Alkanes and Cycloalkanes

hydrocarbons

composed of hydrogen and carbons

IUPAC

the standard of naming for organic and inorganic compounds

International Union of Pure and Applied Chemistry

parent chain

longest continuous chain of carbons

naming parent chain

prefix from C # and suffix ‘-ane’

methane

1 carbon

ethane

2 carbon

propane

3 carbon

butane

4 carbon

pentane

5 carbon

hexane

6 carbon

heptane

7 carbon

octane

8 carbon

nonane

9 carbon

decane

10 carbon

when parent chain is a ring name it

cyclo- then the number of carbons

when are rings the parent chain?

when they have the most carbons

placing locator numbers

we want the substituents to have the lowest #s possible

steps to IUPAC naming

1. identify parent chain

2. # parent chain to give subs. the lowest possible #

3. name sub w/ locator #

4. assemble name: locator # uses hypen, no space between sub and parent

what do you when you have more than one substituent?

identify parent chain

choose #’s that give first sub the lowest #

if its a tie, look at 2nd sub

if the tie cannot be broken default to alphabetical order

naming for more than one sub

1. start as normal (parent chain)

2. order substituents

3. add multiplying prefix

4. add locator #’s for each sub, separated by commas

2 subs

di

3 subs

tri

4 subs

tetra

5 subs

penta

6 subs

hexa

7 subs

hepta

8 subs

octa

9 subs

nona

10 subs

deca

naming for cycloalkanes

distinguish between ring carbons and chain carbons

• ring C >= alkyl C, ring is parent

• Ring C< alkyl C, ring is substituent

methyl

1 carbon in sub

ethyl

2 carbon in sub

propyl

3 carbon in sub

butyl

4 carbon in sub

pentyl

5 carbon in sub

hexyl

6 carbon in sub

heptyl

7 carbons in sub

octyl

8 carbon in sub

isopropyl

3 carbon in sub in a peace sign pattern

alphabetizing complex branching with common names

ignore sec and tert prefixes for alphabetizing

naming complex branching

name complicated chains separately first

number the longest carbon chain within sub. ALWAYS START WITH C ATTACHED TO PARENT CHAIN

name sub and side groups

isomers

same molecular formula, different structure

constitutional isomers

same formula, different connectivity

newman projections

compare relative stability of different confirmations

dihedral angle

angle between atoms on adjacent carbons

anti

methyl groups are farthest apart

gauche

methyl groups experience a gauche reaction (they are closer together)

axial hydrogens

up and down

equatorial hydrogens

side to side

what not to do when drawing chair structures

1. axial is up on a down carbon

2. using wedges and dashes

3. eq. wrong direction

4. something in between axial and eq

rules for drawing chair strucures

ups and downs dont change

we want largest groups in the eq position: more stable

cis

when two groups on the same side of the ring

trans

when two groups are on different sides of the ring

bicyclic compounds

contains two fused rings

bridgehead carbons

carbons where rings are fused together

naming bridgehead carbons

prefix “bicyclo”+[ #] + parent chain

[#]→cont # of c’s in each ring that connect the bridgeheads