Classification Organic Compounds - Definition, Examples, Structure, Properties, FAQs

Classification Organic Compounds - Definition, Examples, Structure, Properties - FAQs

Edited By Team Careers360 | Updated on Jul 02, 2025 04:46 PM IST

Classification of Organic compounds

Classification of organic compounds is mainly based on their structure and based on the functional group present on them. An organic compound contains carbon, hydrogen and oxygen.

What are organic compounds?

Organic compound definition- The organic compounds are classified as the compounds which contain only two chemical elements, one is carbon and other is hydrogen.

Compound meaning in tamil

Compound meaning in tamil is kalavai கலவை, Organic meaning in Tamil is கரிம, Organic compounds meaning in Hindi is कार्बनिक यौगिक

Also read -

This Story also Contains

Classification of Organic compounds
What are organic compounds?
Organic Compounds Examples
Cyclic Compounds, Ring Compounds or Closed Chain Compounds
Benzenoid aromatic compounds
Non-Benzenoid aromatic compounds
Heterocyclic compounds classification
Acyclic or open chain compounds
Classification of organic compounds based on the functional group

Organic meaning or Organic chemistry definition and examples.

Organic definition-Organic compounds contain carbon as essential constituents.

Organic chemistry meaning- Organic chemistry is a special branch of chemistry that deals with the study of compounds containing carbon. An organic compound contains carbon and hydrogen. Carbon is an element containing 4 valencies so that it can form 4 bonds with other bonds through covalent bonding. Carbon mostly forms compounds with hydrogen so it is also given the name hydrocarbons. The name organic chemistry is given because all of the carbon-containing compounds were considered to have originated from living organisms. One of the very important definitions of organic chemistry is that it is a branch of chemistry that involves the compounds containing carbon and they are found in living beings.

Organic synonyms

Biological, cellular, living, essential, original, live etc.

Organic matter meaning

Organic matter contains large amounts of carbon compounds present in natural environment.

First synthesized organic compound

The first organic compound synthesized in the laboratory was urea by a German chemist named Friedrich Wohler from ammonium cyanate.

Organic Compounds Examples

Some of the common examples of organic compounds are carbohydrates, liquids, proteins, nucleotides, nucleic acids, alkaloids, nutrients such as vitamin B12, etc. Due to the ability to form a carbon-hydrogen bond is easy there are millions of organic compounds are known. The valency of carbon is 4 and thereby it can form 4 bonds with hydrogen. One of the very common examples is methane. The bond formation in methane is shown below.

Bond formation of methane

Classification of organic compounds based on structure

There are millions of organic compounds are present so their classification should be in detail also. The classification following is based on the structure.

Classification of organic compounds based on structures.

Organic compounds are mainly classified into cyclic compounds and acyclic compounds. The cyclic compounds are again classified into homocyclic and heterocyclic compounds. The homocyclic compounds can be again classified as aromatic compounds and aliphatic compounds. Acyclic compounds or open chain compounds can also be again classified as straight-chain compounds and branched-chain compounds.

Also Read:

Cyclic Compounds, Ring Compounds or Closed Chain Compounds

The carbon atoms which are joined together to form a ring are known as ring compounds or cyclic compounds. And which is formed when three or more atoms are connected. The very common example is cyclopropane which contains three carbon atoms joined together to form a triangular-like compound. The following figure shows the structure of these compounds.

Structure of cyclopropane, cyclobutane and cyclohexane.

These cyclic compounds are again classified into homocyclic and heterocyclic compounds.

Homocyclic Compounds

When the compounds contain only carbon atoms it is homocyclic. Cyclopropane, cyclobutene, cyclopentane, cyclohexane, etc. are all examples of homocyclic species. It does not contain an element other than carbon atoms. Homocyclic compounds can be further classified into aromatic and aliphatic compounds.

Alicyclic Compounds

These are aliphatic and cyclic compounds. They may be saturated or unsaturated. The bonds present on them are single, double, and triple bonds. Cyclopropane, cyclobutene, etc. are some examples.

Aromatic Compounds

NEET Highest Scoring Chapters & Topics

This ebook serves as a valuable study guide for NEET exams, specifically designed to assist students in light of recent changes and the removal of certain topics from the NEET exam.

Download EBook

These are cyclic compounds, unlike alicyclic compounds they are unsaturated only. These compounds are called aromatic compounds since they contain a pleasant aroma. Benzene is the most common example. Aromatic compounds possess greater stability due to the presence of conjugated double bonds. It is further classified as benzenoid and non-benzenoid aromatic compounds.

Benzene structure

Benzenoid aromatic compounds

These are aromatic compounds that contain one or more benzene rings that may be isolated or fused. Based on the number of rings present it is further classified into monocyclic with one ring, bicyclic with two rings, and tricyclic with three rings. Some of the common examples include naphthalene, anthracene, phenanthrene, etc. The structure of some of these compounds is shown below.

structure of naphthalene

Structure of anthracene

Non-Benzenoid aromatic compounds

These are aromatic compounds that contain unsaturated rings other than benzene. Examples include azulene, oxa azulanones, tropolone, etc.

Related topics link,

Heterocyclic compounds classification

These are also cyclic compounds but they contain at least one element other than a carbon atom. Mostly the elements are oxygen, nitrogen, and sulfur. Some of the examples of heterocyclic compounds are tetrahydrofuran, oxirane, thietane, pyridine, pyrrole is examples of heterocyclic species. The structure of some of them is shown below.

Oxirane, thietane, tetrahydrofuran, oxazoline, 1, 3-dioxepane, oxetan-2-one

These heterocyclic compounds are further classified into alicyclic heterocyclic compounds and aromatic heterocyclic compounds.

Alicyclic heterocyclic compounds

Heteroatoms like sulfur, oxygen, nitrogen, etc. attached to alicyclic rings are alicyclic heterocyclic compounds. Tetrahydrofuran, tetrahydrothiophene are some examples.

Aromatic heterocyclic compounds

Heteroatoms like sulfur, oxygen, nitrogen, etc. attached to an aromatic ring are aromatic heterocyclic compounds. Thiophene, furan, etc. are some of the examples.

Acyclic or open chain compounds

Here the carbon atoms are arranged in such a way that an open chain or acyclic compound is formed. These are also known as aliphatic compounds. Those chains present on them may be branched or straight chains. Based on that it can be further divided into two types that is straight-chain organic compounds and branched-chain organic compounds.

Straight chain Organic compounds

The carbon atoms arranged in such a way that it forms a straight chain. In naming those compounds the letter ‘n’ is used which represents normal. Some of the examples of which include n-propane, n-butane, n-pentane, etc. When it contains double bonds they are named propene, butene, etc.

Branched-chain organic compounds

For branched-chain organic compounds, their carbon skeleton contains a branched-chain. The name ‘iso’ is used to notate. Some of the examples are isobutane, iso propane, isopentane, etc. When double bonds came it is named as isobutylene, iso propylene, etc.

Classification of organic compounds based on the functional group

Organic compounds can again be classified based on functional group and mainly explains the chemical behavior of organic compounds. The property of organic compounds changes with changing functional groups attached to them. There are many functional groups which include hydroxyl group, carboxyl group, amino group, cyano group, etc. These are explained in detail below given table.

Class	Functional group
Alcohols	-OH
Carboxylic acid	-COOH
Isocynides	-NC
Ketones	Carbonyl
Nitro compounds	NO^-₂
Cyanides	Cyano
Aldehyde	-CHO

Based on the presence of functional group name, properties, chemical behavior, odor, color, reaction, etc. of organic compounds will change. When the hydroxyl group is present the organic compound will be alcoholic and the ‘ol’ will be used. Examples are propanol, butanol, etc.

Also check-

NCERT Chemistry Notes:

Frequently Asked Questions (FAQs)

1. Which is an organic compound found in most cells?

The organic compound found in most cells is glucose.

2. What is an alicyclic compound?

Saturated or unsaturated aliphatic cyclic compounds are alicyclic compounds.

3. What is organic meaning in english?

Organic means the compound that has carbon.

4. What is meant by organic chemistry?

Organic chemistry mainly focuses on the properties like structure, reaction, composition, synthesis, etc. In addition to carbon and hydrogen, organic compounds contain nitrogen, oxygen, halogens, and rarely sulfur and phosphorus. The field of organic chemistry is also so broad, some of which include green chemistry, fullerene chemistry, chiral synthesis, polymer chemistry, stereochemistry, etc.

5. Founder of organic chemistry?

Friedrich Wohler.

6. Examples for alicyclic compounds?

Cyclopropane, cyclobutane, cyclopentane, cyclohexane, etc.

7. Which is not an organic acid?

Carbonic acid, because it does not contain C-H bonds.

8. Organic compounds will always contain?

Carbon.

9. What is an organic substance?

Carbon allotropes, bicarbonates, carbides, carbonates, cyanides, etc. are organic substances.

10. Write the formula of an organic compound contains carbon hydrogen and oxygen.

CHO

11. What role do substituents play in determining the properties of organic compounds?

Substituents are atoms or groups that replace hydrogen atoms in a parent hydrocarbon. They play a crucial role in determining properties like solubility, boiling point, and reactivity of organic compounds. Substituents can be electron-withdrawing or electron-donating, affecting the electron distribution in the molecule and thus its chemical behavior.

12. How do cyclic compounds differ from their acyclic counterparts?

Cyclic compounds contain rings of atoms, while acyclic compounds have open chains. This structural difference affects properties like boiling point, melting point, and reactivity. Cyclic compounds often have higher melting and boiling points due to stronger intermolecular forces. They can also exhibit different reactivity patterns, especially in ring-opening or ring-closing reactions.

13. What is the importance of understanding stereochemistry in organic compounds?

Stereochemistry deals with the three-dimensional arrangement of atoms in molecules. It's crucial because the spatial arrangement of atoms can significantly affect a compound's properties and reactivity. Stereochemistry is particularly important in biological systems, where enzymes and receptors often interact with only specific stereoisomers of a compound.

14. How does the concept of hybridization relate to the structure and properties of organic compounds?

Hybridization describes the mixing of atomic orbitals to form new hybrid orbitals, which explains the geometry and bonding in molecules. It's crucial for understanding the three-dimensional structure of organic compounds, bond angles, and reactivity. For example, sp3 hybridization in alkanes results in tetrahedral geometry, while sp2 hybridization in alkenes leads to planar structures with 120° bond angles.

15. How do alkenes and alkynes differ in their reactivity?

Alkenes (compounds with carbon-carbon double bonds) and alkynes (compounds with carbon-carbon triple bonds) differ in their reactivity due to the nature of their multiple bonds. Alkynes are generally more reactive than alkenes because the triple bond is more electron-rich. However, both undergo addition reactions, with alkynes capable of adding more atoms or groups due to their higher degree of unsaturation.

16. How does the presence of a benzene ring affect an organic compound's properties?

The presence of a benzene ring, which is a cyclic arrangement of six carbon atoms with alternating single and double bonds, gives organic compounds unique properties. These aromatic compounds are generally more stable and less reactive than similar non-aromatic compounds due to the delocalization of electrons in the ring structure.

17. What is the importance of understanding radical reactions in organic chemistry?

Radical reactions involve species with unpaired electrons and often proceed through different mechanisms than ionic reactions. They are important in many industrial processes, polymerizations, and biological systems (like lipid oxidation). Understanding radical chemistry is crucial for explaining certain reaction outcomes, designing new synthetic methods, and understanding processes like autoxidation and free radical damage in biological systems.

18. How do neighboring group effects influence reactivity in organic compounds?

Neighboring group effects occur when a functional group in a molecule influences the reactivity of a nearby group. These effects can dramatically alter reaction rates and product distributions. Understanding neighboring group participation is crucial for predicting reaction outcomes, especially in carbohydrate and steroid chemistry, where it can lead to unexpected stereochemical results.

19. What is the importance of understanding stereoselectivity in organic reactions?

Stereoselectivity refers to the preferential formation of one stereoisomer over another in a reaction. It's important because many biological processes and pharmaceutical effects are stereospecific. Understanding and controlling stereoselectivity is crucial in drug synthesis, where producing the correct stereoisomer can mean the difference between an effective medicine and a harmful compound.

20. What is the significance of understanding rearrangement reactions in organic chemistry?

Rearrangement reactions involve the reorganization of atoms within a molecule, often leading to unexpected products. Understanding these reactions is crucial because they can occur unexpectedly in many synthetic processes, affecting yield and product distribution. Rearrangements are also important in biological systems and can be exploited in synthetic strategies to create complex molecules efficiently.

21. What distinguishes aliphatic from aromatic compounds?

Aliphatic compounds are characterized by open-chain or cyclic structures of carbon atoms without aromatic rings. Aromatic compounds, on the other hand, contain at least one benzene ring or similar structure with delocalized electrons. This distinction is important because aromatic compounds exhibit unique stability and reactivity patterns compared to their aliphatic counterparts.

22. What is the importance of IUPAC nomenclature in classifying organic compounds?

IUPAC (International Union of Pure and Applied Chemistry) nomenclature provides a standardized system for naming organic compounds. It's important because it allows chemists worldwide to communicate unambiguously about specific compounds. The name of a compound in IUPAC nomenclature provides information about its structure, functional groups, and sometimes its properties, aiding in classification and understanding.

23. What is the significance of homologous series in organic chemistry?

A homologous series is a group of organic compounds with similar chemical properties due to the presence of the same functional group, differing only by the number of -CH2- units in their carbon chain. This concept is significant because it allows chemists to predict properties and reactions of compounds within the same series, simplifying the study of organic chemistry.

24. What is the significance of tautomerism in organic compounds?

Tautomerism is a type of structural isomerism where compounds exist in equilibrium between two or more structures that differ in the position of a proton and a π bond. It's significant because tautomers can have different reactivity and properties. Understanding tautomerism is crucial in predicting reaction outcomes and interpreting spectroscopic data.

25. What is the primary basis for classifying organic compounds?

The primary basis for classifying organic compounds is their functional groups. Functional groups are specific arrangements of atoms within molecules that give the compound characteristic chemical properties. These groups determine how the molecule will react with other substances and are essential for understanding organic chemistry.

26. How do hydrocarbons differ from other organic compounds?

Hydrocarbons differ from other organic compounds in that they contain only carbon and hydrogen atoms. They lack any other elements or functional groups, making them the simplest class of organic compounds. All other organic compounds are derived from hydrocarbons by adding or replacing atoms with various functional groups.

27. What is the difference between saturated and unsaturated compounds?

Saturated compounds contain only single bonds between carbon atoms, while unsaturated compounds have at least one double or triple bond between carbon atoms. This difference affects their reactivity, with unsaturated compounds generally being more reactive due to the presence of multiple bonds.

28. What role do heteroatoms play in organic compounds?

Heteroatoms are atoms other than carbon and hydrogen in organic compounds, such as oxygen, nitrogen, sulfur, or halogens. They play a crucial role in determining the compound's properties and reactivity. Heteroatoms often form part of functional groups and can significantly influence the compound's polarity, acidity, basicity, and overall chemical behavior.

29. How does the concept of isomerism relate to the classification of organic compounds?

Isomerism refers to compounds with the same molecular formula but different structural arrangements. This concept is important in classifying organic compounds because isomers can have vastly different properties and reactivities despite having the same elemental composition. Understanding isomerism helps in predicting and explaining the behavior of organic compounds.

30. How does ring strain affect the properties and reactivity of cyclic compounds?

Ring strain refers to the instability in cyclic compounds due to bond angles deviating from ideal tetrahedral geometry. It significantly affects the reactivity and properties of cyclic compounds. Highly strained rings, like cyclopropane, are more reactive and prone to ring-opening reactions. Understanding ring strain is crucial for predicting the behavior of cyclic compounds in various reactions and their overall stability.

31. How do conformational changes affect the properties of organic compounds?

Conformational changes refer to rotations around single bonds that don't change the overall structure but can affect the molecule's shape. These changes can significantly impact a compound's reactivity, stability, and physical properties. For example, different conformations of cyclohexane have different energies and reactivities. Understanding conformations is crucial in fields like drug design, where a molecule's shape affects its biological activity.

32. What is the significance of chirality in organic compounds?

Chirality refers to the property of a molecule that is non-superimposable on its mirror image. It's significant in organic chemistry because chiral molecules can have different biological activities despite having the same chemical formula and similar structures. This concept is crucial in pharmaceutical chemistry, where different enantiomers (mirror-image forms) of a drug can have vastly different effects on the body.

33. How do aromatic heterocycles differ from carbocyclic aromatic compounds?

Aromatic heterocycles contain one or more heteroatoms (like N, O, S) in their ring structure, while carbocyclic aromatic compounds contain only carbon atoms in the ring. This difference affects their electronic properties, reactivity, and basicity. Heterocycles are common in biological molecules and pharmaceuticals, often exhibiting unique properties due to the presence of heteroatoms.

34. What is the importance of understanding oxidation states in organic chemistry?

Understanding oxidation states in organic chemistry is important for predicting and explaining redox reactions. It helps in identifying which atoms are oxidized or reduced in a reaction, which is crucial for understanding metabolic processes, synthetic strategies, and the behavior of organic compounds in various environments. Oxidation state changes often correlate with changes in functional groups.

35. What is the significance of understanding pKa values in organic chemistry?

pKa values indicate the strength of an acid and are crucial for predicting acid-base reactions, solubility, and reactivity of organic compounds. Understanding pKa helps in determining which compounds will act as acids or bases in a given situation, which is essential for predicting reaction outcomes and designing synthetic strategies. It's also important in understanding buffer systems and pH-dependent processes in biological systems.

36. What is the importance of understanding reaction mechanisms in organic chemistry?

Understanding reaction mechanisms is crucial because it allows chemists to predict the outcomes of reactions, explain why certain products form, and design new synthetic routes. Mechanisms provide insight into how bonds break and form, how electrons move, and what factors influence reaction rates and selectivity. This knowledge is essential for developing new drugs, materials, and chemical processes.

37. What is the significance of understanding frontier molecular orbitals in organic reactions?

Frontier molecular orbitals (HOMO and LUMO) play a crucial role in determining the reactivity and selectivity of organic reactions. The interaction between the HOMO of one reactant and the LUMO of another often determines whether and how a reaction will proceed. This concept is fundamental in explaining pericyclic reactions, understanding UV-visible spectroscopy, and predicting reactivity patterns in organic synthesis.

38. What is the significance of aromaticity in organic compounds?

Aromaticity is a property of cyclic, planar molecules with a special electron configuration that gives them enhanced stability. Aromatic compounds are significantly more stable than similar non-aromatic compounds, affecting their reactivity. They tend to undergo substitution rather than addition reactions. Understanding aromaticity is crucial for predicting the behavior of many important organic compounds, including many biological molecules.

39. How does the concept of resonance apply to organic compound classification?

Resonance is a way of describing delocalized electrons in molecules where multiple legitimate Lewis structures can be drawn. It's important in classifying organic compounds because resonance structures often explain a compound's stability, reactivity, and properties. Compounds with resonance, like benzene and carboxylate ions, often behave differently from what might be expected based on a single Lewis structure.

40. What is the significance of conjugation in organic compounds?

Conjugation refers to the interaction of p-orbitals in a system of alternating single and multiple bonds. It's significant because conjugated systems often have unique properties, including color (as in dyes), conductivity, and enhanced stability. Conjugation can lower the energy of the molecule, affecting its reactivity and spectroscopic properties.

41. What is the importance of understanding molecular orbital theory in organic chemistry?

Molecular orbital theory provides a more accurate description of bonding in molecules than valence bond theory. It's important for understanding concepts like conjugation, aromaticity, and pericyclic reactions. This theory helps explain spectroscopic properties, reactivity patterns, and the stability of various organic compounds, especially those with delocalized electrons.

42. How do protecting groups influence the synthesis of complex organic molecules?

Protecting groups are temporary modifications to functional groups that prevent unwanted reactions at specific sites during multi-step syntheses. They are crucial in the synthesis of complex molecules, allowing chemists to selectively modify one part of a molecule while leaving other reactive groups untouched. Understanding protecting group chemistry is essential for planning and executing complex organic syntheses, particularly in the pharmaceutical industry.

43. How does hydrogen bonding affect the physical properties of organic compounds?

Hydrogen bonding, a strong intermolecular force between a hydrogen atom bonded to a highly electronegative atom (like O, N, or F) and another electronegative atom, significantly affects physical properties. It increases boiling points, melting points, and solubility in water. Compounds capable of hydrogen bonding, like alcohols and carboxylic acids, often have unexpectedly high boiling points for their molecular weight.

44. How do polymers differ from their monomer units in terms of properties?

Polymers are large molecules composed of repeating subunits (monomers). They differ from their monomers in several ways: polymers typically have higher melting and boiling points, greater strength and durability, and different solubility properties. The properties of polymers depend not only on their chemical composition but also on their molecular weight, degree of branching, and intermolecular forces between polymer chains.

45. How do organometallic compounds differ from typical organic compounds?

Organometallic compounds contain bonds between carbon and metal atoms. They differ from typical organic compounds in their reactivity, often being much more reactive due to the polarized nature of the carbon-metal bond. Organometallic compounds play crucial roles as catalysts in many industrial processes and synthetic reactions, allowing for transformations that would be difficult or impossible with traditional organic reagents.

46. How does electronegativity influence the properties of organic compounds?

Electronegativity, the ability of an atom to attract electrons in a chemical bond, greatly influences organic compound properties. It affects bond polarity, which in turn impacts intermolecular forces, solubility, and reactivity. Highly electronegative atoms like oxygen or nitrogen in functional groups can make parts of molecules polar, influencing their behavior in reactions and their physical properties.

47. How do functional groups influence the solubility of organic compounds?

Functional groups greatly influence the solubility of organic compounds by affecting their polarity and ability to form hydrogen bonds. Polar functional groups (like -OH, -COOH) increase water solubility, while non-polar groups (like long hydrocarbon chains) decrease it. The balance between polar and non-polar portions of a molecule determines its overall solubility in different solvents.

48. How does the presence of a carbonyl group affect an organic compound's reactivity?

The carbonyl group (C=O) significantly affects an organic compound's reactivity due to its polar nature and the partial positive charge on the carbon atom. This makes carbonyl compounds prone to nucleophilic addition reactions. The carbonyl group's presence also influences the acidity of nearby hydrogen atoms, enabling various reactions like aldol condensations in aldehydes and ketones.

49. What is the importance of understanding acid-base behavior in organic compounds?

Understanding acid-base behavior is crucial because many organic reactions involve proton transfer. The acidity or basicity of organic compounds depends on their structure and functional groups. This knowledge helps predict reactivity, solubility, and other properties. For example, carboxylic acids are more acidic than alcohols due to the stabilization of the conjugate base by resonance.

50. How does the presence of multiple functional groups affect the properties and reactivity of organic compounds?

When multiple functional groups are present in an organic compound, they can interact with each other, leading to unique properties and reactivity. These interactions can enhance or diminish the typical behaviors of individual functional groups. For example, in amino acids, the presence of both amine and carboxylic acid groups leads to zwitterion formation, affecting solubility and acid-base properties.

51. How do solvent effects influence organic reactions?

Solvents can significantly affect the rate, yield, and even the outcome of organic reactions. They influence the stability of reactants, products, and transition states through solvation effects. Polar solvents can stabilize charged species, while non-polar solvents favor uncharged molecules. Understanding solvent effects is crucial for optimizing reaction conditions and explaining observed reactivity patterns.

52. How do leaving groups affect the reactivity in substitution and elimination reactions?

Leaving groups are atoms or molecules that depart during substitution or elimination reactions. The ability of a group to leave (its leaving group ability) significantly affects reaction rates and mechanisms. Good leaving groups are typically weak bases and form stable species upon departure. Understanding leaving group effects is crucial for predicting reaction outcomes and designing efficient synthetic routes.