Alkanes and Alkenes Overview

Study Notes

Alkanes

Alkanes are saturated hydrocarbons, meaning they contain only single bonds between carbon atoms.
They are the simplest class of organic compounds.
The general formula for alkanes is C_nH_2n+2, where 'n' represents the number of carbon atoms.
Alkanes are relatively unreactive due to the strength of the carbon-hydrogen and carbon-carbon single bonds.
They are primarily characterized by their ability to undergo combustion reactions with oxygen to produce carbon dioxide and water.
Methane (CH₄), ethane (C₂H₆), propane (C₃H₈), butane (C₄H₁₀) and pentane (C₅H₁₂) are examples of alkanes.
Alkanes are typically nonpolar, which makes them insoluble in water.
Increasing chain length leads to increasing boiling points and melting points.
Branched alkanes have lower boiling points than their straight-chain isomers.

Alkenes

Alkenes are unsaturated hydrocarbons containing at least one carbon-carbon double bond.
The general formula for alkenes is C_nH_2n.
The presence of a double bond makes alkenes more reactive than alkanes.
They undergo addition reactions, where atoms or groups of atoms add across the double bond.
Examples of alkenes include ethene (C₂H₄), propene (C₃H₆), and but-1-ene (C₄H₈)
The double bond creates geometric isomers: cis-trans isomers are possible depending on the arrangement of substituents around the double bond.
The presence of a double bond affects the physical properties.

Carboxylic Acids

Carboxylic acids are organic compounds containing a carboxyl functional group (-COOH).
The general formula for carboxylic acids is C_nH_2nO₂.
Carboxylic acids are typically polar, and have the ability to form hydrogen bonds with other molecules in the same and other groups.
They tend to have higher boiling points than comparable alkanes and alkenes due to their ability to hydrogen bond, thus causing higher intermolecular forces.
They are weak acids.
Carboxylic acids are often found in many natural sources and contribute to the flavors and fragrances of many foods and essential oils.
Examples include formic acid (HCOOH), acetic acid (CH₃COOH), propanoic acid (C₂H₅COOH).

Esters

Esters are organic compounds derived from the reaction between a carboxylic acid and an alcohol.
The reaction is called esterification.
They are characterized by the ester functional group (-COO-), which is formed between the carbonyl carbon of a carboxylic acid and an oxygen atom of an alcohol.
Esters often have pleasant, fruity aromas, which have contributed to their use in fragrances and flavorings.
The general naming of an ester involves naming the alkyl part of the alcohol first followed by the alkyl part of the carboxylic acid with the ending changed to -oate.
Examples include methyl acetate (CH₃COOCH₃), ethyl propanoate (CH₃CH₂COOCH₂CH₃).
Esters are typically less polar than carboxylic acids.
Esters are common in fats and oils; these are triglycerides, esters of glycerol and fatty acids.
Esters are often less soluble in water than carboxylic acids, owing to their lower polarity and reduced ability to form hydrogen bonds.

Description

This quiz covers the fundamental concepts of alkanes and alkenes, including their structures, reactions, and properties. Learn about their general formulas, examples, and how their molecular structure affects their physical properties. Perfect for students studying organic chemistry.