“Organic compounds and Nomenclature”

Root of the name

This depends on the number of carbon atoms in the longest unbroken chain.

1 carbon chain …. Meth-

2 carbon chain …. Eth-

3 carbon chain …. Prop-

4 carbon chain …. But-

5 carbon chain …. Pent-

The “default”

This is a hydrocarbon that contains only single bonds. It has the suffix (ending) –ane

Example

A three carbon chain with only carbons, hydrogens and single bonds is called propane. CH3CH2CH3

Unsaturation

If a molecule contains double or triple bonds it is said to be unsaturated (meaning that it would be possible to fit in more hydrogens if the double bonds were changed to single).

Chains with one double bond take the suffix -ene. Example: ethene CH2=CH2

Chains with one triple bond take the suffix –yne. Example: Ethyne CHΞCH

Functional Groups

Most organic chemistry involves substituents–often contain the elements O, N,

S, or P–also called “functional groups”-

they are the chemically functional part of the molecule, and are the non-hydrocarbon part

Functional GroupsFunctional group - a specific

arrangement of atoms in an organic compound, that is capable of characteristic chemical reactions.–What is the best way to classify

organic compounds? By their functional groups.

Functional GroupsThe symbol “R” is used to

represent any carbon chains or rings

These are called alkyl groups CH3 - methyl group CH3CH2 - ethyl group CH3CH2CH2 - propyl group

Halogen Substituents Halogenocarbons - class of

organic compounds containing covalently bonded fluorine, chlorine, bromine, or iodine–General formula: R-X

Naming? Name parent as normal, add the halogen as a substituent (or prefix) -

Halogen Substituents

The more highly halogenated the compound is (I.e. the more greater the number of halogen atoms), the higher the b.p.

Few halogenoalkanes are found in nature….– but, readily prepared and used– halothane and also the

hydrofluorocarbons

Alcohols and Ethers

OBJECTIVES:

–Describe the structures and naming of alcohols and ethers.

Alcohols Alcohols - a class of organic

compounds with an -OH group

– The -OH functional group in alcohols is called a “hydroxyl” group; thus R-OH can represent the formula, where “R” is an alkyl group

How is this different from the hydroxide ion? (covalently bonded to the carbon- not ionically as in hydroxides)

Alcohols Both systematic and common names systematic:

–drop the -ane ending of the parent alkane name; add ending of -anol, number the position of –OH if needed

–parent is the longest chain that contains the carbon with the attached hydroxyl.

AlcoholsThe hydroxyl group is given

the lowest position numberAlcohols containing 2, 3, and 4

of the -OH substituents are named diols, triols, and tetrols respectively (not needed fro year 10)

AlcoholsCommon names:

–similar to halogenoalkanes, meaning name the alkyl group root followed by the suffix -anol

–One carbon alcohol = meth- anol = methanol

Properties of Alcohols

Glycerol (propan 1,2,3 triol) - used as a moistening agent in cosmetics, foods, and drugs; also a component of fats and oils

Ethyl alcohol (ethanol) used in the intoxicating beverages; an important industrial solvent

Ethers A class of organic compounds in which

oxygen is bonded to 2 carbon chains: R-O-R is the formula

Nomenclature: The larger of the two R groups is the root and the other R group is prefixed as alkoxy-

Example:

CH3CH2OCH3 methoxyethane

Alkanals and Alkanones The C=O group is called the

“carbonyl group”

–it is the functional group in both alkanals and alkanones

Alkanals - carbonyl group always joined to at least one hydrogen (meaning it is always at the end!)

Alkanones

Alkanones - the carbon of the carbonyl group is joined to two other carbons (meaning it is never on the end)

Alkanals and alkanones Nomenclature

–Alkanals: identify longest chain containing the carbonyl group, then the -ane ending replaced by -anal, such as methanal, ethanal, etc.

–Alkanones: longest chain with the carbonyl, then new ending of -anone; number it

propanone, 2-pentanone, 3-pentanone

Aldehydes and Ketones

Propanone (common: acetone) is a good solvent; miscible with water in all proportions

why is it a good substance used in nail-polish removers? (a powerful solvent-able to dissolve both polar & non-polar substances)

Carboxylic Acids Also have a carbonyl group (C=O),

but is also attached to a hydroxyl group (-OH) = “carboxyl” group

general formula: R-COOH–weak acids (only slightly

dissociate into ions) Named by replacing -ane with -

anoic and followed by the word acid methanoic acid; ethanoic acid

Carboxylic Acids Abundant and widely distributed in

nature, many having a Greek or Latin word describing their origin

–acetic acid (ethanoic acid) from acetum, meaning vinegar

–many that were isolated from fats are called fatty acids