherosclerosis

Plaques of cholesterol adhere to the walls of the

blood vessels

Blood pressure rises as blood squeezes through

smaller blood vessels

Blood clots may form

Omega-3 fatty acids decrease the “sticking” of

blood platelets (fewer blood clots)

Omega-3 fatty acids can increase bleeding time

Questions

(1) Ture or (2) False

A. ____ There are more unsaturated fats in vegetable oils.

B. ____ Vegetable oils have more omega-3 oils than found in fish.

C. ____ Hydrogenation of oils converts some cis-double bonds to trans- double bonds.

D. ____ Animal fats have more saturated fats.

Natural Gas• Fossil fuels provide much of the

world’s energy

• Natural gas and petroleum contain mostly the aliphatic (or straight-chain) hydrocarbons – formed from marine life buried in sediment of the oceans

• Natural gas is an important source of alkanes of low molecular mass

Natural Gas• Natural gas is typically:

–80% methane, 10% ethane, 4% propane, and 2% butane with the remainder being nitrogen and higher molar mass hydrocarbons

–also contains a small amount of He, and is one of it’s major sources

Natural Gas

• Natural gas is prized for combustion, because with adequate oxygen, it burns with a hot, clean blue flame:– CH4 + 2O2 CO2 + 2H2O + heat

• Incomplete burning has a yellow flame, due to glowing carbon parts, as well as making carbon monoxide

Petroleum

• The compounds found in petroleum (or crude oil) are more complex than those in natural gas

• Usually straight-chain and branched-chain alkanes, with some aromatic compounds also

• Crude oil must be refined (separated) before being used

Petroleum

• It is separated by distillation into fractions, according to boiling pt.

• Fractions containing higher molar mass can be “cracked” into more useful shorter chain components, such as gasoline and kerosene– involves catalyst and heat

– starts materials for plastics and paints

Citations• http://www.karentimberlake.com/

• http://www.cottonchemistry.bizland.com/chem/chemnotes1.htm