Transcript Ch. 10: Organic Chemistry

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The chemistry of carbon compounds.
Mainly carbon and hydrogen atoms.
Many organic compounds occur naturally.
Thousands more can be synthesized by man.
Inorganic
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NaCl, 58.5 g/mol
Bonding is ionic
M.P. = 801oC
B.P. = 1413oC
Dissolves in water
Will not burn
Organic
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C4H10, 58.1 g/mol
Bonding is covalent
M.P. = -138oC
B.P. = 0oC
Not soluble in water
Will burn in air
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5.
Decide whether the property is that of
pentane (C5H12) or sodium sulfide (Na2S).
Liquid at room temperature.
Dissolves in water.
Floats on the surface of water.
Has a melting point of 1176oC.
Burns in air easily.
The bonding in all organic molecules is
covalent.
•Carbon has 4 valence electrons and
hydrogen has 1.
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•C•
H•
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•Carbon achieves an octet by forming four
bonds.
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When carbon is bonded to four other atoms,
it has a tetrahedral geometry.
Aliphatic
Saturated
Alkanes
Aromatic
Unsaturated
Cycloalkanes
Benzene Ring
Alkenes
Alkynes
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Molecular formula – shows the number of C and H
atoms.
Ex) Propane, C3H8.
Complete structural drawing – shows every single
bond.
H H H
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H–C–C–C–H
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H H
H
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Condensed structural formula – writes each C
atom along with the number of H’s bonded to
that carbon atom.
CH3 – CH2 – CH3
This is the preferred method for showing
structures in this course.
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A set of rules for naming all organic
compounds.
Will not need to memorize the base names.
Names for one through ten carbons.
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Butane, C4H10, has more than one possible
way to put four carbons together.
These two forms are called structural
isomers.
Both can NOT be called butane!
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A substituent is any group that is attached to
the longest chain of carbon atoms.
CH4 = methane, -CH3 = methyl
CH3CH3 = ethane, -CH2CH3 = ethyl
Cl = chloro, Br = bromo, I = iodo
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Determine the longest continuous chain of
carbon atoms. Because the alkanes have
free rotation, the chain may bend and twist
in many shapes!
Determine the type of substituents located
on the longest chain. These are named in
alphabetical order.
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Number the longest chain such that the
substituents have the lowest numbers.
Name the substituents first followed by
the base name. If two or more of the
same substituent, then use prefixes.
Every substituent MUST have a number in
front of it indicating the position on the
chain.
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A ring structure can be constructed from
alkanes of three or more carbons by
removing two hydrogen atoms.
Because they form a geometric shape, a
shorthand method for their structure is that
shape.
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For ring structures, a mono-substituted ring
does not need a number.
Why???
For di-substituted ring structures, number
starting from the location of one the
substituents and then go CW or CCW to give
the next one the lowest number.
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A haloalkane is placing a halogen (group 7A)
atom in place of a hydrogen atom.
Naming uses the fluoro, chloro, bromo, and
iodo names.
Haloalkanes are used as refrigerants
(CF3CH2F) and anesthetic agents (CF3CHClBr).
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When converting a name to a condensed
formula, you may want to do it in several
steps.
Base name = carbon backbone.
Fill in substituent groups.
Add H’s until each carbon has four bonds.
Condense.
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Alkanes are non-polar and, thus, do NOT
dissolve in water.
Alkanes typically have a density of 0.65 –
0.70 g/mL and will float on the surface of
water.
All alkanes can be burned to produce energy.
Alkane + O2  CO2 + H2O
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Crude oil contains a variety of alkanes that
are separated at an oil refinery.
The mixture is heated and then separated by
fractions – that is, their differences in boiling
points.
The lightest alkanes have the lowest boiling
points and go to the top of the column.
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Alkanes are fairly unreactive and have little
use to organic chemists.
Addition of other atoms like O, N, and S
change the reactivity and properties of the
boring alkanes and these are called functional
groups.
Functional groups are classified into several
common identifiers.
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Use of the letter “R” in generic formulas.
Alcohol – contain the hydroxyl (O-H) group.
R-OH
Ex) CH3CH2OH, CH3CHCH3
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OH
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Ether – an oxygen atom separating two alkyl
groups.
R – O – R’
Ex) CH3CH2-O-CH2CH3
Carbonyl group, C=O, is found in a couple of
different ways.
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Aldehyde – the carbonyl group is on the end
of the chain.
RCHO
Ex) CH3CH2C=O
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H
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Ketone – the carbonyl group is in the middle
of the chain.
R(C=O)R’
Ex) CH3 – C – CH3
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O
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Carboxylic acid – has both the carbonyl and
the hydroxyl groups.
RCOOH
Ex) CH3 – C – OH
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O
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Ester – combines the carbonyl group and the
ether group.
R-COO-R’
Ex) CH3CH2CH2 – C – O – CH3
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O
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Amine – is a nitrogen atom that can be
bonded to one, two, or three alkyl groups.
RNH2 , R2NH, and R3N (note: R groups can be
different!).
Ex) CH3 – NH2 , (CH3)3N
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Thiol – is a sulfur atom with one H atom
(usually).
R-SH
CH3CH2 – SH
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Alkenes, alkynes, and aromatics can also be
considered as a functional group.
All of these will be discussed in greater
details in the following chapters including
naming, properties, and important reactions.