Chapter 22 Carbon & Hydrocarbons
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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
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