Organic Chemistry Chapter 14A

The second semester covers similar topics and exams as the first semester.
- Each exam has approximately 125 points.
- Except for the final exam which consists of two parts:
- Part 1 focuses on biochemistry content, taught in the last three weeks of the semester.
- Part 2 is a post-test.
Many functional groups from organic chemistry relate directly to biochemical applications, important for students interested in healthcare.
- Example given: "peptide linkage" in biochemistry refers to an "amide" in organic chemistry.
The course will transition from organic chemistry to applied biochemical functions, highlighting relevant topics.

Five exams are scheduled:
- The last exam is in two parts: biochemistry content and the post-test.
- The post-test is easier than previous tests, and students often perform better on it based on experience.
Grading scale:
- Standard grading is maintained with 85% as an A grade, 90% in the lab.
- Grace and mercy policies will be in effect for borderline students.

Topics covered in second semester:
- Spectroscopy (Chapter 14) - methods of using electromagnetic radiation to study chemical structure.
- Organometallics (Chapter 15) - interface of inorganic and organic chemistry, emphasizing its relevance to health sciences.
- Chapters on organic functional groups resume in Chapter 16, including: ethers, alcohols, carbonyl compounds, amines, and their relevance to biochemical pathways.
- The foundation laid in the first semester is vital for understanding advanced topics in this semester.

Definition of spectroscopy:
- "Spectroscopy" involves the use of electromagnetic radiation to study chemical structure.
- Terms explained:
- "Spectro" - refers to light and spectrum.
- "Scope" - refers to measurement.
Almost every type of electromagnetic radiation can be utilized to determine chemical behavior and structure.

NMR, often confused with MRI, uses the same underlying technology but is simpler in chemical applications compared to MRI.
- Popular due to its radio frequency application, thereby ensuring safety and convenience in usage.
Foundational to understanding many areas in organic chemistry due to its ability to reveal molecular structures based on nuclear behavior.

Infrared spectroscopy is another useful method to differentiate between organic functional groups.
- Infrared radiation has enough energy to perturb molecular bonds, allowing measurement of bond interactions.
- Useful in determining material-specific information in organic chemistry.

The course will not cover techniques such as UV-Vis, X-ray spectroscopy, or gamma radiation due to their complexity or lower relevance in the immediate organic chemistry context.

The electromagnetic spectrum includes various energy types from radio waves (low energy) to gamma rays (high energy).
Radio waves are beneficial for NMR as they are safe and non-damaging to living tissues.
High-energy effects like X-ray are significant in analytical chemistry but are handled with caution due to potential damage.

Important historical context: NMR was discovered in 1952 by physicists Gibby, Pines, and Wall.
Key terms introduced:
- Chemical shift - a way to measure functional group changes due to radio wave absorption.
- Isotopes: Hydrogen-1 (99% of hydrogen) is sensitive to NMR, while Deuterium (Hydrogen-2) is not.
In NMR, molecules exhibit different behavior under magnetic fields, aligning similarly to compasses, allowing measurement of hydrogen and organic structure.
The larger the magnet, the better the spectroscopy response due to efficient alignment of atoms in a magnetic field.

NMR measures the response of nuclei in a magnetic field, exhibiting different resonance frequencies based on their electronic environment.
Electronic environments of protons influence chemical shifts according to their exposure to electronegative atoms.
- Shielded protons (lower chemical shift) reign around environments with low electronegativity.
- Deshielded protons (higher chemical shift) appear in environments of high electronegativity like oxygen or halogens.
Spectra produced display proton signals that correlate with molecular structures allowing students to deduce chemical environments.

Interpretation of NMR spectra requires knowledge of chemical environments:
- Each distinct environment of hydrogens in a molecule produces different signals, assisting determination of molecular structure.
- The area under each peak in an NMR spectrum quantifies the number of protons in the respective environment, aiding in deducing molecular formulae from integrations.
Example of using integration to demonstrate quantification of hydrogen environments in organic molecules (e.g., ethanol).
Integration reveals quantitative relationships between signals in a spectrum.

The proximity of different atoms creates complex signal patterns, known as spin-spin splitting which can yield n + 1 peaks, explaining peak multiplicity in spectra.
Adjacent groups influence each other’s resonance behavior leading to complex structures observable in spectra.
Key terms:
- "N+1 Rule" for determining the multiplicity of signals based on adjacent hydrogen atoms.

NMR is a powerful tool for structural determination in organic chemistry and biochemistry.
Each chapter in the semester builds on previously established concepts ensuring a cumulative understanding of organic chemistry’s relevance to biochemical applications.
Students encouraged to engage actively with materials and to reach out with questions focusing on both practical applications and underlying principles of spectroscopy.