Download Metathesis Problems (and Some Solutions) Identified Through

Chapter 19: Organic chemistry
Chemistry 1020: Interpretive chemistry
Andy Aspaas, Instructor
Organic compounds
• Organic compounds: carbon containing compounds
– Specifically, with carbon-carbon covalent bonds
– Carbonates, CO2, CO are not organic
• VSEPR theory: carbon has 4 electron pairs
– A tetrahedral electron pair arrangement
– 4 covalent bonds, no lone pairs
– Tetrahedral molecular shape as well
Hydrocarbons and alkanes
• Hydrocarbons contain only carbon and hydrogen
• Alkanes are hydrocarbons with only single bonds
(no double or triple bonds)
– Saturated: only single bonds
• Simplest alkane: methane, CH4
• Ethane, molecular formula C2H6
– Structural formula (indicates connectivity) is
CH3CH3
Straight-chain alkanes (1 C through 4 C)
• Straight-chain (or “normal”) alkanes have carbons
all attached in a row
• n- at beginning indicates straight-chain (normal)
Name
Methane
Molecular formula
CH4
Structural formula
CH4
Ethane
C2H6
CH3CH3
Propane
C3H8
CH3CH2CH3
n-Butane
C4H10
CH3(CH2)2CH3
Straight-chain alkanes (5 C through 10 C)
• For straight-chain alkanes 5 C through 10 C, use
Greek prefix followed by -ane
Name
Molecular formula
Structural formula
n-pentane
C5H12
CH3(CH2)3CH3
n-hexane
C6H14
CH3(CH2)4CH3
n-heptane
C7H16
CH3(CH2)5CH3
n-octane
C8H18
CH3(CH2)6CH3
n-nonane
C9H20
CH3(CH2)7CH3
n-decane
C10H22
CH3(CH2)8CH3
Isomerism in alkanes
• n-Butane has an isomer (same number and kind
atoms, different bonds)
– Same molecular formula, different structural
formula
• Isobutane: branched, all carbons not in a row
CH3
• CH3(CH3)CHCH3
H3C C CH3
H
Isomerism in alkanes
• Iso- prefix means branched once
• Neo- prefix means branched twice
– n-Pentane, isopentane, neopentane
• More complex branched alkanes require different naming
rules
– Any of the straight-chain alkanes can be made into
“substitutents” - or branches off a main chain
– Methane becomes methyl as a branch (—CH3)
– Ethane becomes ethyl as a branch (—CH2CH3), etc
Naming complex branched alkanes
• Start by identifying the longest carbon chain
• Identify branches off the longest chain as their
substituent name (methyl, ethyl, propyl, etc)
• Number longest chain starting at end closest to the
first branch
• Name the compound, starting with branches and
indicating the number on the main chain to which
the branch is attached
Naming branched alkanes
H3C
CH2
CH2
H3C CH
H2C
H
C
CH2
H3C CH
CH3
CH2CH3
• First identify longest chain (9
carbons)
• Number chain starting at end
closest to a branch
• Identify branches by first
numbering them (from main
chain number)
– 2-methyl, 4-ethyl,
6-methyl
• Combine identical branches
by saying 2,6-dimethyl
• Then give chain name
• 4-ethyl, 2,6-dimethyl nonane
Alkenes and alkynes
• Alkenes: hydrocarbons with carbon-carbon double
bonds
• Alkynes: hydrocarbons with carbon-carbon triple
bonds
• Name by first finding longest carbon chain
• Chain name is same as alkane, but end is -ene for
double bond, -yne for triple bond
• Start numbering on end closest to double/triple bond
• Location of multiple bond is given by the smaller
numbered carbon involved in the bond
Functional groups
• Most organic molecules are simply hydrocarbons
with different groups of atoms attached
– Functional groups: common groups of atoms
found in organic molecules
Common functional groups
O
• Alkyl halide: –X (where X is
F, Cl, Br, or I)
• Alcohol: –OH
• Ether: –O–
O
• Aldehyde:
C H
O
• Ketone:
C
• Carboxylic acid:
O
• Ester:
C O
O
• Amine: –NH2C
OH
C OH
Alcohols
• Alcohols: R–OH
• Methanol: CH3OH
– Starting material in synthesis of chemical
products
– Racecar fuel
– Highly toxic, causes blindness
• Ethanol: CH3CH2OH
– Formed by fermentation of glucose
– Important gasoline additive
Carboxylic acids
O
R C OH
• Carboxylic acid: R–COOH
• Name by dropping –e from parent hydrocarbon name, and
adding –oic acid
– CH3COOH: ethanoic acid (acetic acid is common
name)
– CH3CH2CH2CH2COOH: pentanoic acid
Esters
O
•
•
•
•
Esters: RCOOR’
R C O R'
Formed by reaction of carboxylic acid and alcohol
RCOOH + R’OH  RCOOR’ + H2O
Name by first using alcohol fragment as a fragment name
– Then add root of carboxylic acid followed by –ate
• Ex. Acetic acid + ethyl alcohol  ethyl acetate