ORG CHEM | Hydrocarbons

Hydrocarbons

They are compounds that only contain carbon and hydrogen. It usually has the formula C_xH_y, and they are mostly colorless gases with minimal odors (though they can be solid and liquid).

States of Matter of Hydrocarbons

Small alkanes are gases at room temperature while larger alkanes can be liquids or solids based on the chain length.

Boiling and Melting Points of Hydrocarbons

Alkanes have low boiling and melting points due to weak van der waals forces. However molecular mass increases as boiling points increase. Branched alkanes also have lower boiling points due to decreased surface area and weaker van der Waals interactions.

Combustion

Hydrocarbons react with oxygen gas to proudce carbon dioxide, water, and energy.

Cracking

Larger hydrocarbons are broken down into smaller, more useful ones through applying heat, pressure, or a catalyst. This is usually used for producing gasoline or diesel.

Carotenes

a hydrocarbon pigment found in plants like carrots and green leaves, they also make up a large percentage of natural rubber.

Alipatic/acyclic Hydrocarbons

straight or branched chains with no rings

Saturated Hydrocarbons

Also known as alkanes, they consist of only single bonds between carbon atoms, which are all sp³ hybridized. They have the simplest structure and are non-reactive under normal conditions. They are usually used as fuel, such as ethane, propane, butane, and methane in natural gas.

Formula of Saturated Hydrocarbons

C_nH_2n+2

Unsaturated Hydrocarbons

They have at least one double or triple bonds. These bonds make them more chemically reactive

Alkenes

The have at least one double bond between carbon atoms, which are sp² hybridized. They are usually used in the creation of plastics, polymers, and rubber, such as ethylene or ethene. Ethene is released by bananas to speed up the ripening process.

General Formula of Alkenes

C_nH_2n

Alkynes

The have at least one triple bond between carbon atoms, which are sp hybridized. They are usually used in metal work and fruit preservation, such as ethyne.

General Formula of Alkynes

C_nH_2n-2

Alicyclic Hydrocarbons

The carbon atoms are arranged in a ring. These are usually used in pharmaceutical engineering.

Homocyclic

The ring is made up of solely carbon atoms

Resonance

a quality some molecules have wherein the electrons are not fixed in a certain location but can move and “spread out” across several atoms, providing stability

Aromatic Compounds

They have alternating single and double bonds, which provide extra stability due to resonance.

Benzene

With the formula C₆H₆, each of the six carbon atoms in the ring have a hydrogen atom attached. It is considered a pollutant and carcinogen.

Cycloalkanes

These are non-aromatic compounds that do not have the resonance structure due to only being made out of single bonds, but still have rings. They have a general formula of C_nH_2n.

Anti-Aromatic

They do not follow the rules of aromaticity and are less stable.

Heterocyclic Hydrocarbons

at least on atom in the ring is not a carbon