Transcript File

Organic Chemistry: Studyspace
of the compounds of Carbon

7 million examples
Inorganic Chemistry: Study of molecules without
Carbon ( 1.5 million examples)
Methane gas
CH4
Hydrocarbons
• Organic molecules consisting only of carbon and
hydrogen with covalent bonds.
• Major components of fossil fuels such as coal, oil or
gas. They consists of partially decomposed remains
of organisms that lived millions of years ago.
• Methane is a fossil fuel, it is easily made in
anaerobic conditions with manure and bacteria (
also in swamps or dumps)
Empirical Formula = formula represents the lowest ratios of the element in
a compound
Molecular Formula = a molecular formula describes the numbers of
different kinds of atoms in a molecule
Structural Formula = a structural formula represents a two-dimensional
model of how the atoms are bonded to each other
Condensed Structural Formula = structural formula written not drawn
Draw a carbon atom
• How many monovalent atoms can bond to
carbon?
• What shape and bond angle will carbon
molecule have?
• What type of bond? Covalent or ionic
Pi Bond
Sigma Bond
• Recall that a molecular
formula (A) describes the
numbers of different kinds
of atoms in a molecule
• a structural formula
represents a twodimensional model of how
the atoms are bonded to
each other. Each dash
represents a bonding pair of
electrons.
• Empirical formula
represents ratios
Carbon skeletons can vary in
length.
Homologous series
• Alkanes occur in what is called a homologous
series.
• A series of compound of uniform chemical type
• Showing gradations in physical properties
• Having a general formula for its members
• Each member having a similar method of
preparation
• Each successive compound differs from the one
before it only by a CH2
Alkanes
•Only have single bonds between carbons (saturated)
•Have maximum amount of Hydrogens
•End with –ane
Ethane
•CnH2n+2
•Fairly unreative but do burn in oxygen, used as fuel due to
high heat of combustion, cheap and clean products
•Tetrahedral shape (not planar) 109.5o angles
•Non-polar so immiscible in water
Alkanes are fairly unreactive (but they
do burn well)
C1-C4 (gas) C5-C12 (liquids)
solids) C32+ (solids).
C13-C31 (waxy
Butane
Defination
• Saturated =
chemical compound that has a chain
of carbon atoms linked together by single bonds and
has atoms filling all of the other bonding orbitals of the
carbon atoms.
(SINGLE BONDS ONLY- FULL)
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Unsaturated compound is a chemical compound that
contains carbon-carbon double bonds or triple bonds, such
as those found in alkenes or alkynes, respectively.
(CONTAINS DOUBLE/ TRIPLE BOND)
C1to C4
Gases
C5 to C16
Liquids
C17 + Waxy Solids
Natural gas is pure methane
Bottles gas is propane and butane
General formula
CnH2n+2
Identify the number of H’s in each alkane
• C5Hx
• C10Hx
• C16Hx
• C55Hx
• C3Hx
• C28Hx
• C21Hx
• C4Hx
• C15Hx
What state?
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Also know how to draw
structural formula
• Must know how to draw from condensed
structural formula
• CH3CH2CH(CH3)CH3
Structural isomers
Are compounds with
same molecular formula
but different structural
formulas
The number of isomers
increases tremendously
as carbon skeletons
increase in size.
Only need to know to C5
2 Structural isomers of butane
Branching
• Skeletons may be branched or unbranched.
Butane
C4H10
2-methylpropane
(commonly called isobutane)
Naming alkanes (IUPAC)
• Identify the longest continuous chain.
• The locations or other groups of atoms attached to
the longest chain are identified and numbered by
counting from the end of the molecule which keeps
the numbering system as low as possible.
• Hydrocarbon groups that are attached to the
longest continuous chain and named using the
parent name and changing the –ane suffix to –yl.
• Groups attached priority is given based on
alphabetical order
Functional groups
• Is an atom or group of atoms which is
responsible for the characteristic properties
of a series of organic compounds
• Eg methyl,ethyl,propyl
• Eg halogens
• Electronegative functional groups increase
the molecules reactivity with polar
molecules and solubility in polar molecule
eg water
Chloroalkanes
• Physical state: Liquid, except for chloromethane and
chloroethane, which are gases at room temperature
• Boiling points higher than the corresponding alkanes, due to
polar C-Cl bond(s) ( but only weak)
• Not soluble in water
• Higher boiling pt than corresponding alkanes (most liquids
except C1 &C2)
• Soluble in non-polar solvents such as cyclohexane
• Because of their weak polarity, they are useful organic solvents,
e.g. for
• removing grease and oil from machinery
• removing oil etc. from clothes - dry cleaning
• Fully halogenated alkanes are flame retardant so used in fire
extinguishers
Naming chloroalkanes
Last part of name comes from base alkane
on which the molecule is built, e.g.
chloroethane [2 carbons]
 Number of chlorine atoms indicated by prefix
mono, di, tri, tetra etc. in front of
chloromethane, e.g. trichloromethane
 Position of each chlorine atom given by a
number before the name, e.g.
1,2,2-trichloropropane
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Alkenes
Alkenes are different to alkanes; they contain DOUBLE
COVALENT bonds.
•CnH2n
•Unsaturated
•Ethene is the 1st member
Ethene
•C2 to C4 are gases, boiling pt increases with increasing carbon
chain
•More reactive than alkane
•Undergoes addition rxns
Bute
ne
•Test for alkenes because they turn bromine water colourless And
acidified KMnO4 colourless.
•planar
Ethene is used to
make polyethene
By polymerisation rxn
(addition rxn with H2
as a by product)
• Ethene is the gas that ripens fruit, and a ripe fruit emits the
gas, which will act on unripe fruit. Thus, a ripe tomato
placed in a sealed bag with green tomatoes will help ripen
them.
• Ethene is used to make ethanol for industrial use
– Naming is similar to naming alkanes except:
• The longest continuous chain must contain the double
bond.
• The base name now ends in –ene.
• The carbons are numbered so as to keep the number
for the double bond as low as possible.
• The base name is given a number which identifies the
location of the double bond. This takes priority to
functional gps
– An alkyne is a hydrocarbon with at least one carbon to
carbon triple bond.
– Naming an alkyne is similar to the alkenes, except the
base name ends in –yne.
– Even more reactive due to triple bond
Aldehydes
-CHO
end in anal
planar
Boiling points higher than the corresponding
alkanes, due to polar +C = O- group, but lower than
the corresponding alcohols
Short chain aldehydes are soluble in
water due to the polar carbonyl group
As the number of carbon atoms in a molecule of the
ester increases, solubility in water decreases, while
solubility in cyclohexane increases
Aromatic aldehyde
Found in almond
kernels
Ketone
• End in -one
• Physical state: Butanone and propanone are liquids at
room temperature
• Boiling points higher than the corresponding alkanes, due
to polar +C = O- group, but lower than the corresponding
alcohols
• Short chain ketones such as propanone are soluble in
water due to the polar carbonyl group
• Ketones are soluble in non-polar solvents such as
cyclohexane
• Propanone is used as a solvent (e.g. In nail varnish
remover)
Carboxylic acid
• End in –oic acid
• Physical state: Methanoic acid and ethanoic acid are liquids, while propanoic
acid and butanoic acid are solids due to H bonding
• Short chain carboxylic acids are soluble in water due to the polar COOH
group
• Carboxylic acids are soluble in non-polar solvents such as cyclohexane
• Boiling points higher than the corresponding alcohols
• This is because carboxylic acids form dimers, where two carboxylic acid
molecules are held together by two hydrogen bonds
• This is possible due to polarity in both the C=O and O-H bonds in each
carboxylic acid molecule
• Methanoic acid is found in the sting of ants and nettles
• Ethanoic acid is the principal acid in vinegar
• Ethanoic acid is used in the manufacture of cellulose acetate
• Propanoic acid, benzoic acid and their salts (e.g. sodium benzoate) are used as
food preservatives
Esters
Esters are formed by the reaction of a carboxylic acid with an
alcohol e.g.
CH3COOH +
Ethanoic acid
CH3OH =
Methanol
CH3COOCH3 + H2O
Methyl ethanoate
The first part of the ester name comes from the parent alcohol with the - anol changed to –
yl and the second part of the name comes from the parent acid with the - oic acid
changed to – oate.
• Physical state: Liquid
• Boiling points higher than the corresponding alkanes, but lower than the corresponding
alcohols
• Soluble in water and non-polar solvents
such as cyclohexane
• As the number of carbon atoms in a molecule of the ester increases, solubility in water
decreases, while solubility in cyclohexane increases
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Occur naturally in fruits – are responsible for their flavours and flowers – are responsible for their pleasant smells
Fats and oils are naturally occurring esters of long chain carboxylic acids
Ethyl ethanoate is used as a solvent for printing inks and paints
Organic
compounds
– An aromatic
compound is a
compound that contain a
benzene ring.
Aliphatic compound is an
organic compound that
consists of open chains of
carbon atoms and closed
chains compounds (ring) that
resemble them in chemical
properties eg cyclohexane and
cyclohexene
Cycloalkanes are alkanes
(only carbon to carbon
single bonds) which form
a ring structure.eg
cyclohexane
• The "straight" chain has
carbon atoms that are able to
rotate freely around their
single bonds, sometimes
linking up in a closed ring.
Ring compounds of the first
four cycloalkanes.
Aromatic Hydrocarbons
• Contain benzene rings
Delocalised
electrons
Benzene: C6H6, unreactive (less than expected), alternating
double and single bonds with bond length between single
and double bond length/ stable/insoluble in water/toxic/
carcinogenic/good organic solvent/planar
Range and scope of aromatic
chemistry
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Methyl benzene is used as a industrial solvent
Pharmaceutical compounds, e.g. Morphine
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Herbicides, e.g. Diuron
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Detergents, e.g. Sodium dodecylbenzenesulfonate
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Dyes, e.g. Martius Yellow
The acid-base indicators phenolphthalein and methyl orange are also aromatic
compounds:Phenolphthalein, Methyl orange
Benzene is carcinogenic
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Homologous series