Part 5

provides a reference peak. The signal for its H atoms is assigned a delta = 0.

Deshielded

Can show: • The number of different carbons with their relative chemical environments. • Their number of hydrogens (spin coupled NMR only)

Most useful for studying compounds containing double bonds, and/or hetero atoms with lone pairs. Can be applied quantitatively by using Beer’s law.

A = epsilon(b)(c) A = absorbance (measured by UV) (epsilon) = a constant for the substance at a given wavelenght. b = path length (usually equal to one) c = concentration

Differs in that it is not true spectroscopy. No absorption of electromagnetic radiation is involved. Does not allow for reuse of sample. Helps in distinguishing certain compounds.

Separates dissolved substances based on differential solubility in aqueous versus organic solvents (oil and water). hydrogen bonding: alcohols/acids –> aqueous dipole-dipole: less likely to move to aqueous van der Waals: compounds are least likely to move into aqueous layer.

Separates solids from liquids

Separates solids based on differential solubility; temperature is important here.

Separates solids based on their ability to sublime. Must raise the temp at a low enough pressure, or lower the pressure at a very cold temperature.

Separates large things (like cells, organelles, and macromolecules) based on mass and density.

Separates liquids based on boiling point, which in turn depends on intermolecular forces.

Uses a stationary phase and a mobile phase to separate compounds based on how tightly they adhere (generally due to polarity but sometimes size as well).

Used to separate biological macromolecules (such as proteins or nucleic acids) based on size and sometimes charge.

Boiling points of amines are between those of alkanes and alcohols. Are bases and readily accept protons to form ammonium ions. Function as weak acids.

Alkyl halides + ammonia (NH3) –> alkylammonium halide salts. Ammonia functions as a nucleophile and displaces the halide atom. When the salt is treated with a base, the alkylamine product is formed. A SN2 reaction: halides are good leaving groups and ammonia is a good nucleophile

Converts a primary alkyl halide to a primary amine. Also a SN2 reaction.

• SN2 reactions: ammonia reacting with alkyl halides or gabriel synthesis. • Reduction of: amides, aniline and its derivatives, nitriles, and imines. Amines can be destroyed (converted to alkenes) by exhaustive methylation.

Product: Nitro replaced with Amine. Useful for aromatic compounds, because nitration of aromatic rings is facile. Fe or Zn + HCl: common reducing agent.

Product: Primary amines