Activity 1: Nomenclature of Hydrocarbons and Low-Priority Substituents

Organic Chemistry

is the branch of chemistry that deals with the chemistry of living “organic” substances. (ex. substances from animals and plants)

True or False: Some organic substances contains a CARBON atom in their structure

False: ALL organic substances contains a CARBON atom in their structure.

Hydrocarbons

composed entirely of C and H atoms

Hydrocarbon derivatives

composed of C, H, and one or more element. other elements commonly found in molecules are N, O, S and X (halogens).

True or False: Carbon atoms will always require 4 bonds to meet its octet.

True: There are possible ways to make the 4 bonds:

• Four single bonds

• Two single bonds and one double bond

• Two double bonds

• One triple bond and one single bond

True or False: Hydrocarbons are organic compounds composed entirely of carbon and hydrogen atoms.

True: They can be classified into:

• Alkanes

• Alkenes

• Alkynes

• Aromatic

Alkanes

saturated HC composed purely of single bonds connecting the carbon atoms in the structure.

Alkenes

unsaturated HC composed mainly of single bonds connecting the carbon atoms with at least one C-C double bond in the structure.

Alkynes

unsaturated HC composed mainly of single bonds connecting the carbon atoms with at least one C-C triple bond in the structure.

Aromatic

cyclic, unsaturated compounds with a conjugated set of double bonds and passed the Huckel’s rule. The simplest of these is benzene.

Different Structural Formulas:

• Kekule or Expanded Formula

• Condensed Formula

• Skeletal Formula

Kekule / Expanded Formula

shows all bonds between all atoms represented by atomic symbols.

Condensed Formula

single bonds connecting atom (atomic symbols) are hidden but double and triple bonds are shown. Sometimes even the double bond for carbonyl group (C=O) is also hidden.

Skeletal Formula

all carbon atoms are represented as points connected by drawing respective single, double, or triple bonds. Bonds connecting atoms within a functional group (ex. OH, NH, SH, COOH) and bonds connecting a carbon and hydrogen are not drawn anymore.

Nomenclature

Nomenclature of organic compounds is important as it provides basic information about the compound like the properties that can be expected and its possible reactivity.

Types of Nomenclature:

1. Trivial names

2. Semi-systematic names

3. Systematic (IUPAC) names

Trivial Names

the “nick name” of the compound based solely on tradition and familiarization by people. It does not depict the precise structure of the compound in question.

Example. Phenol, Acetic Acid, Toluene

Semi-systematic names

the name of the compound that describe only partially the structure of the compound in question due to a set of rules not being utilized in the nomenclature process.

Example. Methane, Propanol, Benzoic Acid

Systematic (IUPAC) names

the “real name” of the compound based on specialized naming rules. It aims to describe the number, location and precise structure of the compound in question.

Example. Propan-1-ol, Benzenecarboxylic acid, Ethanoic acid

Rules for HC Nomenclature

• Low-priority substituents are always used as a prefix in systematic nomenclature. Principal groups are always used as a suffix (except in the presence of two or more principal groups in a structure).

• Principal groups are arranged from highest to lowest priority (carboxylic acid with the highest priority). All low priority substituents are equally ranked.

• The low priority substituents suffix forms are used for radicofunctional nomenclature.

Rules for HC Nomenclature

1. Identify the parent chain

2. Identify the bond type infix

3. Identify suffixable substituents

4. Identify substituents to prefix

5. Indicate the proper locants on the parent

6. Assemble using thee IUPAC format