Download Introduction to Organic Chemistry

Introduction to Organic
Chemistry
Carbon: The key to organic
1. What are the purposes for studying organic chemistry? (Just information, not
test material)
1. Organic chemistry involves a problem solving method that most of you have not
seen before
2. Solving Organic Chemistry problems is a challenge that can be interesting
3. At the beginning of the Chemistry I course, if you are asked where the electrons
are in an atom, you correctly say atomic orbitals. At the beginning of the
Chemistry II course if I ask you how to brominate an alkane, you say use
bromine and light. Did you have to memorize these two facts? No, you became
familiar with these facts by using them and understanding their context. You can
NOT memorize your way through this course.
2. How did it originate?
a. In the earlier period of development of chemistry, chemists tried their best to
synthesize organic compounds in the laboratory. But all their efforts proved to be futile.
Their failures led them to believe that organic compounds could be prepared only by and
within living beings and that they could never be synthesized in the laboratory like
inorganic compounds.
3. What did scientist really believe about organic chemistry and what/who
changed their minds?
a. Jöns Jacob Berzelius, a physician by trade, first coined the term
"organic chemistry" in 1807 for the study of compounds derived from
biological sources. Up through the early 19th century, naturalists and
scientists observed critical differences between compounds that were
derived from living things and those that were not. Chemists of the period
noted that there seemed to be an essential yet inexplicable difference
between the properties of the two different types of compounds. The vital
force theory (sometimes called "vitalism") was therefore proposed (and
widely accepted) as a way to explain these differences. Vitalism proposed
that there was something called a "vital force" which existed within
organic material but did not exist in any inorganic materials.
4. What did Friedrich Wöhler have to do with discrediting the “vital force”
theory?
1. He was widely regarded as a pioneer in organic chemistry as a result of his
synthesizing of the biological compound urea (a component of urine in
many animals) utilizing what is now called "the Wöhler synthesis."
2. in 1828 he heated an aqueous solution of two inorganic compounds,
ammonium chloride and silver cyanate, and produced “urea”.
NH4Cl
Ammonium
chloride
+
AgNCO
Silver cyanate
heat
NH2CONH2 + AgCl
urea
Silver chloride
Urea was a compound that mammals produced to get rid of excess nitrogen. Urea is
secreted in their urine. Friedrich Wohler created it using inorganic (non-living) salts.
Everyone was surprised, but chemists then knew that it was possible to create
chemicals found in the body using chemicals from the ground or air (non-living sources).
So now organic compounds were not defined as only those compounds from
organisms, but compounds based on carbon.
2. Hermann Kolbe, 1845, worked with Wohler, and converted carbon
disulfide (CS2) to acetic acid (CH3COOH)
 a pioneer in the development of structural formulas for
organic compounds.
Introduced the term “synthesis” by discovering many
synthesis methods of organic molecules from inorganic
components.
discovered a method of electrolysis of salts of fatty acids
known as the Kolbe electrolysis.
These experiments opened the floodgates for
synthetically produced compounds.
• This was the final proof to discredit the vitalism theory where
organic compounds have some 'spark' and could only be
created from other organic compounds. The Kolbe synthesis
reaction is a method of making salicylic acid, the main
component of aspirin.
How do the inorganic vs. organic compounds
compare (number wise)?
Five million organic compounds to 2-3 hundred thousand
inorganic compounds.
What is the modern definition of organic chemistry?
Those compounds containing carbon
The exceptions to the rule: carbonates,
cyanides, carbon dioxide, and carbon monoxide.
(These are exceptions because they don’t contain both carbon and
hydrogen)
What is there about carbon that permits the formation of so many
compounds?
1. In addition to binding to hydrogen, carbon can also bind to
other carbon atoms
2. An organic molecule (hydrocarbon)
is formed when carbon bonds to
hydrogen. The simplest hydrocarbon consists
ethane
of 4 hydrogen atoms bonded to a carbon atom
(called methane): Also “CHNOPS” and the
halogens
3. the uniqueness of carbon comes from the fact that it
can bind to itself. Carbon atoms can form long chains:
hexane
4. branched chains:
isooctane
5. rings:
cyclohexane
ORGANIC
VS.
INORGANIC
1. Few elements (CHNOPS)
2. Complex structures (long chains)
3. Insoluble in HOH
1. many elements
2. simple structures
3. most soluble in HOH
4. Low m.p/b.p
4. high m.p/b.p
5. Combustible
5. not combustible
6. doesn’t conduct electric
6. conducts electric current
current
7. Consists of molecules
7. forms ions in solution
8. Slow reaction rates
8. fast reaction rates
9. Side reactions
9. no side reactions
10. High product yield
10. low product yield
10 Carbon Facts—The chemical basis of life
•Carbon is the basis for organic chemistry, as it occurs in all living organisms.
•Carbon is a nonmetal that can bond with itself and many other chemical elements,
forming nearly ten million compounds.
•Elemental carbon can take the form of one of the hardest substances (diamond) or
one of the softest (graphite).
•Carbon is made in the interiors of stars, though it was not produced in the Big
Bang.
•Carbon compounds have limitless uses. In its elemental form, diamond is a
gemstone and used for drilling/cutting; graphite is used in pencils, as a lubricant,
and to protect against rust; while charcoal is used to remove toxins, tastes, and
odors. The isotope Carbon-14 is used in radiocarbon dating.
•Carbon has the highest melting/sublimation point of the elements. The melting
point of diamond is ~3550°C, with the sublimation point of carbon around 3800°C.
•Pure carbon exists free in nature and has been known since prehistoric time.
•The origin of the name 'carbon' comes from the Latin word carbo, for charcoal.
The German and French words for charcoal are similar.
•Pure carbon is considered non-toxic, although inhalation of fine particles, such as
soot, can damage lung tissue.
•Carbon is the fourth most abundant element in the universe (hydrogen, helium, and
oxygen are found in higher amounts, by mass).
Structure of the carbon atom:
Atomic number is 6, mass is 12
Most common isotope: 6 protons, 6
neutrons,
Electron configuration
Valence electrons
Simplest molecule is methane (CH4)
Other names for methane are: swamp gas or marsh gas;
very flammable
Lewis Dot structure of methane
The molecular shape of methane
The bonding capabilities of our organic elements
•Hydrogen and the halogens bond once. (can form single bonds only)
•The family oxygen is in bonds twice. (can form single and double bonds; explain)
•The family nitrogen is in bonds three times. (can form triple bonds)
•The family carbon is in bonds four times. (can bond single, double, and triple bonds)
Structures of organic compounds:
Molecular formula —shows which atoms, and how many
of each, are present in a molecule. C2H6O
Condensed formula – shows the atoms present and the bonds that
connect to each other in a condensed format. ( CH3CH3 )
Expanded structure—shows all atoms and their bonds. examples
Review of the atom:
a. Atomic number
b. orbital
c. Hund’s rule
d. Octet rule, valence electrons
e. Ionic and covalent bonding
f. Lewis structures
g. Nonbonding electrons
h. Draw these: C2H6, C4H10O,CH3Br, C3H8,
C2H7N,C3H8O,C2H5F, C6H14, CH3PO
POLAR AND NONPOLAR MOLECULES
Nonpolar molecules are hydrophobic (means "water
fearing"). They do not dissolve in water.
Nonpolar molecules are hydrophobic
Polar and ionic molecules are hydrophilic.
Nonpolar molecules are hydrophobic. Polar and
ionic molecules are hydrophilic.
Portions of large molecules may be hydrophobic
and other portions of the same molecule may
be hydrophilic.
What is the reason for the many possible
arrangements of the carbon atom?
Isomerism!! The carbon atoms can bond in more than
one arrangement, giving rise to different compounds with
different structures and properties.
Have identical molecular formulas but different
arrangements of atoms
Structural isomers have the same molecular formula but
the atoms bond in different patterns
Example: C2H6O
Functional Groups:
Combination of atoms that differentiates molecules of organic compounds
of one class from those in another.
•functional groups are specific groups of atoms within molecules that are
responsible for the characteristic chemical reactions of those molecules.
The 10 Functional Groups
Term/Definition
•Alkane consists of only carbon to carbon single
bonds
•Alkene consists of at least one carbon to carbon
double bond
•Alkyne consists of at least one carbon to carbon
triple bond
•Alcohol contains an -OH group
•Aldehyde contains a terminal O=C-H group
•Ketone contains an internal C=O group
•Carboxylic acid contains a terminal O=C-OH group
•Ether contains an internal O-O group
•Ester contains an internal O=C-O- group
•Amine contains a terminal NH2 group
Priorities of the groups: Keep rest of
semester.
Subordinate groups: Nitro < halides <
alkoxy
Functional groups: (from least to greatest
in priorities) alkanes < alkynes
<alkenes < amines < phenols < alcohol
<ketones < aldehydes < nitriles < amide
<acid halide < carboxylic esters
<carboxylic anhydrides < carboxylic acids
(TOP DOG).