Degree of Akly substitution
primary 1 degree carbon
secondary 2 degree carbon
tertiary 3 degree carbon
Primary (1 degree) Carbon
bonded to only 1 carbon
secondary (2 degree) carbon
bonded to 2 other carbons atoms
tertiary (3 degree) carbon
bonded to 3 other carbon atoms
Foralkanes if themolecules contain “n”carbon atoms then it must contain
(2n+2) hydrogen atoms
prefix for 1 carbon
meth
prefix for 2 carbon
eth
prefix for 3 carbon
prop
prefix for 4 carbon
but
prefix for 5 carbon
pent
prefix for 6 carbon
hex
prefix for 7 carbon
hept
prefix for 8 carbon
oct
prefix for 9 carbon
non
prefix for 10 carbon
dec
prefix for 11 carbon
und
prefix for 12 carbon
dodec
prefix for 13 carbon
tridec
prefix for 14 carbon
tetradec
prefix for 15 carbon
pentadec
prefix for 16 carbon
hexadec
prefix for 17 carbon
heptadec
prefix for 18 carbon
octadec
prefix for 19 carbon
nonadec
prefix for 20 carbon
eicos
Rule 1 for naming alkanes
find the longest continuous chain of carbon atoms and use the name of this compound as the base name
Rule 2 for naming alkanes
the numbering of the carbons begins closest to the substituent that will give that carbon the lowest number
Rule 3 naming akyl groups and location
name the substituent groupos attached to the longest chain as “akyl” groups
- gi e the location of each group by the number of the main chain carbon atom to which H is attached
Example of alkyl groups
CH3= methyl CH3CH2= ethyl CH3CH2CH2= propyl
Rule 4 organizing multiple groups
When 2 or more substituents are present
1 list them in alphabetical order 2.if two or more of the same substituents are present used the prefixes di,=2 tri=3 tertra=4 penta=5 hexa=6 hepta=7
You must include the location of Each
substituents even if it means repeating a number twice
solubilities and densities of alkanes
non polar
hydrophobic
only dissolve in non polar or weakly polar organic solvents
have densities around .7 g/mol
boiling points
increase with smoothly with the increasing # of carbons in simple unbranched alkanes.
branched alkaneshave less surface area exposed therefore
usually have lower boiling points
Melting points of alkanes
simple non branched alkanes increased with the increase number of carbons
There is a slight difference between the melting point of even and odd chain alkanes
- alkanes with even numbers pack into a solid structure better there for have a higher melting point
- alkanes with odd chains do not pack together well and have lower melting points
Alkanes are the ————– reactive class of organic compounds
least
alkanes can undergo a few useful reactions under certain conditions
- energetic
2, heat - heat and catallist
energetic
uses light to aid the reaction
heat
uses increase temperature to aid reaction
heat and catalyst
use heat and adding a catalyst to aid reaction
There are 3 useful reactions of alkanes
- combustion
- cracking and hydrocracking
- halogenation
Combustion
uses heat to promote rapid oxidation that coverts alkanes to CO2 and H2O
Cracking and hydrocracking
uses heat and catalyst to crack large hydrocarbons at a high temperature in order to produce smaller hydrocarbon
hydrocracking involves the use of H2, heat, and catalyst
halogenation
alkanes can react with halogens also using an energetic source such as light.
depending on what halogen is being used, the reaction rates are different
- reactions that include CL2 and Br2 proceed at moderate rates and are easily controlled
- reactions with F2 are to fast and difficult to control
- Iodine-reacts very slowly or nota at all
Conformations
the arrangements formed by rotation about single bond
each individual rotations is called a
conformer
you can draw newman projections of each conformer
you draw it as if you were liking straight down at it
eclipsed newman projection rotates
zero degrees
staggered newman projection rotates
60 degrees
Skew is
zero degrees, anything else
each rotation causes
torsional strain= resistance to twisting
Torsional strains can be studied by looking at the energies of different conformation this is called
conformational analysis
Guache
methyl groups that are directly next to each other on eith the left or the right side in a newman projection
anti conformation
methyl groupos are directly opposite each other
Steric strain
happens when the electron cloud of 2 bulky groups such as a methyl experience a strong reposition to each other due to a close proximity to each other
Conformations of higher alkanes
prefer anti and gauche conformations
lower energy conformation for any straight chain is the
anti conformation, this is what gives the structure of a zigzag shape
Cyclo or cyclic compounds contain rings of atoms
some ex are
carbohydrates that we eat
nucleotides that make up our DNA and RNA
antibiotics
Cycloalkanes are
non polar
melting points and boiling points that depend on molecular weight
since they are held in compact structures their physical properties represent those of branced alkanes
Cycloalkanes can not have
free rotation due to their ridged structure
if the substituents point towards the same face it is
cis
if the substituents pint in the opposite directions then its
trans