Organic Compounds and Hydrocarbon Functional Groups

Oil, gas and petrochemical products consist of various organic compounds. All of organic compounds share an extraordinary element. Carbon is the element that plays an important role in characterizing these compounds. One vast subset of organic compounds are hydrocarbons. Hydrocarbons exclusively consists of carbon and hydrogen atoms. Other important elements usually exist in organic molecule’s structure are oxygen, sulfur and nitrogen. The characteristics and chemical behaviors of an organic compound is defined by its functional group. In organic chemistry, functional groups are combinations of specific elements connected together in a particular manner. In the following section, we will study some well-known organic compounds and significant functional groups that are so famous in oil and gas industry.

Alkane, traditionally called paraffin, is a saturated hydrocarbon in which all carbon-carbon bonds are single. Their most important commercial sources are either petroleum or natural gas.

Example: Methane (CH₄) which is the smallest alkane.

Methane

Alkene / (ˈælkiːn) /, traditionally called olefin, is a hydrocarbon that contains carbon-carbon double bond. They can be converted to polyolefin to form polymers.

Example: ethylene, also known as ethene, (C₂H₄) is the smallest alkene.

Ethylene

Alkyne / (ˈælkaɪn) / is an unsaturated hydrocarbon containing at least one carbon-carbon triple bond.

Example: Acetylene, also known as ethyne, (C₂H₂) which has one of the greatest heating value mostly used in welding applications and portable lights.

Acetylene

Aromatic may refer to every organic compound which has “pi bounds” in resonance with a planar structure. Due to its structure, it has a strong stability.

Example: Benzene (C₆H₆)

Benzene

Aliphatic is a non-aromatic organic compound.

Example: Cyclohexane (C₆H₁₂)

Cyclohexane

Naphthene is an aliphatic cyclic saturated hydrocarbon. It consists of only carbon and hydrogen atoms.

Example: Cyclopentane (C₅H₁₀)

Cyclopentane

In organic chemistry, an alkyl substituent is an alkane missing one hydrogen. Alkyl can be connected to other molecules to form a larger organic compound. The smallest alkyl group is methyl (CH₃−).

In organic chemistry, an aryl is any functional group or substituent derived from an aromatic ring, usually an aromatic hydrocarbon. Aryl can be connected to other molecules to form a larger organic compound. The simplest aryl group is phenyl (C₆H₅). Phenyl is derived from benzene by losing one hydrogen atom.

Alcohols are organic compounds with hydroxyl group (-OH). Because of hydroxyl group, they are polar compounds and more water-soluble than simple hydrocarbons. They also tend to have higher boiling point than most hydrocarbons due to the hydrogen bonding.

Example: Methanol, also called methyl alcohol, (CH₃OH) is the simplest alcohol.

Methanol

Carboxylic acids are organic acids contain a carboxyl group (C(=O)OH), with R referring to the alkyl group.

Examples: Formic acid, also called methanoic acid, (HCOOH) is the simplest carboxylic acid.

Formic acid

Ether functional group consists of an oxygen atom connected to two alkyl or aryl groups with a general formula of (R–O–R′).

Example: Dimethyl ether, also called methoxymethane, (CH₃OCH₃)  is the simplest ether.

Dimethyl ether

Ketone is a hydrocarbon functional group contains a carbonyl group (R₂C=O), where R is a carbon containing substituents.

Example: Acetone (CH₃)₂CO which is the simplest ketone.

Acetone

Aldehyde ia usually created by removing hydrogen from an alcohol. It is a compound containing a functional group with the structure of (−CHO).

Example: Formaldehyde (CH₂O) which is the simplest aldehyde. It is mostly used as a precursor to industrial resin and adhesive.

Formaldehyde

Ester is derived from an acid in which the hydrogen of hydroxyl group (–OH) substitutes by carbon.

Example: Methyl formate, also known as M-formate or methyl methanoate, (C₂H₄O₂) is the simplest ester. It is the methyl ester of formic acid.

Methyl formate

Amide is a compound with the general formula (RC(=O)NR′R″), where R, R’, and R″ represent organic groups or hydrogen atoms. Amide can be converted to polyamide which is a precursor to nylons or proteins.

Example: Formamide, also known as methanamide, (CH₃NO) is derived from formic acid.

Formamide

Thiol, also called mercaptan, is a sulfur analogue of alcohols. Thiol has a general formula of (R−SH), where R represents an alkyl or other organic molecules. Main characteristic is that they have strong odor. They are also harmful to steel structures and may cause sulfur stress cracking.

Example: Methyl mercaptan. also known as methanethiol (CH₃SH)

Methyl mercaptan

Diol, is a functional group consists of two hydroxyl groups (−OH). An aliphatic diol is also called glycol.

Example: Ethylene glycol (CH₂OH)₂

Ethylene glycol

Amine is a compound that contains a nitrogen atom with a pair of valance electrons that are not shared with another atom in a covalent bond (unshared pair). Amines are the derivatives of ammonia. They consist of the general formula of (:NRR’R”), where R, R’, and R″ represent organic groups such as an alkyl or aryl. R’ and R” can also be hydrogen atoms. Amines can be both organic and inorganic. Amino acids, which are the building blocks of proteins, contain amines and carboxyl functional groups.

Example: Trimethylamine (TMA) that is an organic amine with a formula of N(CH₃)₃

Trimethylamine