Transcript Organic Chemistry IB Organic Chemistry 2016x

IB Organic Chemistry
Organic – What is it?
• Originally defined as the chemistry
of all living things
• Now defined as the chemistry of carbon and
its compounds
– Includes
• All biological molecules
• Fossil fuels
• Most synthetic materials
– plastics
Homologous Series
• There are so many organic molecules that we
need a classification system
• Homologous series : a family of like organic
molecules
– Members of the series have differing numbers of
carbon atoms
– Have similar characteristics and functional
groups
Series: Alkanes
•
•
•
•
Carbon chains that have only single bonds
Saturated hydrocarbons
CH4
Methane
Name ends in -ane
C2H6
Ethane
CnH2n+2
C3H8
Propane
C4H10
Butane
C5H12
Pentane
Naming: IUPAC
• International Union of Pure and Applied Chemistry
• Rule 1: Identify the
longest straight or
continuous chain of
carbon atoms
•This identifies the
stem or root of the
name
Number of
Carbons
Stem for
IUPAC name
1
2
3
4
5
6
methethpropbutpenthex-
Examples
Naming: IUPAC
Type
Alkane
Alkene
Alkyne
suffix
-ane
-ene
-yne
• Rule 2: add a
suffix based on
the type of chain
The location
of the double
or triple
bonds need to
be specified
Examples
Naming: IUPAC
• Rule 3: Name
the side chains as
the prefix of the
name (label the
carbon that it is
located on)
Number of
Carbons
Branch
name
1
2
3
4
5
6
methylethylpropylbutylpentylhexyl-
Examples
Series: Alkenes
•
•
•
•
Carbon chains that contain a double bond
Unsaturated hydrocarbons
Name ends in -ene
C2H4
Ethene
CnH2n
C3H6
Propene
C4H8
1-Butene
C5H10
1-Pentene
Series: Alkynes
•
•
•
•
Carbon chains that contain a triple bond
Unsaturated hydrocarbons
Name ends in -yne
C2H2
Ethyne
CnH2n-2
C3H4
Propyne
C4H6
1-Butyne
C5H8
1-Pentyne
Functional Groups
• Groups attached to the carbon framework
that give the molecule certain characteristics
Series: Alcohols
• Functional Group: hydroxyl group, -OH
• Name ends in -ol
CH3OH
Methanol
CH3CH2OH
Ethanol
CH3CH2CH2OH
1-Propanol
Series: Carboxylic acids
• Functional Group: carboxyl group, -COOH
• Name ends in –oic acid
No numbers needed!
HCOOH
Methanoic acid
CH3COOH
Ethanoic acid
CH3CH2COOH Propanoic acid
Series: Aldehyde
• Functional Group: carbonyl group
• Name ends in -al
No numbers needed!
H
CH2O
Methanal
CH3CHO
Ethanal
CH3CH2CHO
Propanal
Series: Ketone
• Functional Group: carbonyl group
• Name ends in -one
Numbers needed when > 4 carbons
CH3COCH3
Propanone
CH3COCH2CH3
Butanone
Series: Esters
• Functional Group: -COOR
• Name ends in –oate
Propyl ethanoate
CH3COOCH3
Methyl ethanoate
CH3COOCH2CH3
Ethyl ethanoate
CH3CH2COOCH3
Methyl propanoate
CH3CH2COOCH2CH3
Ethyl propanoate
Series: Halides
• Functional Group: presence of halogen
• Name – suffix stays the same
CH3CH2CH2Cl 1-chloropropane
• Empirical
Types of Formulas
(simplest ratio)
• Molecular
• Full Structural
• Condensed Structural
• Line formula
Naming: IUPAC
• International Union of Pure and Applied Chemistry
• Rule 1: Identify the
longest straight or
continuous chain of
carbon atoms
•This identifies the
stem of the name
Number of
Carbons
Stem for
IUPAC name
1
2
3
4
5
6
methethpropbutpenthex-
Naming: IUPAC
• Rule 2: Use the functional group ending as
the suffix of the name (-ane, -ene, -yne, ol, -al, -one, -oic acid, -oate)
• Rule 3: Name
the side chains as
the prefix of the
name (label the
carbon that it is
located on)
Side chain
-CH3
Prefix
methyl
-C2H5
-C3H7
-F, -Br, -I, -Cl
ethyl
propyl
fluoro-, chloro-,
iodo-, bromo-
-NH2
-OH
aminohydroxy-
ID ONLY
• CH3-O-CH2-CH3
• CH3—CH2—NH2
methoxyethane (ether)
ethylamine
(amine)
• CH3—CH2—C—NH2 Propanamide (amide)
O
Review Activity
• Part I
– Come up with 10 names and 10 structures….
– Place them in random order
• Part II
– Switch papers with someone else and solve
• Part III
– Check each others answers
– Check another group’s answers if time…
Rings
• Add the word cyclo- to the stem
• Examples
– cyclopropane
– cyclobutane
– cyclopentane
– cyclohexane
Aromatic Molecules
• Contain the benzene ring
• Unsaturated cyclohexene
Isomers
• Molecules that have the same kinds and
numbers of atoms, but different arrangements
2-methylpropane
CH3CHCH3
CH3
butane
CH3CH2CH2CH3
Cis-Trans Isomers
•
•
•
•
Alkenes
Rotation at c-c double bonds restricted
cis = same side of double bond
trans = opposite sides
Primary, Secondary, & Tertiary
• Primary carbon atoms: attached to
functional group and 1 other carbon
• Secondary carbon atoms: attached to the
functional group and 2 carbons
• Tertiary carbon atoms: attached to
functional group and 3 other carbons
Activity
1. Determine the
strongest IMF
present for:
– Alcohols
– halides
– Ketones
– Aldehydes
– C. acids
– alkanes
2. Determine the
polarity.
(high/medium/lo
w)
3. Cut out and
arrange your
pieces by physical
properties…
Physical Properties
• Boiling point: As the carbon chain lengthens,
the boiling point increases
• Solubility:
– Length of hydrocarbon chain:
• chains are nonpolar
• Solubility decreases as chain increases
– Functional group: ability to form hydrogen
bonds and interact with water
• Alcohols, aldehydes, ketones, and carboxylic acids
soluble
• Halogenalkanes are not soluble in water
Halogenoalkanes…
• Very slightly soluble in water.
• Only slightly polar
• Do not effectively break the hydrogen bonds between
water molecules.
• Soluble in nonpolar or less polar organic solvents such as
alcohol and benzene .
Physical Properties
• Volatility: ease of changing
into the gaseous state
1.
Chain length:
•
•
•
As the chain increases, the boiling point increases:
Smaller chains likely to be gases or liquids
Larger chains likely to be solids
Physical Properties
• Volatility
2. Branching of the chain:
•
more branches = more space around the
molecule = weaker IMFs = lower boiling points
3. Functional groups:
•
Polar groups have higher boiling points- stronger
intermolecular forces- harder to break apart
Most
volatile
Least
volatile
Increasing boiling points
Increasing strength of intermolecular attraction
Alkane Reactivity
• Low reactivity!
C-C and C-H bonds are very strong
• Combustion
– Complete produces carbon dioxide and water
– Incomplete  limited oxygen – new products
formed
Carbon monoxide (limited oxygen)
Carbon (extremely limited oxygen)
Alkane Combustion
• Carbon dioxide – greenhouse gas
• Water – greenhouse gas
(absorb radiation and contribute to global warming)
• Carbon monoxide – toxic to us
(absorbed by the body and bonds to hemoglobin
preventing oxygen from being carried)
• Carbon – particulates formed in the air, and
is harmful to respiratory system
Alkane Reactivity
• Substitution reactions – main type of
reaction alkanes undergo
– An incoming species takes the place of a H atom
– Often called free radical substitutions
Cl2 + CH4  CH3Cl + HCl
Three Basic Steps in a
Free Radical Mechanism
1. Chain initiationThe chain is initiated by UV light breaking a chlorine
molecule into free radicals.
Cl2  2Cl.
39
Homolytic Fission
• Free radicals are formed if a bond splits
evenly - each atom getting one of the two
electrons. The name given to this is
homolytic fission.
40
Three Basic Steps in a
Free Radical Mechanism
2. Chain propagation reactions-
These are the reactions which keep the chain going
Have to have free radicals in the system to keep
the chain going
CH4 + Cl.  CH3. + HCl
CH3. + Cl2  CH3Cl + Cl .
41
Three Basic Steps in a
Free Radical Mechanism
3. Chain termination reactions
These are reactions which remove free radicals
from the system without replacing them by new
ones – terminating the rxn
2 Cl.  Cl2
CH3. + Cl.  CH3Cl
CH3. + CH3.  CH3CH3
42
Alkene Addition Rxns
• Moves from unsaturated to saturated
• Hydrogenation – addition of hydrogen on
the double bond
– Margarine is solid at room temperature because
it has been hydrogenated and is saturated
(higher melting points)
Alkene Addition Rxns
• Halogenation: occur at room temperature
– Accompanied by the loss of color of the reacting
halogen
Alkene Addition Rxns
• Hydrohalogenation: occur at room
temperature
Alkene Addition Rxns
• Hydration
– Addition of water turns the alkene into an
alcohol
Water splits into H and OH
Markovnikov’s Rule
• Hydrogens add to the carbon that has the
most hydrogens already!
Polymers
• Types of synthetic and natural polymers.
Polymerization of Alkenes
• Alkene acts as the monomer (building block
of a polymer)
• Plastics are polymers of alkenes
polyethene
polypropene
Polymerization of Alkenes -PVC
• Polymerization of chloroethene into
polychloroethene
– aka: PVC (polyvinylchloride)
Polymer Recycling Codes
Common household polymers
Polymers
• The number code indicates the polymer type
Alcohols
• Increased solubility in water
• CnH2n+1OH
• Oxidation:
– Complete oxidation: combustion reactions
2CH3OH(l) + 3O2(g) 2CO2(g) + 4H2O(g)
Alcohols
• O and heat can be added to oxidize the OH
group (in the form of Potassium dichromate VI)
• Primary alcohols-oxidized to carboxylic acids
• 2ndary alcohols- oxidized to ketones
• Tertiary alcohols- NR
Oxidation
• Alcohols are oxidized to alkanals (aldehydes) or alkanones
(ketones)
Oxidation: Primary Alcohols
• Ethanol is oxidized to ethanal
Oxidizing agent:
Potassium dichromate VI
• Can be further oxidized to ethanoic acid
• Wine left exposed to air starts to smell of vinegar – this is
the ethanoic acid
Oxidation: Secondary Alcohols
• Propanol oxidized to propanone
Oxidation: Tertiary Alcohols
• There is no hydrogen attached to the tertiary carbon. It is
not possible for the tertiary acid to have a carbonyl group
attached.
Primary Halogenoalkanes
SN2 Mechanism
• Substitution nucleophilic bimolecular
• Bimolecular: depends on the concentration
of both reactants (halogenoalkane and –OH)
Tertiary Halogenoalkanes
SN1 Mechanism
• Substitution nucleophilic unimolecular
• Depends only on the concentration of the
halogenoalkane
• Steric hindrance caused by three alkyl groups
around carbon
– Bulky groups makes it difficult for an incoming
group to attack the carbon atom
Tertiary Halogenoalkanes
SN1 Mechanism
• Both reactions involve heterolytic fission of
C-Cl bond
Secondary Halogenoalkanes
mechanisms
• Secondary halogenoalkanes undergo a
mixtures of SN1 and SN2 reactions, depending
on reaction conditions
M&D questions
• The structures of morphine and diamorphine
(heroin) are shown in Table 20 of the Data
Booklet. State the name of a functional
group present in diamorphine (heroin) but
not in morphine.
State the name of the functional group circled on the structure of caffeine.
...........................................................................................................................
(ii)
Deduce which functional group is common to both nicotine and caffeine
State the differences
between the structures of
morphine and diamorphine
(heroin). State the names of
all functional groups in the
molecule of morphine.
• Examples of strong analgesics are morphine,
codeine and diamorphine (heroin).
• Their structures are shown in Table 20 of the
Data Booklet.
• (i) Identify two functional groups present in
all three of these analgesics.
• (ii)Identify one functional group present in
morphine, but not in diamorphine.
Identify the amine functional group in the morphine molecule below by drawing a ring around it.
(ii)
Classify the type of amine present in morphine.
............................................................................................................................. .........
(iii)
State the name of the functional group found in heroin but not in morphine.
......................................................................................................................................
Ampicillin is a semi-synthetic penicillin used to treat lung infections. The structure of the antibiotic is shown below.
Identify two functional groups present in the side chain
(R) of ampicillin by comparing its structure to that of
penicillin in Table 20 in the Data Booklet.
Caffeine is a stimulant with the following structure.
O
CH3
CH3
N
N
O
N
N
CH3
Caffeine
(a)
Determine whether both amine groups in caffeine are primary, secondary or tertiary.
............................................................................................................................. ........
(b)
Caffeine contains the group
O
CH 3
C
N
. State the general name for this functional group.
............................................................................................................................. ........
Tablets of the drug Ecstasy are sometimes contaminated with a substance called 4−MTA.
H
O
CH2
N
CH
H2 C
CH3
O
CH2
CH3
N
CH
H3 C
CH3
S
Ecstasy
(i)
H
4–MTA
Ecstasy and 4-MTA are sympathomimetic drugs. Identify the structural similarity between the two
drugs and epinephrine (adrenaline), the structure of which is given in Table 20 of the Data Booklet.
H
ID ONLY
• CH3-O-CH2-CH3
• CH3—CH2—NH2
methoxyethane (ether)
ethylamine
(amine)
• CH3—CH2—C—NH2 Propanamide (amide)
O
• Objective: SWBAT demonstrate their
knowledge of organic chemistry
Quiz today
Warm up:
What is a homologous series?