A Level Organic Chemistry Review

A comprehensive set of 50 flashcards covering organic chemistry concepts, reactions, and mechanisms based on the provided lecture notes.

What is the definition of organic chemistry according to the lecture notes?

Organic chemistry is the study of carbon-containing compounds.

What specific ability of carbon allows for the enormous diversity of organic molecules?

Carbon can form strong covalent bonds with itself and other atoms ($H$, $O$, $N$, $S$, Halogens) and create multiple bonds, resulting in complex chains and rings.

Define a 'Homologous series' in organic chemistry.

A group or family of organic compounds with the same functional group, the same general formula, and similar chemical properties.

What is the general formula for Alkanes?

$$C_nH_{2n+2}$$

What is the general formula for Alkenes?

$$C_nH_{2n}$$

What is the general formula for Alcohols?

$$C_nH_{2n+1}OH$$

According to the lecture, what dictates the chemical reactivity of an organic compound family?

The functional group.

How do boiling points of organic compounds change with molecular size and branching?

Boiling point increases with increase in molecular size or mass and decreases with increased branching.

What IUPAC prefix is used for a parent carbon chain containing 5 carbon atoms?

Pent-

Which IUPAC suffix is used to denote the ketone organic family?

-one

Define 'Isomerism' as described in the module.

Isomerism is the existence of different compounds with the same molecular formula but different structural formulas or spatial arrangements.

What is the difference between 'Cis-' and 'Trans-' geometrical isomers?

In Cis-isomers, identical groups are on the same side of the double bond; in Trans-isomers, they are on opposite sides.

What is a 'chiral centre' in the context of optical isomerism?

A carbon atom that is bonded to four different groups.

What is a 'racemic mixture' or 'racemate'?

An equimolar mixture of $(+)$ and $(-)$ enantiomers that is optically inactive.

Define a 'Substitution reaction'.

A reaction occurring when an atom or group of atoms replaces another in an organic molecule.

What are 'Nucleophiles'?

Ions or molecules attracted to positively charged centres (nucleus seeking), often possessing a lone pair of electrons such as $OH^-$, $CN^-$, or $NH_3$.

What is 'Homolytic Fission'?

The cleavage of a covalent bond where both bonded atoms acquire one electron of the bond, forming free radicals.

What is the bond angle around each carbon atom in saturated alkanes to minimize repulsion?

$$104.5^{\circ}$$

What are the conditions for industrial thermal cracking of high molecular mass alkanes?

Heating at high temperatures (about $900^{\circ}C$) in the absence of air and a catalyst.

State the general equation for the combustion of an alkane in an excess supply of oxygen.

$$C_xH_y + (x + \frac{y}{4})O_2 \rightarrow xCO_2 + \frac{y}{2}H_2O$$

What are the two leaded petrol additives mentioned to ensure smooth combustion?

Lead tetraethyl $Pb(C_2H_5)_4$ and $1,2-\text{dibromoethane}$ ($BrCH_2CH_2Br$).

How does a catalytic converter remove $NO$ and $CO$ from car exhaust?

$NO(g)$ oxidizes $CO$ to $CO_2$ and is itself reduced to $N_2(g)$, following the equation: $NO(g) + 2CO(g) \rightarrow N_2(g) + 2CO_2(g)$.

What is required to initiate the halogenation (free radical substitution) of alkanes?

A flash of $UV$ light.

State 'Markovnikoff’s Rule'.

When a molecule $HA$ adds to an asymmetric alkene, the major product is the one in which the hydrogen atom attaches to the carbon atom already carrying the larger number of hydrogen atoms.

What specific catalyst and conditions are used for the hydration (addition of steam) of alkanes to produce alcohols?

A strong acid ($H_3PO_4$) or $SiO_2$ catalyst at $300^{\circ}C$ and $60\,\text{atm}$.

What organic product is formed when ethene reacts with cold, dilute, alkaline $KMnO_4$?

$\text{Ethan-1,2-diol}$ ($HOCH_2CH_2OH$).

During the strong oxidation of alkenes using hot, concentrated $KMnO_4$, what is produced if the double-bonded carbon is attached to two alkyl groups?

A ketone.

Define 'Addition Polymerisation'.

A process where monomers add to each other producing a single product, often occurring through the rupturing of $\pi$-bonds in alkenes.

What is the carbon-to-carbon bond length in benzene compared to cyclohexane?

In benzene it is $0.139\,\text{nm}$, while in cyclohexane it is $0.154\,\text{nm}$.

What reagents are used in the 'nitrating mixture' to produce nitrobenzene?

Concentrated $HNO_3$ and concentrated $H_2SO_4$.

Why is phenol more reactive toward electrophiles than benzene?

The lone pair of electrons on the oxygen is partially delocalised into the $\pi$-ring system, increasing the electron density.

Into what is the methyl group of methylbenzene oxidized when using hot acidified $KMnO_4$?

A carboxylic acid ($C_6H_5COOH$).

Rank the reactivity of halogenoalkanes based on the halogen attached.

Iodo > bromo > chloro compounds.

What distinguishes an $S_N1$ mechanism from an $S_N2$ mechanism?

$S_N1$ is a first-order reaction where the rate depends only on the [halogenoalkane]; $S_N2$ is a second-order reaction where the rate depends on both the [nucleophile] and the [halogenoalkane].

What precipitate is formed when an iodo-compound is boiled with $NaOH$ and then reacted with $AgNO_3$?

A yellow precipitate of $AgI$.

Explain the role of $Cl^\bullet$ radicals in ozone depletion.

$UV$ radiation breaks $CFC$s to release $Cl^\bullet$ radicals, which react with ozone ($O_3$) to form $ClO^\bullet$ and $O_2$, inhibiting the natural ozone cycle.

Compare the relative acidities of phenol, water, and ethanol.

Phenol > water > ethanol.

What reaction is used to test for the presence of the $-OH$ group in alcohols by evolving white fumes?

The reaction with Phosphorus pentachloride ($PCl_5$), which produces $HCl$ (white fumes).

Which alcohols give a positive result in the triiodomethane (iodoform) reaction?

Alcohols containing the $CH_3CH(OH)-$ group, such as ethanol and all secondary alcohols with a terminal methyl group.

How can Tollen’s reagent distinguish an aldehyde from a ketone?

Aldehydes reduce the complex silver (I) ions in Tollen’s reagent to grey metallic silver (a silver mirror), while ketones do not react.

What reagent is used to reduce carboxylic acids to primary alcohols?

$LiAlH_4$ (in ethoxyethane).

What reagents are used to prepare acyl chlorides from carboxylic acids?

$PCl_5$ or $SOCl_2$.

What is the typical use of esters in the food and cosmetic industries?

They are used as food flavouring and in perfumes due to their characteristic sweet scents.

Rank the basicity of ethylamine, ammonia, and phenylamine.

Ethylamine > ammonia > phenylamine.

What are the required conditions for the formation of diazonium salts from phenylamine?

Reaction with nitrous acid ($HNO_2$) below $5^{\circ}C$.

What reagent causes the dehydration of amides to form nitriles?

Phosphorus ($V$) oxide ($P_2O_5$).

Define a 'zwitterion' in the context of amino acids.

A dipolar ion that results when the carboxylic group protonates the amine group within the same amino acid molecule.

Name four forces that hold the tertiary structure of a protein together.

1. Hydrogen bonds, 2. Permanent and induced dipole attractions, 3. Ionic attractions ($COO^-$ and $NH_3^+$), 4. Disulphide ($-S-S-$) bridges.

In electrophoresis, which way does a protein migrate if the solution pH is above its isoelectric point?

Toward the positive electrode (anode), because the protein has a net negative charge.

What are the specific monomers for the formation of Nylon 6.6?

Hexane-1,6-diamine ($H_2N(CH_2)_6NH_2$) and Hexane-1,6-dioic acid ($HO_2C(CH_2)_4CO_2H$).