Transcript Document

What you should remember from last lecture
1. Organic compounds are based on carbon, and
form the basis of biology and of many of the
materials that you experience every day.
2. Carbon atoms make 4 covalent bonds, to other
carbons and to many other elements in the
periodic table.
3. A tremendous array of structures can be made with
carbon as a building block, and these structures
can display a great range of properties.
What you should remember from last lecture
1. Carbons with 4 single bonds are tetrahedral and organic
molecules are really 3-dimensional blobs, not flat.
Shorthand drawing methods are often used when
drawing organic compounds. Remember, carbon makes
4 bonds, whether all 4 are shown or not.
2. Alkanes are simple CnH2n+2 (saturated) hydrocarbons.
Cycloalkanes are ring structures with molecular
formulae CnH2n.
3. Several isomers (different structures) are possible for
most molecular formulae.
4. For practice, can you draw four different hydrocarbons
with the molecular formula C6H14? How about four
different C5H10 hydrocarbons?
What you should remember from last lecture
1. Alkenes and alkynes are hydrocarbons with C-C
multiple bonds. These compounds are unsaturated.
2. Petroleum (oil) is the source of a wide array of solvents,
fuels, and compounds from which many products can be
made.
3. Petroleum refining begins with distillation, which
separates the hydrocarbons according to their boiling
points.
4. Cracking is a process that breaks larger molecules into
smaller, more valuable ones.
What you should remember from last lecture
• Distillation, cracking, and reforming are essential
steps in the refining of petroleum. Distillation
accomplishes purification, then the next steps
convert the basic component of oil into higher value
products.
• Coal is composed of much larger molecules, and is
much harder to purify and refine. However, there
remain vast reserves of coal while petroleum
reserves will begin to dwindle soon.
• The energy in fuels is stored in chemical bonds.
Chemical reactions that change those bonds can
liberate energy for use.
What you should remember from last lecture
• Functional Groups are commonly occurring groups of
atoms with characteristic reactivity. The chemical
nature of a large, complicated molecule is imply the
nature of the ensemble of functional groups.
• Halogenated compounds (chlorinated or brominated
alkanes, alkenes, and aromatic compounds) have
many highly useful properties and are found in many
everyday products. Some, particularly halogenated
aromatic compounds, are very persistent in the
environment.
What you should remember from last lecture
• Molecular weight, degree of branching, and amount
of crosslinking can affect the properties of the
resulting polymer.
• Polymerization (bond formation between
monomers) can be through addition (polyethylene,
others) or condensation (polyamides, polyesters).
• A plasticizer is often added to a polymer to make it
soft and plastic.
• Rotation around C=C bonds is difficult. This leads
to a new type of isomerism: stereoisomerism
Cl
H
CH3
Cl
cis
CH3
H
trans
What you should remember from the last lecture
• Carbon is not the only element that can form the
backbone of a polymer. Silicone has silicon and
oxygen as a backbone.
• Crosslinked polymers (like epoxy) tend to be hard,
inflexible, and durable.
• Composite materials are formed when a reinforcing
material (glass fiber, graphite fiber) is blended into a
matrix material (usually a polymer). Composite
materials are usually stiffer and stronger than the
pure polymer matrix.
What you should remember from last lecture
• Oxygen is a common component of organic
compounds, appearing in many functional groups,
including alcohols, carboxylic acids, and esters.
These functional groups appear in many molecules
that are important components in personal care
products.
• Oxygen-containing functional groups tend to make
molecules more polar. Hydrocarbons are non-polar.
Water will interact strongly with other polar
molecules, but not with non-polar (greasy) ones.
What you should remember from the last lecture
• Fats (triglycerides) can be completely (or partially)
converted (saponified) into fatty acids and glycerol, or
fatty acids and mono- (or di-) glycerides.
• Fatty acids are the basis of soaps. These are effective
cleaning agents, as they form micelles with non-polar
interiors. Fatty acid salts with calcium are insoluble,
and form soap scum.
• Alkyl benzene sulfonates, alkyl sulfates and non-ionic
surfactants like polyethylene glycol (PEG) are cleaning
agents that remain soluble when bound to calcium.
What you should remember from the last lecture
Some organic molecules are Chiral. Chiral
objects are not identical to their mirror images.
Molecules that contain a carbon that is bound to
4 different things are usually chiral.
Many important biomolecules (molecules of life)
are chiral, including most carbohydrates and
amino acids, the building blocks of proteins.
Carbohydrates (saccharides) are sugars. Simple
sugars have the molecular formula Cn(H2O)n.
These compounds usually exist as 5- or 6membered rings containing one oxygen atom.
What you should remember from last lecture
1. Simple sugars have the Cn(H2O)n formula.
Disaccharides are fomed by condensation of two simple
sugar molecules.
2. Polysaccharides are polymers of sugars, and the
specific polysaccharide depends on the monosaccharide
monomers and how they are linked (position and
geometry).
3. Steroids have a characteristic structure consisting of 4
fused rings. Steroids can have potent biological activity
as hormones, anti-inflammatory agents, and others.