Download Chapter 22 Organic chemistry

Chapter 22
Organic chemistry
 chemical compounds consisting primarily
of carbon
 original definition came from the
misperception that these compounds
were always related to life processes
Structure of carbon




1s2 2s2 2p2
4 valence electrons (2s2 2p2)
Strong tendency to share electrons
Strong tendency to form covalent bonds
Molecular Architecture
 4 covalent bonds
 tetrahedron
 Strong tendency to form covalent bonds
w/ H, O, N, S, P, and halogens
Molecular Diversity
 Also bond to other carbons to form
chains, rings, plates, networks
Forms of carbon
1. Diamond



Hardest known material
High density (3.514 g/ cm3)
High mp (3550 deg. C)
2. Graphite




Soft
Conducts electricity
High mp (3570 deg. C)
Used as a lubricant, “lead” pencils
3. Coal


Black, rock-like
Burns readily
4. Coke


Made by heating coal
Used for making steel
5. Charcoal
Carbon Compounds
 Over 4 million known cmpds., natural and
synthetic
 Almost limitless # of possible structures
Can form isomers
 Compounds w/ same formula but
different structures
Hydrocarbons
 Compounds of hydrogen and carbon
1. Alkanes
 Hydrocarbons in which all carbon atoms
are connected by single bonds
 Saturated –
Each carbon atom is connected by single
bonds
e.g. 2-methylheptane
 Naming of alkanes
(p. 582)
meth, eth, prop, ……….
+ ane
e.g. methane
 Alkyl groups
Sources and uses of
alkanes
 Most from petroleum & natural gas
 e.g. natural gas is 90 % methane
 gasoline: heptane, isooctane, ….
Substitution reaction
Alkenes
 Double bond between carbons
 e.g. ethene
 Naming: use alkane name, drop –ane,
add –ene
 Unsaturated (one or more double bond)
 Addition reaction:
Alkadienes
 2 double bonds
 e.g. 1,3 butadiene
Polymers
 Lg. molecule made of repeating subunits
 e.g. polyethylene
Alkynes
 Triple bond
 e.g. ethyne
 Common name: acetylene
Cycloalkanes
 e.g. cyclopentane
Aromatic hydrocarbons
 e.g. benzene
Exhibit resonance:
para-dichlorobenzene
Examples of hydrocarbons
1. Petroleum

fractional distillation
2. Rubber

vulcanization
Alcohols
 Hydrocarbons with one or more hydroxyl
(-OH) groups
 e.g. 1-propanol
 Drop the –e of propane and add -ol
Preparation of alcohols
Common alcohols
 Methanol (wood alcohol)
 Ethanol (grain alcohol)
often denatured =
 Ethylene glycol
Halocarbons
 Alkanes in which one or more halogens
are substituted
e.g.
e.g.
dichloromethane
tetrachloromethane
(carbon tetrachloride)
 Dichloro-diphenyl-trichloroethane
(DDT)
 Polytetrafluoroethylene (PTFE) or
Teflon
Ethers
 Two hydrocarbon groups are bonded to
the same oxygen atom
Dimethyl ether
methyl ethyl ether
Aldehydes and Ketones
 Substituted hydrocarbons with a carbonyl
group
Aldehydes
 The carbon of the carbonyl group is
attached to at least one H
Aldehyde naming
 Drop the –e from the alkane name anf
add –al
methanal
ethanal
 (common name formaldehyde)
Ketones
 Both bonds of the carbonyl group
attached to carbons
Ketone naming
 Drop the –e of the alkane name and add
–one
propanone
(common name acetone)
cinnamaldehyde
vanillin
piperine
Carboxylic Acids
 Contain the carboxyl group
Carboxylic acid naming
 Drop the –e and add –oic acid
ethanoic acid
(common name: acetic acid)
Esters
 General formula
Ester naming
 Name of the R’ group first + name of acid
represented before substitution of H with
R’ group
Drop –ic of acid name and add -ate
Preparation of esters
saponification
Common esters
Interesting organic
compounds
1.polystyrene
2. trinitrotoluene