Organic Chemistry Exam 2 (Chapters 5-6) Review

This flashcard set covers stereochemistry, thermodynamic principles, and reaction mechanism terminology from Chapters 5 and 6 of the Organic Chemistry curriculum.

Crestor® (rosuvastatin)

A medication used to reduce cholesterol that has 8 possible stereoisomers based on its molecular structure.

Singulair® (montelukast)

A medication used to manage asthma that contains a chiral center with an R absolute configuration.

Plavix® (clopidogrel)

A medication used to manage blood clots which features a chirality center assigned the S absolute configuration.

Plane of symmetry

A tool used to determine chirality; a molecule contains one if it can be divided into two halves that would look identical if reflected in a mirror.

Cahn-Ingold-Prelog system

A system used to rank substituents by priority based on atomic number, where priorities in a specific case were ranked as -SH > -F > -OH > -H.

Intermediate

A species on a reaction pathway that represents a local minimum on an energy diagram.

Heterolytic cleavage

A type of bond cleavage where both electrons from the bond are taken by one of the atoms, typically occurring in ionic reactions.

Specific rotation

A physical property of chiral molecules; examples include $-61$ for $(R)$-carvone and $-116$ for $(S)$-limonene.

Enantiomeric excess (% ee)

A measurement of the purity of a chiral sample; for a carvone sample with an observed rotation of $-40$ and a pure rotation of $-61$, the % ee is $66\%$.

Meso isomer

An achiral compound that contains chiral centers and a plane of symmetry, often illustrated in structures containing substituted tartaric acid derivatives.

Transition state

A high-energy point on a reaction coordinate diagram representing a maximum energy state as bonds are being formed and broken.

Hydride

A hydrogen atom with a negative charge and two electrons, symbolized as $H^-$.

Concerted endothermic reaction

A chemical reaction that occurs in a single step (one transition state) where the energy of the products is higher than the energy of the reactants.

Enantiomers

Stereoisomers that are non-superimposable mirror images of each other.

Diastereomers

Stereoisomers that are not mirror images of each other.

Constitutional isomers

Compounds that have the same molecular formula but different connectivity of atoms.

Nucleophile

A reactant that provides an electron pair to form a new bond; frequently identified as electron-rich sites such as lone pairs or pi bonds.

Electrophile

An electron-deficient atom or molecule that accepts an electron pair from a nucleophile to form a new bond.

$\Delta S$ (Entropy)

A thermodynamic property representing disorder; it is predicted to be positive when a reaction results in an increase in the number of molecules.

Gibbs Free Energy Favorability

A reaction with $\Delta H = 20\,kJ/mol$ and $\Delta S = 10\,J/mol \cdot K$ at $298\,K$ will favor reactants.

Fischer projection

A 2D representation of a 3D molecule where horizontal lines represent bonds coming out of the page (wedges) and vertical lines represent bonds going into the page (dashes).