Download C. Branched Chains and Substitute Groups

Unit I: Biochemistry (CH. 4)
I.
Hydrocarbons
A.
Carbon is the basic element of organic compounds.
-Carbon has 4 valence electrons and likes to share
electrons with other atoms (including itself) to make four
stable covalent bonds.
-Most common partners are hydrogen, oxygen, and
nitrogen.
-Hydrocarbons are a group which have only carbon and
hydrogen. These are what we use as fuel because of the
huge amount of energy stored in these bonds. Living
organisms can not use pure hydrocarbons but many
biological compounds, especially fatty acids, have long
carbon-hydrogen chains with other groups attached.
-Hydrocarbons are non-polar and are not water soluble
(called hydrophobic).
B.
Aliphatic Compounds (chain type or non-aromatic rings)
1.
Alkanes
-Hydrocarbons in which the carbons are joined by a
single non-polar covalent bond.
-Structural formula uses single lines to indicate
bonds between the carbons (also hydrogens).
Ex.
-Alkanes allow for the rotation of bonded atoms
around the singly bonded carbons without causing
isomers. Alkanes can also make structural isomers
(vary in covalent arrangement) and enantiomers
(vary in spatial arrangement). See below.
-To name these compounds use the prefixes
(for the number of carbons) below and add -ane to
the end of the name:
Meth1
Hex6
Eth2
Hept7
Prop3
Oct8
But4
Non9
Pent5
Dec10
2. Alkene and AlkynesAlkenes have double covalent bonds
between the carbons and bonds between
carbons in structural formula is annotated by a
double line.
- Alkynes have triple covalent bonds between
the carbons. Three lines are used to indicate
the triple bond in the structural formula.
- To name these compounds use the correct
prefix and add -ene for an alkene and –yne for
an alkyne and you must give the number
carbon that the double bond/triple bond is
attached to. If there are more than one
double/triple bond you must add a number
prefix such as di, tri, etc. to the ending and
you must give the lowest numbers to those
carbons with the double bonds.
- Ex.
- Considered to be unsaturated and are not able
to rotate like an alkane. Allows for geometric
isomers (vary in arrangement around double
bonds).
C.
Branched Chains and Substitute Groups
1.
Alkyls -Branched
alkanes
with
substitute
hydrocarbon groups. Can be one to several
carbons long but is always one hydrogen
less than usual alkane. It is named by
dropping the –ane with –yl.
Ex. C2H6 (ethane)---- C2H5 (ethyl)
-To name the whole chain you must:
a. Find the longest continuous chain of
carbons for parent name.
b. Number the carbons in the chain (must
number the carbons so the substitute
group is the lowest number possible).
c. Identify the substituents on the chain.
d. Use the appropriate prefixes if there are
more than one of a particular
substituent.
e. Write down the number carbon and the
type of substitute group on that carbon
(follow same rules as above but add –yl
at the end) in alphabetical order if more
than one.
f.
Write down name of carbon chain using
above rules (-ane if single bond, etc.).
Ex.
 Same for alkenes and alkynes but you
must number the double or triple bond so
that it has the lowest number possible
and
place
that
number
before
alkene/alkyne name at the end.
Ex.
2.
Other Substituted Compounds
-Naming of these compounds vary but usually
follow rules that involve using the prefix for the
number of carbons and adding the ending that
pertains to the substituted groups.
-Addition of these functional groups increase the
solubility of the molecules and make them more
hydrophilic (more hydrogen bonding). These
functional groups will give them unique
properties to biological compounds.
a.
Hydroxyl-OH added
-called alcohols when added to a carbon
chain
-ending changes to –ol
Ex.
b.
Carbonyl-have a double bonded oxygen added.
-if oxygen is at the number one of molecule
it is called an aldehyde (ending with –al) if it
is in the middle of the carbon chain it is
called a ketone (ending with -one).
Ex.
c.
Carboxyl-have a double bonded oxygen and a
hydroxyl group (-COOH) at endo of molecule
on number one carbon.
-called carboxylic acids
-ending is –oic or -ic acid.
Ex.
D.
d.
Amino Group-have a –NH2 group attached
-called amines
-forms amino acids (proteins)
Ex.
e.
Sulfhydryl Group-have a –SH group attached
-called thiols
-help stabilize proteins
Ex.
f.
Phosphate Group-have a –PO4 group attached
-essential for energy molecules and DNA
-doesn’t follow any naming pattern
Ex.
Cyclic Hydrocarbons and Aromatic Compounds
1.
Cyclic Hydrocarbons
-When two ends of carbon chain are
attached to form a ring.
-use prefix –cyclo before name of compound
-only number substitute groups if there are
more than one and then by the lowest
number
going
clockwise
or
counter
clockwise.
-complex naming system
Ex.
2.
Aromatic Compounds or Arenes-benzene compounds that are six carbon
rings with resonating double bonds with
varying substituents.
-very stable