OCR (A) Chemistry A-level: Module 6 - Organic Chemistry and Analysis

These flashcards cover key concepts and definitions from Organic Chemistry and Analysis, specifically focusing on benzene, phenol, carbonyl compounds, amino acids, and spectroscopy.

What is benzene?

Benzene is a colourless, sweet-smelling, flammable liquid found in crude oil and cigarette smoke, and is a known carcinogen.

What is the Kekule model of benzene?

The Kekule model describes benzene as a 6-membered ring of carbon atoms joined by alternate single and double bonds.

What evidence contradicts the Kekule model of benzene?

Lack of reactivity, equal lengths of C-C bonds, and hydrogenation enthalpies being less exothermic than predicted.

Describe the delocalised model of benzene.

Benzene is a planar, cyclic, hexagonal hydrocarbon with 6 carbons and 6 hydrogens, with delocalized π-electrons across the ring.

What happens during nitration of benzene?

When the temperature exceeds 50°C, further substitution may occur, producing dinitrobenzene.

Why do halogen carriers need to be present in benzene reactions?

Unlike alkenes, benzene has delocalized π-electrons, leading to insufficient electron density for electrophilic attacks without a halogen carrier.

What is phenol and its simplest form?

Phenol is an aromatic compound with a hydroxyl group bonded directly to the benzene ring; the simplest form is C6H5OH.

How is phenol produced?

Phenol can be produced through multi-stage processes involving benzene and various chemicals, yielding high percentages.

What makes phenol more acidic than alcohols?

Phenol's hydroxyl group can partially dissociate, producing a phenoxide ion; it reacts with strong bases but not weak ones.

How do amino acids generally relate to carboxylic acids?

Amino acids contain both acidic carboxylic acid and basic amine groups, having functionalities similar to both.

What is optical isomerism?

Optical isomerism occurs in molecules with a chiral center, where two non-superimposable mirror images can exist.

What is the purpose of NMR spectroscopy in organic chemistry?

NMR spectroscopy provides information about the number of and environments of carbon or proton atoms within a molecule.

What does spin-spin coupling in proton NMR indicate?

Spin-spin coupling causes the splitting of peaks in NMR spectra, providing information about adjacent protons influencing each other's environment.

Define chromatography.

Chromatography is a technique used to separate individual components from a mixture of substances based on their interaction with stationary and mobile phases.