Organic Chemistry III: Arenes, Amines, and Organic Synthesis

Flashcards covering vocabulary and core concepts from organic chemistry lectures on arenes, nitrogen compounds, polymers, and laboratory techniques.

Aliphatic

Straight or branched chain organic substances.

Aromatic (Arene)

Organic substances that include one or more ring of six carbon atoms with delocalised bonding.

Benzene

The simplest arene with the molecular formula $C_6H_6$, consisting of a hexagonal ring of carbon atoms where each carbon is bonded to two others and one hydrogen by single covalent $\sigma$-bonds.

Delocalised p electrons

Six electrons in benzene that occupy p orbitals perpendicular to the plane of the ring, forming a ring structure above and below the carbon atoms rather than being attached to a particular atom.

Delocalisation energy

The increase in thermodynamic stability connected to delocalisation; in benzene, it is the difference between the theoretical enthalpy of hydrogenation ($-360\,kJ\,mol^{-1}$) and the actual value ($-208\,kJ\,mol^{-1}$), equaling $-152\,kJ\,mol^{-1}$.

Electrophilic substitution

The most common reaction type for benzene, involving the replacement of a hydrogen atom with an electrophile to avoid breaking the stable delocalised system.

Phenyl group

A benzene ring regarded as a substituent side group, represented by the formula $C_6H_5$-.

Carcinogen

A cancer-causing molecule, such as benzene.

Nitration of Benzene

A reaction using concentrated nitric acid and a concentrated sulfuric acid catalyst at $60^\circ C$ to substitute a nitro group ($NO_2^+$) onto the ring.

Friedel Crafts Alkylation

The substitution of an alkyl group into a benzene ring using a chloroalkane and an anhydrous aluminium chloride ($AlCl_3$) catalyst under reflux.

Friedel Crafts Acylation

The substitution of an acyl group into a benzene ring using an acyl chloride and a anhydrous $AlCl_3$ catalyst to produce a phenyl ketone.

Phenol

An organic compound where an $-OH$ group is directly attached to a benzene ring, causing the lone pair on oxygen to delocalise into the ring.

Sodium phenoxide

The soluble salt formed when phenol reacts with sodium metal or sodium hydroxide ($NaOH$).

Amide

A functional group named with the suffix -amide (e.g., ethanamide), formed by the reaction of carboxylic acids or acyl chlorides with ammonia or amines.

Zwitterion

A dipolar ion that forms the common state of amino acids, featuring both a positive charge (on the amine group) and a negative charge (on the carboxylate group).

Condensation Polymerisation

A process where two different monomers add together, typically releasing a small molecule like $H_2O$ or $HCl$ and forming linkages like polyesters or polyamides.

Terylene

A common polyester manufactured from ethane-1,2-diol and benzene-1,4-dicarboxylic acid.

Nylon 6,6

A common polyamide formed from hexanedioic acid and hexane-1,6-diamine, so named because each monomer contains six carbons.

Kevlar

A high-strength polyamide polymer often used in bulletproof vests and industrial applications.

Peptide link

The amide functional group ($-CONH-$) that links amino acids together in a protein chain.

Rf value

In chromatography, the ratio of the distance moved by a substance (like an amino acid) to the distance moved by the solvent.

Ninhydrin

A reagent sprayed onto chromatography paper that produces red to blue spots when heated with amino acids, making them visible.

Grignard Reagent

A highly reactive organometallic compound (e.g., $CH_3CH_2MgI$) formed by reacting a halogenoalkane with magnesium in dry ether, used to increase carbon chain length.

Reflux

A laboratory technique involving the continuous boiling and condensing of a reaction mixture to prevent the loss of volatile organic vapours during long heating periods.

Anti-bumping granules

Small stones added to a flask during distillation or reflux to prevent vigorous, uneven boiling by promoting the formation of small bubbles.

Recrystallisation

A purification technique for organic solids involving dissolving the impure compound in a minimum volume of hot solvent, filtering, cooling, and suctioning the resulting crystals.

Steam distillation

A technique where steam is passed into a mixture to distil off product vapour at a lower temperature, preventing the decomposition of high-boiling point substances.

Tollen's Reagent

An aqueous solution of the silver(I) complex ion $[Ag(NH_3)_2]^+$ used to distinguish aldehydes (which form a silver mirror) from ketones.

Fehling’s Solution

A blue solution containing $Cu^{2+}$ ions that forms a red precipitate of $Cu_2O$ when heated with an aldehyde.