Undergraduate
  1. General chemistry  1.1. Introduction to Chemistry  1.2. Atomic Structure  1.2.1. Subatomic particles  1.2.2. Atomic Model  1.2.3. Quantum numbers  1.2.4. Electron Configuration  1.2.5. Periodic trends  1.2.6. Isotopes and their applications  1.3. Chemical bond  1.3.1. Ionic bond  1.3.2. Covalent bonds  1.3.3. Metal Bond  1.3.4. Hybridization  1.3.5. Molecular geometry and VSEPR theory  1.3.6. Bond polarity and dipole moment  1.4. Stoichiometry  1.4.1. Mole concept  1.4.2. Empirical and molecular formula  1.4.3. Limiting reactant and excess reactant  1.4.4. Percent Yield and Purity  1.4.5. Dilution calculation  1.5. States of matter  1.5.1. Gas Laws  1.5.2. Matter and Intermolecular Forces  1.5.3. Solid and Crystal Structures  1.5.4. Phase diagram  1.5.5. Plasma and supercritical fluid  1.6. Chemical reactions  1.6.1. Types of Chemical Reactions  1.6.2. Balancing Chemical Equations  1.6.3. Thermochemical reactions  1.6.4. Reaction energy profiles  1.7. Solutions and Mixtures  1.7.1. Concentration units  1.7.2. Syndrome properties  1.7.3. Solubility and Solubility Rules  1.7.4. Henry's Law and Raoult's Law  1.7.5. Partition coefficient  1.8. Chemical equilibrium  1.8.1. Law of mass action  1.8.2. Le Chatelier's principle  1.8.3. Reaction quotient  1.8.4. To use this online calculator for Equilibrium Constant, enter Equilibrium Constant (Eq.) and hit the calculate button. Here is how the Equilibrium Constant calculation can be explained with given input values -> 0.05 = 0.05/0.  1.8.5. Acid-base balance  1.9. Acids and bases  1.9.1. Arrhenius, Brønsted–Lowry, and Lewis definitions  1.9.2. pH and pOH  1.9.3. Acid-base titration  1.9.4. Buffer Solution  1.9.5. Acid-base indicator  1.9.6. Polyprotic Acids and Bases  1.10. Electrochemistry  1.10.1. redox reactions  1.10.2. Galvanic and Electrolytic Cells  1.10.3. Nernst equation  1.10.4. Electrolysis  1.10.5. Faraday's laws of electrolysis  1.11. Thermodynamics  1.11.1. Laws of Thermodynamics  1.11.2. Enthalpy, entropy and Gibbs free energy  1.11.3. Spontaneity of reactions  1.11.4. Thermodynamic cycles (Hess's law, Carnot cycle)  1.12. Kinetics  1.12.1. Rate law and reaction order  1.12.2. Activation Energy and Catalyst  1.12.3. Collision theory  1.12.4. Reaction mechanism  1.12.5. Transition state theory
  2. Organic chemistry  2.1. Structure and relationships  2.1.1. Hybridisation in Carbon Compounds  2.1.2. Resonance and aromatization  2.1.3. Molecular orbitals  2.1.4. Inductive and mesomeric effects  2.2. Hydrocarbons  2.2.1. Hydrocarbons  2.2.2. Alkene  2.2.3. Alkynes  2.2.4. Aromatic compounds  2.2.5. Cycloalkanes and Conformation  2.3. Functional Group  2.3.1. Alcohols and phenols  2.3.2. Ethers and epoxides  2.3.3. Aldehyde and ketone  2.3.4. Carboxylic acids and derivatives  2.3.5. Amin  2.3.6. Esters and amides  2.3.7. Thiols and sulfides  2.4. Stereoscopic  2.4.1. Isomerism in Stereochemistry  2.4.2. Chirality and optical activity  2.4.3. Structural analysis  2.4.4. Diastereomers and Enantiomers  2.5.1. Substitution reactions  2.5.2. Elimination reactions  2.5.3. Addition reactions  2.5.4. Radical reactions  2.5.5. Rearrangement reactions  2.5.6. Pericyclic Reactions  2.6. Spectroscopy and structural analysis  2.6.1. Infrared Spectroscopy  2.6.2. Nuclear magnetic resonance spectroscopy  2.6.3. Mass Spectrometry  2.6.4. UV-visible spectroscopy  2.6.5. X-ray crystallography  2.7. Polymer chemistry  2.7.1. Addition and Condensation Polymers  2.7.2. Polymerization mechanism  2.7.3. Biodegradable Polymer  2.7.4. Conducting and smart polymers
  3. Inorganic chemistry  3.1. Coordination chemistry  3.1.1. Ligands and coordination compounds  3.1.2. Crystal field theory  3.1.3. Molecular Orbital Theory in Coordination Compounds  3.1.4. Jahn–Taylor distortion  3.2. Main Group Chemistry  3.2.1. Alkali and alkaline earth metals  3.2.2. Halogens and Noble Gases  3.2.3. Transition metals and their complexes  3.2.4. Lanthanides and Actinides  3.3. Solid state chemistry  3.3.1. Crystal lattices and unit cells  3.3.2. Defects in solids  3.3.3. Electrical and magnetic properties  3.3.4. Superconductivity  3.4. Bio-inorganic chemistry  3.4.1. Metal ions in biology  3.4.2. Enzymatic reactions with metals  3.4.3. Metal poisoning and detoxification  3.4.4. Metalloproteins and Metalloenzymes
  4. Physical chemistry  4.1. Quantum Chemistry  4.1.1. Wave–particle duality  4.1.2. Schrödinger Equation  4.1.3. Quantum Numbers and Orbitals  4.1.4. Atomic and molecular spectroscopy  4.2. Statistical mechanics  4.2.1. Maxwell–Boltzmann distribution  4.2.2. Partitioning functions  4.2.3. Bose–Einstein and Fermi–Dirac statistics  4.3. Chemical thermodynamics  4.3.1. Gibbs Free Energy  4.3.2. Phase transition  4.3.3. Thermodynamic efficiency  4.4. Surface chemistry  4.4.1. Absorption and Catalysis  4.4.2. Colloids and Emulsions
  5. Analytical Chemistry  5.1. Classical methods  5.1.1. Gravimetric Analysis  5.1.2. titrimeter  5.2. Instrumental methods  5.2.1. Chromatography  5.2.2. Spectroscopy  5.2.3. Electroanalytical methods  5.2.4. X-ray diffraction
  6. Industrial Chemistry  6.1. Petrochemistry  6.2. Chemical engineering principles  6.3. Green Chemistry  6.4. Pharmaceuticals and Drug Synthesis
  7. Biochemistry  7.1. Carbohydrates  7.2. Proteins and enzymes  7.3. Lipids and membranes  7.4. Nucleic acids  7.5. Metabolism and Bioenergetics  7.6. Enzyme kinetics and mechanism

Undergraduate → Organic chemistry ↓


Hydrocarbons


Hydrocarbons are the backbone of organic chemistry and one of its most important components. They are organic compounds that consist exclusively of hydrogen and carbon atoms. Understanding hydrocarbons is important for understanding the structure and function of various organic molecules.

Types of hydrocarbons

Hydrocarbons can be classified into several categories. The two main groups are aliphatic hydrocarbons and aromatic hydrocarbons.

Aliphatic hydrocarbons

These hydrocarbons consist of straight chains, branched chains or non-aromatic rings. These are further divided into:

  • Alkanes: These are saturated hydrocarbons. They contain only single bonds between carbon atoms. A simple example is methane (CH4).
  • Alkenes: These are unsaturated hydrocarbons that contain at least one double bond. An example is ethene (C2H4).
  • Alkynes: These are unsaturated hydrocarbons that contain at least one triple bond. An example is ethyne (C2H2).
  • Cycloalkanes: These are saturated hydrocarbons that form ring structures. An example of this is cyclohexane (C6H12).

Aromatic hydrocarbons

Aromatic hydrocarbons or arenes contain conjugated ring systems with delocalized electrons according to Hückel's rule. A classic example of this is benzene (C6H6).

Alkenes: Structure and nomenclature

Alkanes are the simplest type of hydrocarbons. These are called saturated hydrocarbons because they contain only single covalent bonds. Let's take a look at their nomenclature and structural representation.

Naming of alkanes

The naming of alkenes follows a standard sequence:

  1. Identify the longest carbon chain as the parent hydrocarbon.
  2. Number the chain starting from the end nearest any substituent.
  3. Give the name and number of substituents.
  4. Collect the names, and list the replacement words alphabetically.

For example, consider the following compound:

CH3-CH2-CH(CH3)-CH3

- Longest chain: Propane (3 carbons)
- Substituent: methyl group on the second carbon
- Name: 2-Methylpropane

Alkene: Structure and representation

Alkenes are unsaturated hydrocarbons that contain at least one double bond. This double bond gives rise to the possibility of cis-trans isomerism.

Double bond and isomerism

The double bond is important to the chemical properties of the alkene. It is represented as:

C=C /  HH

Isomers such as cis and trans are related by the spatial arrangement around the double bond:

  • Cis-isomer: Two identical groups are on the same side of the double bond.
  • Trans-isomers: identical groups are in opposite directions.

Nomenclature of alkenes

The naming of alkenes follows the same pattern as the naming of alkenes:

  1. Determine the longest chain containing a double bond.
  2. Number the chain in such a way that the number of double bonds is minimum.
  3. State the position of the double bond in the name.

For example, for CH3-CH=CH-CH3, the structure name is but-2-ene.

Alkynes: Structure and characteristics

Alkynes are unsaturated hydrocarbons that contain at least one triple bond. This triple bond gives them linear geometry.

Triple bond representation

The triple bond is usually drawn as follows:

C≡C

Naming of alkynes

  1. Identify the longest chain that contains a triple bond.
  2. Number the chain in such a way that the triple bond is numbered the least.
  3. The position of the triple bond must be mentioned in the name.

For example, HC≡CH is ethyne, and CH3-C≡CH is propyne.

Cycloalkanes: Ring structures

Cycloalkanes are saturated hydrocarbons arranged in a ring. They have two fewer hydrogen atoms than their open-chain alkane counterparts. There is a slight deviation in their nomenclature:

Naming of cycloalkanes

  • Preceding the name of the alkane with "cyclo" followed by the name indicating the number of carbons in the ring.

Examples include:

  • Cyclopropane: A three-carbon ring.
  • Cyclobutane: A four carbon ring.
  • Cyclohexane: A six-carbon ring.

Aromatic hydrocarbons: Benzene and beyond

Aromatic hydrocarbons like benzene have special stability due to electron delocalization. They obey Huckel's rule for aromaticity.

Benzene structure and stability

Benzene (C6H6 is often depicted with single and double bonds, but an accurate representation includes a circle inside a hexagon indicating dislocations.

Aromaticity and Hückel's rule

Hückel's rule states that for a molecule to be aromatic, it must have (4n + 2) π electrons (where n is an integer) in a cyclic conjugated system.

Other aromatic hydrocarbons include:

  • Naphthalene: Made up of two fused benzene rings.
  • Anthracene: Consists of three linearly fused benzene rings.

Physical properties of hydrocarbons

The physical properties of hydrocarbons are affected by their molecular structure. These include boiling point, melting point, solubility, and density.

Boiling and melting point

Boiling and melting points generally increase with molecular weight. More branched alkanes have lower boiling points than their straight-chain isomers.

Solubility

Hydrocarbons are nonpolar and therefore insoluble in water. They are soluble in organic solvents such as benzene and ether.

Density

Hydrocarbons are less dense than water. Therefore, oil (a mixture of hydrocarbons) floats on water.

Reactions of hydrocarbons

Hydrocarbons undergo a variety of reactions. These reactions are the basis of many organic synthesis processes.

Combustion

Alkanes, alkenes, and alkynes react with oxygen in combustion reactions. For example, the complete combustion of methane:

CH4 + 2O2 → CO2 + 2H2O

Addition reactions

Addition reactions are typical for unsaturated hydrocarbons. Alkenes and alkynes can add hydrogen, halogens, and other groups. For example, the reaction of ethene with bromine:

C2H4 + Br2 → C2H4Br2

Substitution reactions

Alkenes undergo substitution reactions, particularly halogenation. In these reactions, a hydrogen atom is replaced by a halogen atom.

Aromatic substitution

Aromatic hydrocarbons undergo electrophilic aromatic substitution reactions. Typical examples include the nitration and sulfonation of benzene:

C6H6 + HNO3 → C6H5NO2 + H2O

Conclusion

Hydrocarbons are fundamental organic molecules that form the basis of organic chemistry. Understanding their structure, types, and properties is important for understanding more complex chemical concepts. From simple alkanes to complex aromatic structures, hydrocarbons represent both diversity and uncompromising simplicity at the core of organic matter.

The exploration of hydrocarbons provides us with tools for synthesizing new substances and understanding natural processes, making chemistry a continually evolving subject.


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Hydrocarbons

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