Organic Chemistry Fundamentals and Spectroscopy

Flashcards covering organic chemistry principles including acidity/basicity, resonance, spectroscopy (IR, NMR), stereochemistry, and reaction mechanisms (SN1, SN2, E1, E2, addition).

Acidity of Ethanol vs. Ethylamine

Ethanol ($CH_3CH_2OH$) is a stronger acid than ethylamine ($CH_3CH_2NH_2$) because oxygen is more electronegative than nitrogen and better stabilizes the negative charge in the conjugate base.

Basicity of Acetate vs. Trifluoroacetate

Acetate ($CH_3COO^-$) is a stronger base than trifluoroacetate ($CF_3COO^-$) because trifluoroacetate is stabilized by induction from the fluorine atoms, making it a weaker base.

Acetonitrile Nitrogen Hybridization

The nitrogen atom in acetonitrile is $sp$ hybridized, and its lone pair occupies an $sp$ orbital.

Nucleophilicity: Carbon vs. Oxygen

Carbon is less electronegative and more nucleophilic than oxygen, leading to faster reaction rates when acting as a nucleophile.

Basicity and Orbital Energy

A molecule is a weaker base if its lone pair is in a lower energy orbital, making the molecule less reactive.

IR Spectroscopy

An analytical technique most useful for identifying the types of functional groups present in a molecule.

13C NMR Spectroscopy

A technique used to identify the number of unique types of carbons in a molecule.

1H NMR Spectroscopy

A technique used to identify the number of unique types of hydrogens in a molecule, often showing splitting patterns like doublets, singlets, or septets.

Deshielding in NMR

An effect where a carbon or hydrogen is partially positive due to nearby electronegative atoms, causing its signal to shift to a higher chemical shift (ppm).

IR Stretching Frequency

Measured in wavenumbers ($cm^{-1}$); a higher stretching frequency indicates that a bond requires more energy to stretch.

Oxidation of Benzyl Alcohol to Benaldehyde

A reaction where the $O-H$ IR signal disappears and a $C=O$ stretch appears, and the ring protons in the product shift to higher chemical shifts (deshielded) because the ring carbons become more positive.

Cis-1,4-dimethylcyclohexane Stability

The most stable chair conformation for this molecule has one methyl group in an axial position and one methyl group in an equatorial position.

Cyclohexane Chair Flip

A conformational change where an equatorial hydrogen pointing up becomes an axial hydrogen pointing up.

Enantiomers

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

Torsional and Angle Strain

Factors that increase the energy of a cyclic compound, making it react faster in ring-opening reactions.

Staggered Conformation

A low-energy conformation visualized in Newman projections that minimizes electron-electron repulsion.

SN2 Reaction Factors

Reaction rate depends on the concentration of the electrophile, the concentration of the nucleophile, and the value of the rate constant.

SN2 Stereochemistry

Characterized by the inversion of the stereochemistry at the alpha carbon.

Polar Aprotic Solvents

Solvents that accelerate $S_N2$ reactions because they do not solvate the nucleophile, making it more reactive.

Carbocation Stabilization

Stabilization occurring through hyperconjugation (electron donation from adjacent bonds) and resonance.

E2 Reaction Requirement

Requires the removal of an anticoplanar $\beta$-hydrogen to form an alkene.

Exergonic Reaction

A reaction that releases energy, often depicted in energy diagrams where the products are lower in energy than the reactants.

Cyclic Bromonium Ion

An intermediate formed during the reaction of an alkene with bromine ($Br_2$), which leads to trans-addition products via $S_N2$ attack.

Enol Intermediate

An intermediate formed during the acid-catalyzed addition of water to an alkyne.