Lecture 28: Amines

A set of flashcards covering vocabulary and concepts related to amines, including their classifications, physical properties, basicity, synthesis, and industrial applications.

Amines

Derivatives of ammonia in which one or more of the hydrogen atoms in the ammonia molecule have been replaced by alkyl or aryl groups.

Primary amine ($1^{\circ}$)

An amine where one hydrogen atom in the ammonia molecule has been replaced by one substituent (R-group) on the nitrogen atom, with the general formula $RNH_2$.

Secondary amine ($2^{\circ}$)

An amine where two hydrogen atoms in the ammonia molecule have been replaced by two substituents (R-groups) on the nitrogen atom, with the general formula $RR'NH$.

Tertiary amine ($3^{\circ}$)

An amine where three hydrogen atoms in the ammonia molecule have been replaced by three substituents (R-groups) on the nitrogen atom, with the general formula $RR'R''N$.

Phenylamine

A specific arylamine ($C_6H_5NH_2$) that is almost the same density as water, relatively insoluble in it, and used as a starting point for making dyestuffs.

Amine bond angle

Approximately $107^{\circ}$, which is less than the perfect tetrahedral angle of $109.5^{\circ}$ due to the lone pair repelling the bonding pairs of electrons.

Inductive effect

The process by which alkyl groups release electrons towards the nitrogen atom, increasing the electron density and making the amine a better electron pair donor.

Brønsted-Lowry base

A proton ($H^+$) acceptor; amines act as this because they have a lone pair of electrons that can attract and bond with a proton.

Lewis base

A lone-pair donor; amines act as this when they donate their lone pair of electrons to a proton or electron-deficient carbon atom.

Nucleophile

A chemical species that uses a lone pair of electrons to form a bond with an electron-deficient carbon atom.

Quaternary ammonium salt

A compound with the formula $[R_4N]^+ X^-$ produced when a tertiary amine reacts further with a halogenoalkane.

Cationic surfactants

Quaternary ammonium compounds with long hydrocarbon chains and a positively charged organic group, used in hair and fabric conditioners to prevent static electricity build-up.

Reduction of nitriles

A two-step industrial process to prepare pure primary amines by reacting halogenoalkanes with cyanide ions to form nitriles, which are then reduced using a nickel/hydrogen ($Ni/H_2$) catalyst.

Synthesis of Phenylamine

A two-step process where benzene is first nitrated to nitrobenzene using concentrated $HNO_3$ and $H_2SO_4$, and then reduced using tin ($Sn$) and hydrochloric acid ($HCl$).

Pseudoephedrine

An amine-based drug used as a nasal decongestant (active ingredient in Sudafed), often supplied as a hydrochloride to increase solubility in the bloodstream.

Sulfanilamides

A class of anti-bacterial drugs, such as Prontosil Rubrum, that are converted in the body to sulfanilamide to prevent bacteria from synthesizing DNA by mimicking para-aminobenzoic acid (PABA).

N-substituted amides

The products formed when amines react with acid chlorides or acid anhydrides through nucleophilic substitution (addition-elimination) reactions.