3.7
Organic Compounds
All living things are formed mostly of carbon compounds called organic compounds. The category of organic compounds includes both natural and syntheti…
Chemical compounds composed primarily of carbon atoms bonded to hydrogen, oxygen, nitrogen, or sulfur atoms are called organic compounds.
Organic compounds form a vast variety of molecules — from fundamental building blocks of life like DNA or plant cell walls to energy liberating materials like fuels. They are usually easily broken down.
Carbon atoms constitute the backbone of every organic compound, which can assume diverse structures with ring-shaped, branched, and straight-chain arrangements due to carbon’s versatility to form four bonds, either as single, double, or triple bonds.
Organic compounds can be either hydrocarbons or functionalized hydrocarbons.
Hydrocarbons are constituted entirely of carbon and hydrogen atoms. Alkanes are hydrocarbons containing single bonds. Alkenes contain one or more double bonds, while alkynes contain one or more triple bonds.
Hydrocarbon nomenclature follows a pattern where the base-name is mentioned first using a prefix determined by the number of carbon atoms. The name ends with the suffix –ane, –ene, or –yne depending on the presence of single, double, or triple bonds, respectively.
For example, the single-bond containing alkane with three carbon atoms is propane. Double-bond containing alkene with three carbons is propene, while a triple-bond containing alkyne with three carbon atoms is propyne.
Hydrocarbons with one or more of its hydrogen atoms substituted by a specific group of atoms or functional groups are called functionalized hydrocarbons. The general formula of functionalized hydrocarbons designates the hydrocarbon portion by the letter ‘R’ and the specific functional group.
Functional groups can be of many types and have specific physical and chemical properties. All organic compounds carrying a common functional group fall under the same family of hydrocarbons, exhibit similar properties and follow similar nomenclature.
For instance, all organic compounds carrying an –OH functional group are called alcohols. The nomenclature mentions the parent-alkane base-name ending with the suffix –ol, specific to the alcohol functional group. Hence, propane having an –OH functional group is named propanol.
In contrast, all organic compounds carrying carboxyl functional groups are called carboxylic acids. The nomenclature states the parent-alkane base-name ending with the suffix –oic acid, unique to the carboxyl functional group. Hence, propane with a carboxyl functional group is named propanoic acid.
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Q1: What are organic compounds and what elements do they contain?
Organic compounds are chemical substances composed primarily of carbon atoms bonded to hydrogen, oxygen, nitrogen, or sulfur atoms. Carbon forms the backbone of every organic compound, enabling the formation of diverse structures including ring-shaped, branched, and straight-chain arrangements. These compounds range from fundamental building blocks of life like DNA to energy-liberating materials like fuels.
Q2: How does carbon's bonding ability create the variety of organic compounds?
Carbon's versatility to form four bonds—either as single, double, or triple bonds—enables the creation of diverse molecular structures. This bonding flexibility allows carbon atoms to connect in chains, rings, and branched configurations, resulting in the vast variety of organic molecules found in nature and synthesized by chemists.
Q3: What is the difference between hydrocarbons and functionalized hydrocarbons?
Hydrocarbons contain only carbon and hydrogen atoms, while functionalized hydrocarbons are hydrocarbons with one or more hydrogen atoms substituted by functional groups—specific groups of atoms that determine chemical and physical properties. Functionalized hydrocarbons are designated using the letter 'R' for the hydrocarbon portion and the specific functional group attached.
Q4: How are alkanes, alkenes, and alkynes different?
Alkanes contain only single bonds between carbon atoms, alkenes contain one or more double bonds, and alkynes contain one or more triple bonds. Hydrocarbon nomenclature reflects these differences: alkanes end in –ane, alkenes end in –ene, and alkynes end in –yne. For example, propane has single bonds, propene has a double bond, and propyne has a triple bond.
Q5: What are functional groups and how do they classify organic compounds?
Functional groups are characteristic atoms or groups of atoms that primarily determine the properties of hydrocarbon derivatives. All organic compounds carrying a common functional group fall under the same family, exhibit similar properties, and follow similar nomenclature patterns. For instance, compounds with –OH groups are alcohols, while those with carboxyl groups are carboxylic acids.
Q6: How is the nomenclature of alcohols and carboxylic acids determined?
Alcohol nomenclature uses the parent-alkane base-name with the suffix –ol replacing the final –e. For example, propane becomes propanol when an –OH group is added. Carboxylic acid nomenclature uses the parent-alkane base-name with the suffix –oic acid. Thus, propane with a carboxyl group becomes propanoic acid.
Q7: What role do carbonyl groups play in organic compound families?
The carbonyl group, a carbon-oxygen double bond, is the key structure in several organic compound families. Aldehydes, ketones, carboxylic acids, and esters all contain carbonyl groups with different substituents attached. These compounds contain oxidized carbon atoms relative to alcohols, and their distinct structures determine their unique chemical properties and nomenclature.