organic chemistry saturated & unsaturated … hydrocarbons • contain one or more double or...

Organic Chemistry

Saturated & Unsaturated

HydrocarbonsBIOB111

CHEMISTRY & BIOCHEMISTRY

Session 8

Key concepts: session 8From this session you are expected to develop an understanding of the following concepts:

Concept 1: Solubility of hydrocarbons in H2O

Concept 2: Creation of CFC compounds

Concept 3: Alkyl groups

Concept 4: Reactivity of saturated vs unsaturated hydrocarbons

Concept 5: Alkanes vs alkenes vs alkynes

Concept 6: Conversion between the hydrocarbon functional groups (alkane, alkene and alkyne)

Concept 7: Bromination reactions

Concept 8: Properties of benzene

Concept 9: Hydration reactions

Concept 10: Identifying primary, secondary and tertiary alcohols

These concepts are covered in the Conceptual multiple choice questions of tutorial 8

Session OverviewPart 1: Exploring saturated hydrocarbon compounds

• Saturated vs unsaturated hydrocarbon compounds

• Chemical properties of alkanes

• Alkyl groups are derived from alkanes

Part 2: Exploring unsaturated hydrocarbon compounds

• Chemical properties of alkenes

• Bromination reactions

• Chemical properties of alkynes

• Chemical properties of benzene

Part 3: The alcohol function group

• Hydrocarbon derivatives

• Chemical properties of alcohols

Part 1: Exploring saturated hydrocarbon compounds




Hydrocarbon derivatives

Life on earth would not exist without organic compounds that contain carbon atoms

• Our genetic material (DNA) contains many carbon atoms

• Our bodies rely on the organic compounds below to function:

– Proteins are made up of amino acids

– Lipids are often made up of fatty acids (long hydrocarbons) and glycerol

– Carbohydrates are made up of one or more monosaccharide (sugar) units

Hydrocarbon compounds:

The most basic organic compounds are hydrocarbons

– Hydrocarbons contain only carbon and hydrogen atoms

– Hydrocarbons compounds are created in nature

and can be synthesised in the laboratory

Structures of Hydrocarbon compounds

Each line connecting the atoms below represents a covalent bond (2 electrons shared between the two

connected atoms)

Saturated vs unsaturated hydrocarbon compounds

HYDROCARBONS BELONG TO ONE OF THREE

FUNCTIONAL GROUPS

Type

ALKANE

CONTAIN ONLY SINGLE CARBON

TO CARBON BONDS

ALKYNEDefinition


ALKENE

CONTAIN ONE OR MORE DOUBLE

CARBON TO CARBON BONDS

CONTAIN ONE OR MORE

TRIPLE CARBON TO CARBON

BONDS

Example

ExampleExample

Type

Type

Definition

Definition

HYDROCARBONSType

SATURATED HYDROCARBON

CONTAIN ONLY SINGLE CARBON TO

CARBON BONDS

ORGANIC COMPOUNDS THAT CONTAIN CARBON AND HYDROGEN ATOMS

CONTAIN ONE OR MORE DOUBLE OR TRIPLE CARBON TO CARBON BOND,

ALSO CONTAIN ONE OR MORE SINGLE CARBON TO CARBON BONDS

UNSATURATED HYDROCARBON

Type

Definition

Definition

Definition

UNREACTIVE

Are

REACTIVE

Are

Due to

LARGE AMOUNT OF ENERGY NEEDED TO BREAK THE SINGLE BONDS PRESENT

Due to

DOUBLE AND TRIPLE CARBON TO CARBON BONDS CAN EASILY BE

BROKEN IN A CHEMICAL REACTION


Unsaturated hydrocarbons• Contain one or more double or

triple carbon to carbon bond– Are also likely to contain one or

more single carbon to carbon bonds

• Functional groups: Alkene, alkyne

Saturated hydrocarbons

• Contain only single carbon to carbon bonds

• Functional groups: Alkane

• Unreactive and stable– Due to the large amount of energy

needed to break the existing chemical

bonds

• Reactive and unstable (compared

to saturated hydrocarbons)– Due to the small amount of energy

required to break the double or triple

carbon to carbon bonds present


Saturated Hydrocarbons

– Saturated hydrocarbons have only single carbon to carbon bonds


– The carbon atoms in saturated hydrocarbons form bonds to the

maximum amount of hydrogen atoms possible

• These compounds are saturated with hydrogen atoms

– Include alkanes (straight chains) & cycloalkanes (carbon rings)

Unsaturated Hydrocarbons– Unsaturated hydrocarbons have one or more double or triple

carbon to carbon bond(s)• Will also contain single carbon to carbon bonds


– The carbon atoms in unsaturated hydrocarbons form bonds to less than the maximum amount of hydrogen atoms possible

• These compounds are not saturated with hydrogen atoms (unsaturated)– Due to the presence of double or triple carbon to carbon bonds

– Include Alkenes (straight chains) & Cycloalkenes (carbon rings)

Number of Carbon Atoms Prefix Alkane Alkene Alkyne

1 Meth- Methane - -

2 Eth- Ethane Ethene Ethyne

3 Prop- Propane Propene Propyne

4 But- Butane Butene Butyne

5 Pent- Pentane Pentene Pentyne

6 Hex- Hexane Hexene Hexyne

7 Hept- Heptane Heptene Heptyne

8 Oct- Octane Octene Octyne

9 Non- Nonane Nonene Nonyne

10 Dec- Decane Decene Decyne


Chemical properties of alkanesPropane is an alkane:

Used as a fuel for cars

(LPG gas)

Functional Group: Alkane

Distinguishing characteristic: Alkane compounds contain only single

carbon to carbon bonds

Naming convention: Alkane compounds have –ane at the end of their

name e.g. propane

Example compound:

Propane


FUNCTIONAL GROUPS

Type

ALKANE


TO CARBON BONDS

ALKYNEDefinition

Chemical properties of alkanes

ALKENE



CONTAIN ONE OR MORE


BONDS

Example

ExampleExample

Type

Type

Definition

Definition


Alkanes are non-polar compounds

– Alkanes contain only carbon and hydrogen atoms which are connected via non-polar covalent bonds (equal electron sharing)

H2O is a polar compound

– H2O contains polar covalent bonds where the shared electrons are more attracted to the oxygen atom than the hydrogen atoms

• Compounds must be polar to dissolve in H2O


Will an alkane compound (such as propane) dissolve in H2O?

– Non-polar alkanes do not dissolve in polar H2O

– Alkanes are insoluble in H2O

– The non-polar alkane will only dissolve in non-polar solvents such as chloroform

Propane

Chemical properties of alkanesCombustion– Combustion reactions are exothermic

reactions that release heat

– Alkanes burn in the presence of oxygenproducing CO2, H2O and heat via combustion reactions

– Example: combustion of methane

CH4 + 2O2 → CO2 + 2H2O + Energy

https://www.freeimages.com/photo/fire-camp-1174281

– All combustion reactions are redox

reactions where one reactant is oxidised

and one is reduced

• Oxygen is always reduced

in redox reactions


Halogenation

– Halogenation reactions involve an alkane reacting with

a halogen molecule such as Cl2 or F2

– The end result of a halogenation reaction:

• Substitution of one of the alkane’s hydrogen atoms with a halogen

atom, producing a halogenated alkane

Stoker 2014, p368-70

Methane Halogen molecule

Halogenated alkane

C Cl

H

H

H

H Cl C

H

H

H

Cl H Cl+ +Methane

Halogen molecule

Halogenated alkane

• During a halogenation reaction the alkane’s hydrogen atom is replaced by

a single halogen atom, producing a halogenated alkane

• The lost hydrogen atom forms a compound with the other halogen atom (from the

halogen molecule), in this case creating the strong acid HCl

• Additional hydrogen atoms can be substituted in the halogenated alkane by performing

additional halogenation reactions

Large energy input

Halogenation

C Cl

H

H

H

H Cl+MethaneReactant

Halogen moleculeReactant

Halogenated alkane

HCl product

Animation of a halogenation reaction


Energy input Energy

input


Chlorofluorocarbons (CFCs)– Synthetic organic compounds that were developed to be used as refrigerants

• Refrigerants can be used to heat a pump that powers refrigeration

– The 2 most commonly used CFCs were Freon-11 and Freon-12

• CFCs destroyed a significant amount of the ozone layer in the stratosphere until banned

Stoker 2014, p373

How many halogenation reactions would it take to

convert methane (CH4) into a halogenated alkane

that contains three fluorine atoms?

Alkyl groups are derived from alkanes

Alkyl Groups

– Once an alkane loses one of its hydrogen atoms

it becomes an alkyl group

Alkane: methane Alkyl group: methyl

Alkane loses a hydrogen atom

• Naming: replace the -ane with -yl at the end of the name

– Methane becomes methyl

Alkyl groups are derived from alkanesAlkyl Groups

– Once an alkane loses one of its hydrogen atoms it becomes an alkyl group

– Alkyl groups can attach to an atom or compound

by forming a covalent bond

Alkyl group: methyl

R represents an attachment point to another atom or

compound

Methyl Group

Methyl group branching off a 5 carbon chain

Alkyl groups: derived from alkanes

Ethyl Group

Ethyl group branching off a 5

carbon chain

After methane loses a hydrogen = methyl group R—CH3

After ethane loses a hydrogen = ethyl group R—CH2—CH3

After propane loses a hydrogen = propyl group R—CH2—CH2—CH3

Identify the name and position of the alkyl group in

the compound below

Attempt Socrative questions: 1 to 3

Google Socrative and go to the student login

Room name:

City name followed by 1 or 2 (e.g. PERTH1)

1 for 1st session of the week and 2 for 2nd session of the week



– Saturated hydrocarbons contain only single carbon to carbon bonds and

contain the maximum number of hydrogen atoms attached to the carbon

atoms

– Alkanes and cycloalkane are saturated hydrocarbons

– Unsaturated hydrocarbons contain one or more double or triple carbon to

carbon bonds, as well as other single carbon to carbon bonds

– Unsaturated hydrocarbons contain less than the maximum number of

hydrogen atoms attached to the carbon atoms, due to the presence of double

or triple carbon to carbon bonds

– Alkenes and cycloalkenes are unsaturated hydrocarbons



– Alkanes are non-polar compounds that do not dissolve in H2O (insoluble in

H2O)

– Alkanes burn in oxygen in combustion reactions (type of redox reaction)

– Alkanes can react with halogen molecules (e.g. Cl2) to replace one hydrogen

at a time with a halogen atom via a halogenation reaction


– Once an alkane loses one of its hydrogen atoms it becomes an alkyl group

– Alkyl groups can attach to an atom or compound by forming a covalent bond

– Methane becomes a methyl group by losing a hydrogen atom


• Chemical properties of alkenes




Chemical properties of alkenes

Functional Group: Alkene

Distinguishing characteristic: Alkene compounds contain one or more

double carbon to carbon bond(s), and will also likely contain some single


Naming convention: Alkene compounds have -ene at the end of their

name e.g. propene

Example compound:

Propene


FUNCTIONAL GROUPS

Type

ALKANE


TO CARBON BONDS

ALKYNEDefinition


ALKENE



CONTAIN ONE OR MORE


BONDS

Example

ExampleExample

Type

Type

Definition

Definition

Stereoisomers are a group of two compounds that are very similar:

• The group of compounds has the same number of each type of atom present and the same

chemical bonding pattern

• Each of the two stereoisomer compounds are arranged differently in space

– The two different variations of the stereoisomer compounds

have different chemical properties

– Example:

• cis stereoisomer = both large CH3 groups are on the same side of the carbon to carbon double bond

• Trans stereoisomer = The large CH3 groups are on different sides of the carbon to carbon double bond

cis = same trans = different


The stereoisomer

pair to the right are alkenes

• Unsaturated hydrocarbons (such as alkenes and alkynes)

are more reactive than saturated hydrocarbons (such as alkanes)


Each line represents a single covalent bond that requires significant input

energy to break

– Alkanes contain only single carbon to carbon bonds, which require

significant input energy to break

• Difficult to replace hydrogen atoms attached to carbons with other

atoms (e.g. halogens Cl, F)

– Alkanes stable and unreactive

• Unsaturated hydrocarbons (such as alkenes and alkynes) are more

reactive than saturated hydrocarbons (such as alkanes)

– Alkenes and alkynes have double and triple carbon to carbon bonds, respectively


Multiple carbon to carbon bonds which can be broken with a

small amount of input energy

– A double or triple carbon to carbon bond can be broken with a smaller amount of input energy than single carbon to carbon bond

– Once a double or triple carbon to carbon bond has been broken:• Other atoms can bond to the carbon atoms that were previously part

of the multiple carbon to carbon bond– Carbon must have 4 covalent bonds at all times to be stable


C C CH

H

HH

H

H

Cl Cl+Energy input

Energy input

Once the double carbon to carbon bond is broken the two chlorine atoms are incorporated into the compound, which allows each carbon atom to have 4 covalent bonds

Animation of the reactivity of an alkene

Addition Reaction Reactants Products

HYDROGENATION Alkene + H2 Alkane

HALOGENATION Alkene + Cl2 or Br2 Halogenated alkane

HYDRATION Alkene + H2O Alcohol

• Alkenes can take part in addition reactions:

– Once a double or triple carbon to carbon bond has been broken:• Other atoms can bond to the carbon atoms that were previously part

of the multiple carbon to carbon bond– Carbon must have 4 covalent bonds at all times to be stable

• Breaking a multiple carbon to carbon bond creates new positions where carbon atoms can form covalent bonds to other atoms


Addition of a H2 molecule into an alkene:

• Replaces the double carbon to carbon bond with two new covalent bonds between

the carbon atoms and the added hydrogen atoms

– End result: the alkene is converted to an alkane

• The carbon atoms that form the new bonds with the added hydrogen atoms

were previously part of the double carbon to carbon bond


Propene (alkene) Hydrogenmolecule

Propane (alkane)

Hydrogenation reaction


C C CH

H

HH

H

H

H H+Energy input

Energy input

Once the double carbon to carbon bond is broken the two hydrogen atoms are incorporated into the compound, which allows each carbon atom to have 4 covalent bonds

Animation of a hydrogenation reaction where an alkene is converted into an alkane

Hydration reaction


Propene (alkene) watermolecule

Propanol (alcohol)

Alcohol functional group

Addition of a H2O molecule into an alkene:


one carbon atom and H, a second carbon atoms and an OH group

– End result: the alkene is converted to an alcohol (contains the alcohol functional group)

• The carbon atoms that form the new bonds with the H and OH



C C CH

H

HH

H

H

OH H+Energy input

Energy input

Once the double carbon to carbon bond is broken the OH group and a hydrogen atom are incorporated into the compound, which allows each carbon atom to have 4 covalent bonds

Animation of a hydration reaction where an alkene is converted into an alcohol

H2O


Halogenation reaction


Propene (alkene) Halogenmolecule

Halogenated alkane

Addition of a halogen molecule (e.g. Cl2) into an alkene:


the carbon atoms and the added halogen atoms

– End result: the alkene is converted to a halogenated alkane

• The carbon atoms that form the new bonds with the added halogen atoms were previously part of the double carbon to carbon bond

• Each halogenation reaction with an alkene adds two halogen atoms at a time


C C CH

H

HH

H

H

Cl Cl+Energy input

Energy input

Once the double carbon to carbon bond is broken the two chlorine atoms are incorporated into the compound, which allows each carbon atom to have 4 covalent bonds

Animation of a halogenation reaction where an alkene is converted into a halogenated alkane

• Bromine is a halogen (Br2) that can readily be added into an alkene via a halogenation reaction

• A large amount of input energy is needed to add bromine atoms into an alkane

one at a time via a halogenation reaction, so the reaction occurs less often

Propene (alkene) Halogenmolecule

Halogenated alkane

Propane (alkane) Halogenmolecule

Halogenated alkane

Large energy input

Reactive

Less reactive

Bromination reactions

• A Bromination test is used to determine whether a solution contains a dissolved alkane or alkene

– When in solution, bromine is red

– When bromine is incorporated into a compound

the solution becomes colourless

Stoker 2014, p399

The red colour shows that bromine is in the solution

Once all of the bromine is incorporated into a compound,

the solution is colourless


What will happen when bromine is added to an alkane solution?

– When bromine (Br2) is added to an alkane solution,

the red color of bromine persists• Br2 is not incorporated into the alkane compound

• No chemical reaction occurs due to large amount of energy needed to begin the reaction

The red bromine is not incorporated into the alkane

compound

The red colour remains as bromine has not been incorporated into a

compound Stoker 2014, p399


What will happen when bromine is added to an alkene solution?

– When bromine (Br2) is added to an alkene or alkyne solution, the red color of bromine disappears quickly

• Br2 is readily incorporated into the alkene compound, which becomes a halogenated alkane via a halogenation reaction

Bromine is readily incorporated into

the alkene compound

Once all of the bromine is incorporated into a compound,

the solutions is colourless Stoker 2014, p399

Chemical properties of alkynes

Functional Group: Alkyne

Distinguishing characteristic: Alkyne compounds contain one or more

triple carbon to carbon bond(s), and will also likely contain some single


Naming convention: Alkyne compounds have –yne at the end of their

name e.g. propyne

Example compound:

Propyne

HYDROCARBONS WHICH CONTAIN ONLY

CARBON AND HYDROGEN ATOMS BELONG TO

ONE OF THREE FUNCTIONAL GROUPS

Type

ALKANE


TO CARBON BONDS

ALKYNEDefinition


ALKENE



CONTAIN ONE OR MORE


BONDS

Example

ExampleExample

Type

Type

Definition

Definition


• Alkynes can participate in many of the same chemical reactions as alkenes:

– Hydrogenation • Adding two hydrogen atoms

– Hydration• Adding H2O, which creates an alcohol group

– Halogenation reactions• Adding two halogen atoms

• Alkynes behave similarly to alkenes in chemical reactions

– Both have multiple carbon to carbon bonds which can be broken with a small energy input


Which addition reaction could be used to convert

and alkyne into an alkane? – How many of these addition reactions would be required?

• Two hydrogenation reactions are required to

convert an alkyne into an alkane

– Each hydrogenation reaction adds two hydrogen atoms to the compound

Propene (alkene) Propane (alkane)Propyne (alkyne)

Hydrogenation Hydrogenation

+ 2 hydrogen atoms

+ 2 hydrogen atoms


C C CH

HH H H H+

Energy input

Energy input

Once the triple carbon to carbon bond is broken, two hydrogen atoms are incorporated into the compound, which allows each carbon atom to have 4 covalent bondsThe alkyne has been converted into an alkene

Animation of the two hydrogenation reactions required to convert an alkyne into an alkane

Energy input

H HEnergy input+

Once the double carbon to carbon bond is broken, two hydrogen atoms are incorporated into the compound, which allows each carbon atom to have 4 covalent bondsThe alkene has been converted into an alkane

Are saturated or unsaturated hydrocarbons

more reactive?

What types of chemical reactions do the

reactive hydrocarbons participate in?

What allows the reactive hydrocarbons

to participate in these reactions?

How is an alkyne converted to alkane?

Does the alkyne compound become more or less stable

through the conversion to an alkane? Why?

Key concept: bonding arrangements of hydrocarbons

Attempt Socrative questions: 4 to 8


Room name:



Chemical properties of benzene

• Aromatic hydrocarbons contain the benzene ring

• Benzene is a unique compound due to the behaviour of its carbon to carbon bonds

Representations of benzene:

Aromatic compound:Benzene is toxic to

liver cells (can cause liver cell death)


• When benzene was discovered scientists were puzzled – Benezene had multiple double carbon to carbon bonds but was stable

• Benzene behaved more like an alkane than an alkene or alkyne

• Benzene continually switches between two forms where the positions of the double and single carbon to carbon bonds alternate– The two forms of benzene are called resonance structures

Resonance structure 1 Resonance structure 2


Animation of the benzene ring switching between it’s resonance structures

Chemical properties of benzeneIn the benzene ring:– Every carbon atom is attached to two other carbon atoms

by at least one carbon to carbon bond

– 3 extra carbon to carbon bonds in the benzene ring are formed by 6 electrons (2 electrons for each bond)

• The extra bonds alternate their positions (see the resonance structures below)

Chemical properties of benzeneIn the benzene ring:

• The 6 electrons within the three extra carbon to carbon bonds are equally shared between all 6 carbons in the ring, as the extra bonds continually change position

– The extra carbon to carbon bonds changing position makes it difficult to break them via addition reactions, which makes benzene very stable

– Benzene is much more stable than other unsaturated hydrocarbons, which have static multiple carbon to carbon bonds like alkenes and alkynes

How is benzene different to other hydrocarbons

such as alkanes, alkenes and alkynes?

What are resonance structures of benzene and

how do they explain the stability of benzene?

Would it be easier to break a double carbon to carbon bond

within an alkene or in benzene? Justify your answer.

G

Key concept: hydrocarbon functional groups

Attempt Socrative questions: 9 and 10


Room name:




• Chemical properties of alkenes– Alkenes contain a double carbon to carbon bond, which makes the alkene compound

more reactive than an alkane compound

– The double carbon to carbon bond in an alkene can be broken with a small energy input

– Once a double carbon to carbon bond has been broken, other atoms can bond to the carbon atoms (that were previously part of the multiple carbon to carbon bond) to ensure that each carbon forms 4 covalent bonds

– Hydrogenation reactions involve breaking the double bond within an alkene compound and replacing the double bond with two new bonds to two hydrogen atoms

• Hydrogenation reactions convert alkenes into alkanes

– Hydration reactions involve breaking the double bond within an alkene compound and replacing the double bond with two new bonds to one hydrogen atom and one OH group

• Hydration reactions convert alkenes into alcohols

– Halogenation reactions involve breaking the double bond within an alkene compound and replacing the double bond with two new bonds to two halogen atoms (e.g. chlorine or fluorine)

• Halogenation reactions convert alkenes into halogenated alkanes



– Bromine readily reacts with an alkene solution to be incorporated into a new compound, so the red bromine solution becomes colourless as the bromine is taken up into the compound

– Bromine does not react readily with an alkane solution, so the red bromine solution remains red


– Alkynes behave similarly to alkenes in chemical reactions

– Both alkynes and alkenes have multiple carbon to carbon bonds which can be broken with a small amount of input energy

– Alkynes can participate in hydrogenation, hydration and halogenation reactions (just like alkenes) to replace multiple carbon to carbon bonds with new bonds to other atoms



– Benzene continually switches between two forms, called resonance

structures, where the positions of the double and single carbon to carbon

bonds alternate

– Within benzene, the 6 electrons in the three extra carbon to carbon bonds are

equally shared by all 6 carbons in the ring, as the bonds continually change

position

– The movement of the double carbon to carbon bonds within benzene makes it

difficult to break the bonds via addition reactions, which makes benzene very

stable

Part 3: The alcohol function group

• Hydrocarbon derivatives

• Chemical properties of alcohols


Hydrocarbon derivatives are:

• Hydrocarbon compounds that contain atoms such as oxygen, nitrogen, fluorine or chlorine as well as carbon and hydrogen atoms

– The location within the hydrocarbon derivative that has atoms other than just carbon and hydrogen is where the functional group is located

Ethanol: present in alcoholic beverages

Alcohol

What are functional groups?– A functional group is a group of atoms within a compound that provides chemical reactivity

• The functional group is usually the part of the compound that is involved in chemical reactions

• All compounds with a particular functional group will behave similarly in chemical reactions

– To find a functional group within a compound,

look for atoms other than just carbon and hydrogen atoms

Alcohol


Ethanol: present in alcoholic beverages

Chemical properties of alcohols

Functional Group: Alcohol

Functional group formula:

Naming convention: Alcohol compounds have –ol at the end of the name

e.g. ethanol

Example compound:

Propanol

R OHThe alcohol functional group is also

known as the hydroxyl group

The alcohol functional group is located at the

end of a compound (or a branch point), as it

contains one R-group

Alcohol

Functional group

PRIMARY (1°) ALCOHOL

THE CARBON BONDED TO THE ALCOHOL

FUNCTIONAL GROUP IS BONDED TO ONE

OTHER CARBON ATOM

Definition SECONDARY (2°) ALCOHOL


FUNCTIONAL GROUP IS BONDED TO TWO

OTHER CARBON ATOMS


FUNCTIONAL GROUP IS BONDED TO THREE

OTHER CARBON ATOMS

Type

TypeType

Definition

Example

Example

TERTIARY (3°) ALCOHOL

Example

Definition


How to work out whether an alcohol is 1°, 2° or 3°:

The compound has two carbons attached to the carbon bonded

to the alcohol functional group = secondary alcohol

– Step 1: Identify the carbon that is directly bonded to the alcohol functional group

– Step 2: Count the number of carbon atoms attached to the carbon identified in step 1

– Step 3: The number of attached carbons identified in step 2

specifies whether it is a primary, secondary or tertiary alcohol

• 1 attached carbon = 1° Alcohol



Classify the following compounds

as either a 1°, 2° or 3° alcohols:

1.

2.

3.

4.

Chemical properties of alcoholsCombustion– Combustion reactions are exothermic reactions that

release heat

– Alcohols burn in the presence of oxygen producing CO2, H2O and heat via combustion reactions

– Example: combustion of ethanol

C2H6O + 3O2 → 2CO2 + 3H2O + Energy

– All combustion reactions are redox reactions where one reactant is oxidised and one is reduced

• Oxygen is always reduced in redox reactions

https://www.freeimages.com/photo/hell-of-a-drink-1218762


Alcohol compound Alkene compound + H2O

Dehydration (removal of H2O)

Hydration (addition of H2O)

Hydration reaction


Propene (alkene) watermolecule

Propanol (alcohol)


Addition of a H2O molecule into an alkene:


the carbon atoms and a H and an OH

– End result: the alkene is converted to an alcohol (contains the alcohol functional group)

• The carbon atoms that form the new bonds with the H and OH



C C CH

H

HH

H

H

OH H+Energy input

Energy input

Once the double carbon to carbon bond is broken the OH group and a hydrogen atom are incorporated into the compound, which allows each carbon atom to have 4 covalent bonds

Animation of a hydration reaction where an alkene is converted into an alcohol

H2O


Dehydration reaction:


Propene (alkene)Propanol (alcohol)


watermolecule

Removal of a H2O molecule from an alcohol:• The bonds to the OH and H within the compound are broken, allowing an extra

carbon to carbon bond to form, which creates a double carbon to carbon bond

– End result: the alcohol is converted into an alkene

• The carbon atoms that lost the bonds to H and OH are the carbon atoms that form the double carbon to carbon bond

• The OH and H that are released from the compound come together to form a H2O molecule


C C CH

H

HH

H

H

OH H

+

Once the bonds connecting OH and H to the carbon atoms break, the OH and H come together to form H2O and the carbon atoms form an additional carbon to carbon bond, which allows each carbon atom to have 4 covalent bonds

Animation of a dehydration reaction where an alcohol is converted into an alkene

H2O


Attempt Socrative questions: 11 and 12


Room name:



Part 3: The alcohol function group• Hydrocarbon derivatives

– Hydrocarbon derivatives are compounds that contain atoms such as oxygen,

nitrogen, fluorine or chlorine as well as carbon and hydrogen atoms

• Chemical properties of alcohols– The alcohol functional group is located at the end of a compound (or a branch point), as it contains

one R-group

– The number of carbons attached to the carbon that is bonded to the alcohol group specifies whether the alcohol is primary, secondary or tertiary:




– Alcohols burn in oxygen via combustion reactions (a type of redox reaction)

– Hydration reactions involve breaking the double bond within an alkene compound and replacing the double bond with new bonds to one hydrogen atom and one OH group

• Hydration reactions convert alkenes into alcohols

– Dehydration reactions involve the removal of a H2O molecule from an alcohol, where the bonds to the OH and H that make up H2O are replaced by a extra carbon to carbon bond (creates a double carbon to carbon double bond in the compound)

• Dehydration reactions convert alcohols into alkenes

Readings & Resources• Stoker, HS 2014, General, Organic and Biological Chemistry, 7th edn,

Brooks/Cole, Cengage Learning, Belmont, CA.

• Stoker, HS 2004, General, Organic and Biological Chemistry, 3rd edn, Houghton Mifflin, Boston, MA.

• Timberlake, KC 2014, General, organic, and biological chemistry: structures of life, 4th edn, Pearson, Boston, MA.

• Alberts, B, Johnson, A, Lewis, J, Raff, M, Roberts, K & Walter P 2008, Molecular biology of the cell, 5th edn, Garland Science, New York.

• Berg, JM, Tymoczko, JL & Stryer, L 2012, Biochemistry, 7th edn, W.H. Freeman, New York.

• Dominiczak, MH 2007, Flesh and bones of metabolism, Elsevier Mosby, Edinburgh.

• Tortora, GJ & Derrickson, B 2014, Principles of Anatomy and Physiology, 14th edn, John Wiley & Sons, Hoboken, NJ.

• Tortora, GJ & Grabowski, SR 2003, Principles of Anatomy and Physiology, 10th edn, John Wiley & Sons, New York, NY.

organic chemistry saturated & unsaturated … hydrocarbons • contain one or more double or...

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