Organic Chemistry - Hydrocarbons

Definition

The study of organic chemistry is the study of the chemistry of carbon compounds. Not all carbon compounds are counted as organic, the rule excludes carbonates (x-CO₃), carbon monoxide (CO) and carbon dioxide (CO₂).
Hydrocarbons contain hydrogen (H) and carbon only. They are divided into groups such as alkanes, alkynes, alkenes and alcohols, and are homologous series. Homologous series are, accodring to tiscali.co.uk, “any of a number of series of organic compounds with similar chemical properties in which members can be described by a general formula and ofen differ by a constant relative molecular mass”.

Alkanes

Alkanes are, thanks to their purely single carbon bonds (C-C), saturated. Physical properties include low melting- and boiling points considering the molar mass. They do not conduct, have low densities and do not solve in water.

Examples

• Methane - CH₄
• Ethane - C₂H₆
• Propane - C₃H₈
• Butane - C₄H₁₀
• Pentane - C₅H₁₂
• Hexane - C₆H₁₄

Alkenes

Alkenes have one double carbon bond (C=C), and as they have at least one double bond they are unsaturated. Physical properties include the appearance; ranging from colorless gas to black solids, the non-conductivity, the low melting- and boiling points, the low densities, the insolubility in water and the volatility - as alkenes react rather much due to their double bond (resulting in either combustion or addition).
Examples of addition can be found when mixing an alkene (or any other unsaturated hydrocarbon) with Bromine water. When shaken, unsaturated hydrocarbons decolorize the solution.
Also, ethene forms ethanol when reacted with water, essentially saturating the unsaturated hydrocarbon. This process is often used in margarine production, to state an example.

Examples

• Ethene - C₂H₄
• Propene - C₃H₆
• Butene - C₄H₈

Alcohols

Physical properties of alcohols include liquid state at room temperature, rather high volatility (resulting in combustion), lack of color, low melting- and boiling points, low densities (compared to water) and a lack of conductivity.
Among the chemical properties one finds a low reactivity. The uses for alcohols are in beverages and foods as well as in fuel and disinfectors.
Alcohols are made using two different processes - fermentation of sugar and hydration of ethene.
The process of fermentation is to convert glucose sugar (C₆H₁₂O₆) into alcohol (CH₃CH₂OH) and carbon dioxide (CO₂) - essentially adding yeast to sugar.
The process of hydrating ethene is to add water in a gaseous form (H₂O) to ethene (C₂=C₂), also in a gaseous form. Ethene is mixed with the water steam and passed over a catalyst consisting of solid silicon dioxide coated with phosphoric(V) acid, all under a pressure of 60-70 atmospheres and a temperature of nearly 300°C.

Examples

• Methanol - CH₃OH
• Ethanol - CH₅OH (or CH₃CH₂OH)
• Propanol - CH₇OH (or CH₃CH₂CH₂OH)