chenistry: Functional Groups!! (by Bev)

What are functional groups?

-organic compounds that are comprised elements other than carbon or hydrogen (ex. nitrogen & oxygen)

-tend to be the most reactive part of the molecule

types of functional groups: alcohols, halides, aldehydes, ketones

Halides & Nitro Compounds

-naming: close to that of simple hydrocarbons - can be fixed to alkanes, alkenes, & alkynes (end w/-ANE)

-if there is more than 1 of the SAME halogen/molecule attached to 1 molecule, add the prefix di, tri, tetra, penta, etc. before the halogen/molecule prefix

-if there are DIFFERENT halogens/molecules attached to 1 molecule, list the positions in alphabetical order

(ex. 2,4,4-tribromo-5-chlorononane)

-the main chain name obtains one of these prefixes that are fixed to it

Halogens		Molecules
F	Fluoro	NO2	Nitro
Cl	Chloro
Br	Bromo
I	Iodo

http://hyperphysics.phy-astr.gsu.edu/hbase/organic/imgorg/cform.gif

Ex. 1 (top left):

# of carbon atoms: 1 à methane

# of halogens: 3 Cl in the first carbon position à tricloro

Ex. 2 (top right):

# of carbon atoms: 1 à methane

# of halogens: 4 Cl in the first carbon position à tetrachloro

Ex. 3 (below):

***Note: each empty corner represents ONE carbon atom, thus there are 2 carbons in this molecule! :D

2 carbons = ethane

1 Cl attached in the first carbon position (recall: there isn’t a set direction in which to count the position that the carbon is in; count from the whichever way creates a smaller #, in this case, from left to right)

This compound is called 1-chloroethane or simply chloroethane.

Properties of Halides

-tend to be insoluble in H2O

-compounds combined with fluorine are non-reactive (inert)

Ex. Teflon, which makes up the thin non-stick surface on frying pans

-compounds containing chlorine or bromine are more reactive under extreme conditions

-compounds that have iodine are quite reactive; they can be easily substituted with other functional groups

Properties of Nitro Compounds

-often insoluble in H2O

-inert to chemical attack unless under extreme conditions

-generally explosive

Ex. TNT (trinitrotoluene & nitroglycerine)

-most smell pleasantly fruity

Alcohols

-have an –OH (hydroxyl) functional group

-naming: use the longest carbon chain containing the OH group & replace the ‘e’ ending in the parent hydrocarbon with ‘ol’

-remember: always use the smallest # possible for the OH group even if the branched parts will get a higher # (ex. 4-methyl-2-pentanol rather than 2-methyl-4-pentanol)

-if a molecule contains 2 or more hydroxyl groups, # both and add –diol, -triol, etc. endings