unit 3organic chemistry
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Unit 3Organic Chemistry. Chemistry 2202. Introduction. Organic Chemistry is the study of the molecular compounds of carbon. eg. CH 4 CH 3 OHCH 3 NH 2 Organic compounds exclude oxides of carbon and ions containing carbon. ie. CO, CO 2 , KCN, CaCO 3 - PowerPoint PPT PresentationTRANSCRIPT
Unit 3 Organic Chemistry
Chemistry 2202
Introduction
Organic Chemistry is the study of the molecular compounds of carbon.eg. CH4 CH3OH CH3NH2
Organic compounds exclude oxides of carbon and ions containing carbon.ie. CO, CO2, KCN, CaCO3
are NOT organic compounds!!
History of Organic Chemistry
Organic chemistry can be traced back to ancient times when medicine men extracted chemicals from plants and animals to treat members of their tribes
Organic chemistry was first defined as a branch of modern science in the early 1800's by Jon Jacob Berzelius
Berzelius believed in Vitalism - organic compounds could only originate from living organisms through the action of some vital force
organic compounds originate in living or once-living matter
inorganic compounds come from "mineral" or non-living matter
In 1828, Friedrich Wöhler discovered that urea - an organic compound - could be made by heating ammonium cyanate (an inorganic compound).
NH4OCN(aq) (NH2)2CO(s)
inorganic organic
organic chemistry branched into disciplines such as polymer chemistry, pharmacology, bioengineering and petro-chemistry
98% of all known compounds are organic
The huge number of organic compounds is due mainly to the ability of carbon atoms to form stable chains, branched chains, rings, branched rings, multiple rings, and multiple bonds (double and triple bonds) to itself and to many other non-metal atoms.
Sources of Organic Compounds
1. Carbonized Organic Matter- fossil fuels such as coal, oil, and
natural gas - basis for the petrochemical industry
2. Living Organisms eg: - penicillin from mold
- ASA from the bark of a willow tree
3. Invention
- antibiotics, aspirin, vanilla flavoring, and heart drugs are manufactured from organic starting materials
- plastics
Structural Isomers
Structures that have the same molecular formula but different structural formulas are called structural isomers
eg. C4H10
Practice: Draw all structural isomers of C5H12 and C6H14
Structural Isomers
structural isomers have the same chemical formula but have different chemical and physical properties.
Classifying Organic Compounds
Organic Compounds
HydrocarbonsHydrocarbonDerivatives
hydrocarbons consist of carbon and hydrogen atoms only
eg. Methane - CH4 hydrocarbon derivatives have one
or more hydrogen atoms replaced by another nonmetallic atom
eg. bromomethane - CH3Br
methanol - CH3OH
Hydrocarbons
AliphaticHydrocarbons
Aromatic Hydrocarbons(benzene based)
AlkAnes
AlkEnes
AlkYnes
aliphatic hydrocarbons have carbon atoms bonded in chains or rings with only single, double, or triple bonds
aromatic hydrocarbons contain at least one 6 carbon benzene ring
Aliphatic Hydrocarbons
1. AlkanesAlkanes are hydrocarbons that have
only single bonds between carbon atoms
general formula CnH2n+2
eg. C3H8 C6H14
IUPAC prefixes
Prefix # of carbon atoms
meth 1
eth 2
prop 3
but 4
pent 5
hex 6
hept 7
oct 8
non 9
dec 10
Complete this table for the first 10 alkanes
methane CH4
ethane
propane
A series of compounds which differ by the same structural unit is called a homologous series
eg. each successive member of the alkanes increases by CH2
Representing Alkanes (4 ways)
1. Structural formulas
eg. propane
H – C – C – C – H
HHH
HHH
Hydrogen atoms may be omitted from structural formulas
eg. propane
– C – C – C –
2. Condensed Structural Formula
eg. propaneCH3-CH2-CH3
3. Line Structural Diagrams
eg: propane
(the endpoint of each segment is a carbon atom)
4. Expanded Molecular Formulas
eg. propane
CH3CH2CH3
Alkyl Groups
An alkyl group has one less hydrogen than an alkane.
General Formula: CnH2n + 1
To name an alkyl group, use the prefix to indicate the # of carbon atoms followed by the suffix –yl
eg. -C7H15 heptyl
Alkyl Groups
methyl -CH3
ethyl -C2H5 or -CH2CH3
propyl -C3H7 or -CH2CH2CH3
Alkyl Groups
Branched alkanes are alkanes that contain one or more alkyl groups
eg.
Naming Branched Alkanes
1. Find the longest continuous chain of carbons and name it using the alkane name. This is the parent chain.
2. Number the carbons in the parent chain starting from the end closest to branching. These numbers will indicate the location of alkyl groups.
Naming Branched Alkanes
3. List the alkyl groups in alphabetical order. Use Latin prefixes if an alkyl group occurs more than once. (di = 2, tri = 3, tetra = 4, etc.)
4. Use a number to show the location of each alkyl group on the parent.
Naming Branched Alkanes
5. Use commas to separate numbers, and hyphens to separate numbers and letters.
Naming Branched Alkanes
eg.
7 6 5 4 3 2 1
ethyl
methyl
4-ethyl-3-methylheptane
Naming Branched Alkanes
Practice:p. 336 - 339 #’s 5 - 11
Alkenes and Alkynes
saturated compounds contain only single bonds between carbon atoms
eg. alkanessaturated compounds have the
maximum number of hydrogen atoms bonded to carbon atoms
Alkenes and Alkynes
unsaturated compounds contain double or triple bonds between carbon atoms
eg. alkenes and alkynes
Alkenes and Alkynes
General Formulas:
AlkenesCnH2n
AlkynesCnH2n - 2
Naming Alkenes and Alkynes
1. Name the longest continuous chain that contains the double/triple bond. Use the smallest possible number to indicate the position of the double or triple bond.
Naming Alkenes and Alkynes
2. Branches are named using the same rules for alkanes. Number the branches starting at the same end used to number the multiple bond.
Naming Alkenes and Alkynes
p. 347 #’s 17 - 19p. 354 #’s 28 & 29
Cyclic Hydrocarbons
Pp. 356 – 358questions 30 & 31
cyclopentane
methylethyl
1-ethyl-3-methylcyclopentane
3-ethyl-1-methylcyclopentane
1
2
3
methyl
1,2,3,4-tetramethylcyclohexane
Aromatic Compounds
Aromatic hydrocarbons contain at least one benzene ring.
The chemical formula for benzene, C6H6 , was determined by Michael Faraday in 1825.
Structural formula was determined by August Kekulé in 1865.
Aromatic Compounds
benzene ring consists of six carbon atoms, each of which is bonded to a hydrogen atom (Try to draw this!!)
C6H6 can be drawn with alternating single and double bonds.
Aromatic Compounds
While C=C double bonds are shorter than C-C single carbon bonds, x-ray crystallography shows that all six C-C bonds in benzene are the same length.
Benzene molecules behave like alkanes in chemical reactions, not like the alkenes
Aromatic Compounds
Kekulé thought benzene could exist in two forms and used the idea of resonance to explain its structure.
The resonance structure is an average of the electron distributions.
Aromatic Compounds
or
Aromatic Compounds
bonding electrons that were thought to be in the double bonds are delocalized and shared equally over the 6 carbon atoms
the bonds in benzene are like “1 ½” bonds – somewhere between single and double.
Naming Aromatic Compoundsan alkyl benzene has one or more H
atoms replaced by an alkyl group.name the alkyl groups, using
numbers where necessary, followed by the word benzene.
Aromatic Compounds
methylbenzene
propylbenzene
ethylbenzene
Aromatic Compounds
1,3-dimethylbenzene
1,4-dimethylbenzene
1,2-dimethylbenzene
Aromatic Compounds
ortho- means positions 1 and 2 and is represented by an italicized "o"
meta- means positions 1 and 3 and is represented by an italicized "m"
para- means positions 1 and 4 and is represented by an italicized "p"
Aromatic Compounds
m-dimethylbenzene
p-dimethylbenzene
o-dimethylbenzene
Aromatic Compounds
Benzene is treated as a branch if it is not attached to the terminal carbon of an alkyl group
Benzene as a branch is called phenyl
Aromatic Compounds
CH2
CH2
CH3
CH3CHCH3
propylbenzene2-phenylpropane
Aromatic Compounds
CH3CHCHCH2CH2CH3
CH2
CH3
Aromatic Compounds
CH3CHCHCH2CHCH2CH2CH3
CH2
CH2
CH3
CH3
Aromatic Compounds
p. 361 #’s 32 – 35
Hydrocarbons Practice
pp. 363, 364
#’s 4 – 9Test!!
Hydrocarbon Derivatives
Hydrocarbon Derivatives have one or more H atoms replaced by another nonmetallic atom
Types of derivatives:carboxylic acidsorganic halidesesters
alcoholsethersaldehydesketones
Hydrocarbon Derivatives
A functional group is the reactive group of atoms that gives a family of derivatives its distinct properties.
The general formula for a derivative is
R - functional group
where R stands for any alkyl group.
Bonded to
Hydrocarbon Derivatives
eg. ALCOHOLS R-OH
ethanol C2H5OH
propanol C3H7OH
CARBOXYLIC ACIDS R-COOH
ethanoic acid CH3COOH
propanoic acid C2H5COOH
hydroxyl group
carboxyl group
Hydrocarbon Derivatives
Types of derivatives (See p. 378)Alcohols – pp. 386 - 388Ethers – pp. 394 – 396Aldehydes & Ketones – pp. 402,403Carboxylic Acids – pp.405, 406Alkyl Halides – pp. 390, 391Esters – pp. 410, 411