Chemistry Class XII Vocabulary Review

A single parseable JSON array containing vocabulary terms and definitions from the Class XII NCERT Chemistry Part II textbook, covering organic reactions, biomolecules, polymers, and medicinal chemistry with mandatory LaTeX formatting for all mathematical and chemical expressions.

Haloalkanes

Organic compounds formed by the replacement of hydrogen atom(s) in an aliphatic hydrocarbon by halogen atom(s), where the halogen is attached to an $sp^3$ hybridised carbon atom.

Haloarenes

Organic compounds formed by the replacement of hydrogen atom(s) in an aromatic hydrocarbon by halogen atom(s), where the halogen is attached to an $sp^2$ hybridised carbon atom.

Geminal halides

Dihaloalkanes in which two halogen atoms are present on the same carbon atom, also known as alkylidene halides.

Vicinal halides

Dihaloalkanes in which two halogen atoms are present on adjacent carbon atoms, also known as alkylene dihalides.

Finkelstein reaction

A halogen exchange reaction where alkyl chlorides or bromides react with $NaI$ in dry acetone to produce alkyl iodides.

Swarts reaction

The synthesis of alkyl fluorides by heating an alkyl chloride or bromide in the presence of a metallic fluoride such as $AgF$, $Hg_2F_2$, or $CoF_2$.

SN1 Mechanism

A substitution nucleophilic unimolecular reaction that proceeds in two steps, depends on the concentration of only one reactant, and involves the formation of a carbocation intermediate.

SN2 Mechanism

A substitution nucleophilic bimolecular reaction that occurs in a single step with the simultaneous breaking of the old bond and formation of the new bond, leading to the inversion of configuration.

Zaitsev Rule

A rule stating that in dehydrohalogenation reactions, the preferred product is the alkene which has the greater number of alkyl groups attached to the doubly bonded carbon atoms.

Grignard Reagent

An organometallic compound with the general formula $RMgX$, obtained by the reaction of haloalkanes with magnesium metal in dry ether.

Wurtz Reaction

A reaction where alkyl halides react with sodium in dry ether to produce hydrocarbons containing double the number of carbon atoms present in the original halide.

Hydroboration-oxidation

A process where alkenes react with diborane to give trialkyl boranes, which are then oxidised by hydrogen peroxide in the presence of aqueous sodium hydroxide to yield alcohols.

Reimer-Tiemann reaction

A reaction where phenol is treated with chloroform in the presence of sodium hydroxide to introduce a $-CHO$ group at the ortho position, producing salicylaldehyde.

Kolbe’s reaction

The reaction of phenoxide ion with carbon dioxide ($CO_2$) followed by acidification to produce ortho-hydroxybenzoic acid (salicylic acid).

Williamson synthesis

A laboratory method for preparing symmetrical and unsymmetrical ethers by reacting an alkyl halide with sodium alkoxide.

Rosenmund reduction

The hydrogenation of an acyl chloride over a catalyst of palladium on barium sulphate to produce an aldehyde.

Stephen reaction

The reduction of nitriles to imines with stannous chloride and hydrochloric acid, followed by hydrolysis to yield aldehydes.

Etard reaction

The oxidation of the methyl group of toluene to a chromium complex using chromyl chloride ($CrO_2Cl_2$), which on hydrolysis yields benzaldehyde.

Gatterman-Koch reaction

The synthesis of benzaldehyde by treating benzene with carbon monoxide ($CO$) and hydrogen chloride ($HCl$) in the presence of anhydrous aluminium chloride.

Aldol condensation

A reaction involving aldehydes or ketones with at least one $\alpha\text{-hydrogen}$ in the presence of dilute alkali to form $\beta\text{-hydroxy}$ aldehydes or ketones, which then undergo dehydration.

Cannizzaro reaction

A disproportionation reaction of aldehydes that do not have an $\alpha\text{-hydrogen}$ when treated with concentrated alkali, resulting in one molecule of alcohol and one molecule of carboxylic acid salt.

Hell-Volhard-Zelinsky reaction

The halogenation of carboxylic acids at the $\alpha\text{-position}$ using chlorine or bromine in the presence of red phosphorus.

Gabriel phthalimide synthesis

A method used for the preparation of primary amines by reacting phthalimide with ethanolic potassium hydroxide and an alkyl halide, followed by alkaline hydrolysis.

Hoffmann bromamide degradation

A reaction used to prepare primary amines with one less carbon atom by treating an amide with bromine in an aqueous or ethanolic solution of sodium hydroxide.

Zwitter ion

A dipolar ion formed in amino acids when the carboxyl group loses a proton and the amino group accepts a proton, resulting in a neutral species with both positive and negative charges.

Peptide linkage

An amide bond ($\text{-CO-NH-}$) formed between the carboxyl group of one amino acid and the amino group of another with the elimination of a water molecule.

Denaturation of proteins

The process where a protein loses its biological activity due to physical or chemical changes (like temperature or pH) that disrupt its secondary and tertiary structures.

Glycosidic linkage

An oxide linkage between two monosaccharide units formed through the loss of a water molecule.

Nucleoside

A unit formed by the attachment of a nitrogenous base to the $1'$ position of a pentose sugar.

Nucleotide

A unit formed when a nucleoside is linked to phosphoric acid at the $5'$ position of the sugar moiety.

Homopolymer

An addition polymer formed by the polymerisation of a single monomeric species, such as polythene.

Copolymer

A polymer made by addition polymerisation from two or more different monomeric species, such as Buna-S.

Vulcanisation

The process of heating natural rubber with sulphur ($S$) to form cross-links, improving the physical properties of the rubber.

PHBV

Poly $\beta\text{-hydroxybutyrate - co - } \beta\text{ -hydroxy valerate}$, a biodegradable polyester used in speciality packaging and orthopaedic devices.

Chemotherapy

The use of chemicals for therapeutic effects in the treatment, prevention, or diagnosis of diseases.

Antacids

Chemical substances that neutralise excess acid in the stomach and raise the pH to an appropriate level.

Antihistamines

Drugs that interfere with the natural action of histamine by competing for binding sites on receptors, used to treat allergies.

Tranquilizers

A class of chemical compounds used for the treatment of stress and mild or severe mental diseases by inducing a sense of well-being.

Antipyretics

Drugs used to reduce body temperature during fever, such as aspirin or paracetamol.

Saponification

The alkaline hydrolysis of glyceryl esters of fatty acids (fats) to produce soap and glycerol.