Amines Lecture Notes

Flashcards covering nomenclature, physical properties, basicity, synthesis methods, and chemical reactions of amines and diazonium salts.

Amines

Organic compounds that are derivatives of ammonia ($NH_3$) and act as bases in biochemical acid-base reactions.

Primary amine

An amine classified by having one alkyl or aryl group substituted on the nitrogen atom.

Aniline

The parent name for amino derivatives of benzene ($C_6H_5NH_2$).

Quaternary amines

Amines named as ammonium ions where the nitrogen is substituted with four organic groups and carries a positive charge.

Basicity and $pK_a$ relationship

The more basic the amine, the larger the $pK_a$ of its conjugate acid; conversely, the more basic the amine, the weaker its conjugate acid.

Arylamines basicity

Nitrogen compounds that are approximately 1 million times ($6$ $pK_a$ units) weaker bases than ammonia and alkylamines.

Gabriel Synthesis

A clean method for preparing primary amines that involves the formation and alkylation of N-Potassiophthalimide followed by the release of the amine.

Reductive Amination

A single reaction combining the formation of an imine from a ketone/aldehyde with the reduction of that imine to an amine, often using $NaBH_3CN$.

Hofmann Elimination

An elimination reaction of a quaternary ammonium hydroxide that undergoes E2 $\beta$-elimination to form the least substituted alkene.

Nitrosamines

Carcinogenic compounds formed by the reaction of nitrosyl cations with secondary amines; examples include N-Nitrosodimethylamine found in tobacco smoke and fried bacon.

Schiemann reaction

The formation of aryl fluorides by heating the tetrafluoroborate ($HBF_4$) salts of diazonium cations.

Sandmeyer reactions

Reactions that use copper(I) salts (such as $CuCl$, $CuBr$, or $CuCN$) to replace the nitrogen in aryl diazonium salts with other substituents.

Azo Coupling

A reaction where aryl diazonium cations, acting as weak electrophiles, attack activated aromatic rings to form diazo compounds like Methyl red.

Infrared (IR) Spectroscopy of Amines

Primary alkyl- and arylamines exhibit two peaks in the $3000-3500\text{ cm}^{-1}$ range, while secondary amines exhibit only one peak.

Nitrogen Rule (Mass Spectrometry)

A guideline stating that compounds with an odd number of nitrogen atoms have an odd molecular weight, while an even number of nitrogens results in an even molecular weight.