Organic Chemistry Notes

Organic Chemistry is the branch of chemistry studying the structure, properties, composition, reactions, and synthesis of organic compounds containing carbon atoms.
It focuses on compounds primarily made of carbon and hydrogen, but may also include oxygen, nitrogen, sulfur, and halogens.

Carbon forms stable bonds with itself and almost all elements (except noble gases).
Carbon can form stable different kinds of bonds with itself and with other elements.
Carbon can form stable long chains of bonds (polymeric structures).

Pauli Exclusion Principle: No two electrons in an atom can have the same values for all four quantum numbers.
Aufbau Principle: Electrons first occupy the lowest energy levels available.
Hund's Rule: When multiple orbitals of equal energy are available, each is singly occupied with parallel spins before double occupation occurs.

Main-group elements tend to bond in such a way that each atom has eight electrons in its valence shell, resembling a noble gas configuration.
Carbon has 4 valence electrons and needs 4 more to achieve an octet.
Carbon makes 4 chemical bonds to be stable.

Atoms form bonds to achieve a stable noble-gas conformation (octet rule).
Two main types of chemical bonds: ionic and covalent.
Bond formation depends on the electronegativity of the atoms involved.
Electronegativity indicates how strongly an atom attracts electrons in a molecule.
Bohr Atomic Model: Atoms consist of a positively charged nucleus (protons and neutrons) and negatively charged electrons moving on circular paths (energy levels, shells).

Occurs when there's a large difference in electronegativity between two atoms.
Involves electron transfer from one atom to another.
Ionic bonding is the electrostatic attraction between oppositely charged ions (cation and anion).

One or more electron pairs are shared between two atoms.
Covalent bonds can be non-polar or polar.
Non-polar Covalent Bonds: Formed between two identical atoms; electron pairs are shared equally, resulting in even electron density.
Electrons are not transferred completely, but they are put in common when there is no difference in electronegativity between atoms (or the difference is small).
Polar Covalent Bonds: Formed between two different atoms; electron pairs are not shared evenly.
Electrons are more attracted to the atom with higher electronegativity.
Almost all bonds in organic compounds are covalent.
Very similar electronegativity (EN): non-polar bond.
Different EN: polar bond.
δ+ and δ− notation indicates partial positive and negative charges due to unequal sharing.
Electronegativity trends: C < N < O < F, P < N, S < O, Cl < F

Atomic orbitals of the outer shell can undergo hybridization (linear combination of wave-functions of AOs).
Covalent bond forms through the overlap of two atomic orbitals (AO).
Hybrid orbitals facilitate electron pairing for chemical bond formation.
Hybridizing all outer shell orbitals of C yields four sp^3 hybrid orbitals.
sp^3 hybrid orbital: \frac{3}{4} 2p + \frac{1}{4} 2s

Double bonds are formed with sp^2 hybridized atomic orbitals and a p-orbital.
Single bonds are formed with sp^3 hybridized atomic orbitals (unless only s is available).
Triple bonds are formed with sp hybridized atomic orbitals and a p-orbital.
Each covalent bond (\textbf{—}) represents two electrons in common.
A double bond represents the sharing of two pairs of electrons.
A triple bond represents the sharing of three pairs of electrons

\sigma bonds: Formed by the direct overlap of atomic orbitals.
\pi bonds: Formed by the sideways overlap of p orbitals.
Phase agreement is required for orbital overlap; discordance results in non-bonding molecular orbitals.

A covalent bond represents two electrons (one electron pair) and is represented by a line.

Constitutional formula (structural formula): Depicts how atoms and groups are connected.
Condensed structural formula: Written in a single line.
Skeletal formula (line-angle formula): Shorthand representation, omitting C and H (when bonded to C).

Stereochemical formula indicates the spatial arrangement of atoms and groups in a molecule:
- "Normal" link: Lies in the writing plane.
- "Wedge" link: Projects out of the writing plane towards the observer.
- "Dashed" link: Projects out of the writing plane away from the observer.

Skeletal representation is the most convenient and fast way to represent an organic molecule.

Aspirin was Bayer's brand name: a blend of the prefix a(cetyl) + spir (from Spiraea, the meadowsweet plant genus from which acetylsalicylic acid was originally derived at Bayer) + -in (the common chemical suffix).
A nonsteroidal anti-inflammatory drug (NSAID) used to reduce pain, fever, and inflammation, and as an antithrombotic.
Common adverse effect: upset stomach. Significant side effects: stomach ulcers, stomach bleeding, and worsening asthma.