Organic chemistry

Are carboxylic acids soluble in water and why

Yes they’re soluble in water because they can form hydrogen bonds with water

How does the solubility of carboxylic acids change as the alkyl chain increases

Solubility decreases

What reagents and conditions are needed to form a carboxylic acid from a primary alcohol

Heat under reflux with acidified potassium dichromate (VI)

Whats the test for a carboxylic acid

Fizzing with sodium carbonate/ turns limewater milky

Whats the product of a carboxylic acid reacting with metals

Salt + hydrogen

What are the products of carboxylic acids reacting with alkalis

Salt + water

What are the products of carboxylic acids reacting with carbonates

Salt + CO2 + water

What reagents and conditions are needed for carboxylic acids to form esters

Alcohol + concentrated acid catalyst + heat

What are the reagents are conditions for forming a carboxylic acid from an ester

Hot dilute aqueous acid + heat

What are the reagents and conditions for forming acrylic chlorides from carboxylic acids

Sulphur dichloride oxide

What reagents and conditions are needed to form a carboxylic acid from an acrylic chloride

Water

What reagents and conditions are needed to form esters from acyl chlorides

Alcohol

What reagents and conditions are needed to form phenylesters from acyl chlorides

Phenol

What reagents and conditions are needed to form amides from acyl chlorides

Ammonia

What reagents and conditions are needed to form secondary amides from acyl chlorides

Amines

Why are acyl chlorides more susceptible to nucleophilic attack

Because they have an electronegative oxygen atom attached to the delta positive carbon increasing the partial positive charge of the carbon making it even more reactive towards nucleophiles

Why are chlorobenzenes unreactive towards nucleophiles

The p-pi overlap between the lone pair on the chlorine atom and delocalised pi electrons in the ring strengthen the C-Cl bond making it harder to break, additionally the high electron density in the ring repels nucleophiles

How are acid anhydrides formed

The elimination of water from two of the same carboxylic acids

How can amines act as bases

The lone pair on the nitrogen atom can form a dative covalent bond to H+ allowing amine to act as a proton acceptor

What is the product of an amine reacting with an acid

A salt

How can amines be liberated from their salts

By reacting them with a stronger base (e.g. NaOH)

How are primary amines formed from haloalkanes

The nucleophilic substitution of haloalkanes heated with excess ammonia in ethanol

How are secondary and tertiary amines formed from haloalkanes

The nucleophilic substitution of haloalkanes heated with excess amines in ethanol

How are amines formed from nitriles

Reduction by heating with hydrogen and a nickel catalyst

How are aromatic amines formed from nitrobenzene’s

Reduction with tin and concentrated hydrochloric acid

Whats optical isomerism

A molecule which contains a carbon atoms bonded to four different groups which is not superimposable upon its mirror image

Whats are enantiomers

Pairs of optical isomers which are non-superimposable mirror images

Why do amino acids react with acids

Because they contain a basic (NH2) group

Why do amino acids react with bases

Because they contain an acid (COOH) group

What forms when amino acids are in aqueous solution and how

The acid group protonates the amine group forming a zwitterion

Why do amino acids

Because of the electrostatic attraction between the opposite charges on adjacent zwitterions

Why do amides have a neutral charge

Because the lone pair on the nitrogen is delocalised across the amide group and so cannot form a dative covalent bond to H+

How are carboxylic acids formed from amides

Through hydrolysis with aqueous acid

Whats addition polymerisation

When one unsaturated monomer joins together to form a saturated polymer

Whats condensation polymerisation

When two monomers join together to form a chain by eliminating a small molecule (waste or HCl)

How are polyesters usually formed

The condensation of dicarboxylic acids with diols

What conditions and reagents are needed to form a nitrile from an alkane

Sodium cyanide in ethanol

What sort of mechanism forms a nitrile

Nucleophilic substitution

What conditions and reagents are needed for the formation of hydroxynitriles from aldehydes

Sodium cyanide and hydrochloride acid

How are carboxylic acids formed from nitriles

Through hydrolysis with aqueous acids

What are the 5 steps to recrystallisation

1. Dissolve in the minimum quantity of hot solvent

2. Filter solution to remove insoluble impurities

3. Cool the filtrate to allow crystals to form

4. Filter the solution under reduced pressure to remove soluble impurities

5. Pure crystals are removed from the filter paper and left to dry

What compound is used as a standard in NMR spectroscopy

TMS

What’s chemical shift

The slight changed in signal position caused by the precise chemical environment of an atom in a molecule

What’s chemical shift measures in

Ppmn

What must be used so that protons in the solvent don’t appear in the spectrum

Deuterated solvents

What do the number of peaks show in Carbon NMR

The number of equivalent carbons present

What do the number of peaks in proton NMR tell you

The number of equivalent hydrogens in a molecule

What do splitting patterns in proton NMR tell you

The number of hydrogens on adjacent carbons

How can D2O be used to identify O-H and N-H peaks

The deuterium atoms will exchange with the hydrogen atoms removing these peaks

Whats the empirical formula

The simplest whole number ratio of atoms of each element present in a compound

What’s the molecular formula

The number of type of atoms of each element in a compound

Whats the general formula

The simplest algebraic formula of a member of a homologous series

What’s structural formulae

The minimum detail that shows the arrangement of atoms in a molecule

Whats displayed formula

Formula showing the relative positioning of all the atoms and all the bonds between them

Whats skeletal formula

The simplifies organic formula shown by removing hydrogen atoms from alkyl chains

Whats a homologous series

A series of organic compounds that have the same functional group and each successive member differs by CH2

Whats a functional group

A group of atoms responsible for the characteristic reactions of a compound

Aliphatic compounds

Compounds containing carbon and hydrogen joined together in straight chains or branched chains

Alicyclic compounds

An aliphatic compound arranged in a non-aromatic ring with or without side chains

Aromatic compounds

Compounds containing a benzene ring

Saturated compound

Compound containing single carbon-carbon bonds only

Unsaturated compound

Compounds containing multiple carbon-carbon bonds

Structural isomer

Compounds with the same molecular formula but different structural formulae

Whats a hydrocarbon

Compounds containing carbon and hydrogen only

How does the boiling point of alkenes change with the number of carbon atoms

The boiling point increases because there are more induced dipoles-dipole interactions which become stronger and require more energy to overcome

How does branching change the boiling point of alkanes

Branching decreases the strength of induced dipole-dipole interactions because of the reduced surface contact leading leading to a lower boiling point

What forms when alkanes are fully combusted

Carbon dioxide and water

What forms from then incomplete combustion of alkanes

Carbon monoxide and water

What are the reagents and conditions for the formation of haloalkanes from alkanes

Chlorine/bromine in UV light

What reaction mechanism forms haloalkanes from alkanes

Free-radical substitution

What sort of fission occurs in free radical substitution

Homolytic fission

Whats a radical

A species with an unpaired electron

What occurs during the initiation reaction

Cl2 → Cl.

What occurs during propagation reactions (use C2H6)

C2H6 + Cl. → C2H5. + HCl

C2H5. + Cl2 → C2H5Cl + Cl.

What occurs during termination reactions (use C2H6)

Cl. + Cl. → Cl2

C2H5. + C2H5. → C4H10

C2H5. + Cl. → C2H5Cl

Whats stereoisomerism

When compounds have the same structural formula but a different arrangement of atoms in space

Whats the E isomer

Where the higher priority groups are on opposite sides of the double bond

What’s then Z isomer

Where the higher priority groups are on the same side of the double bond

When can cis/trans isomerism occur

When two of the substituent groups attached to each carbon in the C=C are the same

Why are alkenes more reactive than alkanes

Because the pi bond in alkenes is weaker than the sigma bond in alkanes and so is more readily broken during reactions

What reagents and conditions are needed to form an alkane from an alkene

Heat with hydrogen and a nickel catalyst

What reagents and conditions are needed to form dihaloalkanes from alkenes

Halogen

Whats the test for unsaturated molecules

Using bromine water, unsaturated molecules will turn bromine water colourless

What reagents and conditions are needed to form haloalkanes from alkenes

Hydrogen halides

What does markovnikovs rule state

That when a hydrogen halide is added across the double bond of an alkene the major products will be the one where the hydrogen atom adds to the carbon which already has the most hydrogens

Why does the major product form when hydrogen halides are reacted with alkenes

Because the haloalkane formed from the most stable carbocation intermediate will form most readily

What reagents and conditions are needed to form alcohols from alkenes

Heated with steam in the presence of an acid catalyst (concentrated phosphoric acid)

Whats an electrophile

A species which accepts an electron pair to form a covalent bond

Heterolytic fission

Where a bond breaks and both electros go to the same atom forming an ion pair

Why are secondary and tertiary carbocations more stable than primary carbocations

Because they have more electron releasing groups

What are biodegradable polymers

Polymers made from plant material which can be broken down by microorganisms into water and carbon dioxide and biological molecules

What are photodegradable polymers

Oil based polymers which contain bonds which are weakened by light absorption allowing them to be broken down by light

Why is PVS hazardous

Because of the chlorine within it which can form HCl if burned

How can PVC be reused

By dissolving it in a solvent and reusing the precipitate formed

How can waste polymers be used as fuel

They can be incinerated and the heat produced used to turn a turbine and produce electricity

How else can waste polymers be recycled

By being used as feedstock

Why do alcohols have higher boiling points than other organic compounds

Because they can form hydrogen bonds because of the polar O-H group

What colour change do dichromate ions undergo when alcohols are oxidised

They’re reduced from orange to green

What reagents and condition are needed to form an aldehyde from a primary alcohol

Heating under distillation with acidified dichromate (VI)

What reagents and conditions are needed to form ketones from secondary alcohols

Heating under reflux with acidified dichromate (VI)