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 ↓


Spectroscopy and structural analysis


Spectroscopy and structural analysis are fundamental techniques in organic chemistry that enable us to identify and understand the structure of organic molecules. The aim of this guide is to provide a detailed overview of these techniques, explaining their principles and applications in a simple way.

Introduction to spectroscopy

Spectroscopy is a method that uses the interaction between light and matter to analyze substances. By studying the radiation absorbed or emitted by substances, we can infer details about the molecular structure. This technique is non-destructive and can provide detailed information about compounds.

Types of spectroscopy

1. Infrared (IR) spectroscopy

IR spectroscopy measures the absorption of infrared light by molecules, which causes them to vibrate at specific frequencies. These vibrations are characteristic of different chemical bonds and can be used to interpret functional groups in organic compounds.

4000 cm -1 400 cm -1 C=O

IR spectrum showing a typical carbonyl (C=O) absorption near 1700 cm -1.

For example, a strong absorption band around 1700 cm -1 is indicative of a carbonyl group (C=O). A peak near 3300 cm -1 often suggests the presence of an OH group.

2. Nuclear magnetic resonance (NMR) spectroscopy

NMR spectroscopy is used to determine the structure of organic compounds by observing the magnetic properties of atomic nuclei. The most common type is proton NMR (1H NMR), which examines the hydrogen atoms in molecules.

        1H NMR (ppm):
        δ 9.0 - 10.0 : RCHO
        δ 6.5–8.0 : ArH
        δ 4.5 - 6.5 : Vinyl (RCH=CH2)
        δ 2.0 - 2.5 : CH3C(=O)R
        δ 0.5 - 1.5 : RCH3
1 5 9

NMR spectrum showing chemical shifts for different protons.

3. Ultraviolet-visible (UV-Vis) spectroscopy

UV-vis spectroscopy measures the absorption of ultraviolet or visible light by electrons in a molecule. This can reveal information about conjugated systems. Compounds with extensive π-electron systems can absorb at longer wavelengths, providing information about their structure.

Structural analysis techniques

1. Mass spectrometry (MS)

Mass spectrometry provides information about the molecular weight and structure of a molecule. In MS, a sample is ionized, and the ions are separated by their mass-to-charge ratio. The resulting mass spectrum reveals the relative abundance of different ions, allowing structural elucidation.

        Mass spectrum:
        m/z 46: CH3CH2OH
        m/z 31: CH2OH+
        m/z 29: CH3CH2+

2. Crystallography

X-ray crystallography is another powerful technique for determining the three-dimensional arrangement of atoms within a crystal. Although usually used for more complex structures, it provides precise atomic-level details.

Applications and examples

Now let's look at some real-world examples that show how these techniques are used in practice:

Example 1: Identifying an unknown compound

Imagine that you are given an unknown organic compound whose IR spectrum shows a strong absorption band at 1715 cm -1 and a strong singlet in δ 2.1 region of the 1H NMR spectrum. This pattern corresponds to acetone.

Example 2: Determining compound purity

NMR spectroscopy can also be used to check the purity of a substance. Any unexpected peaks may indicate impurities. For example, if you expect only aromatic protons in δ 7.0 - 8.0 ppm region and discover unexpected peaks, the sample may be contaminated.

Example 3: Monitoring response progress

Spectroscopy can monitor chemical reactions. During synthesis, you can take 1H NMR spectra periodically to observe changes in chemical shifts and associated peaks, which indicate the formation of products or the reduction of reactants.

Conclusion

Spectroscopy and structural analysis are integral to understanding organic chemistry. These methods allow chemists to quickly and accurately determine molecular structures, assess the purity of a sample, and gain insight into chemical dynamics and mechanisms.

With an understanding of these techniques, chemists can identify compounds, elucidate structures, and advance research and development in the chemical sciences. Further exploration and practice will increase your proficiency in these fundamental tools of organic chemistry.


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Spectroscopy and structural analysis

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