Unit 4 Flashcards
Acyl chlorides + water form?
Carboxylic acid + HCl gas (misty fumes)
Acyl chlorides + alcohol ->
Ester + HCl gas
Acyl chlorides + concentrated ammonia
Amide (-CONH2) + HCl
Further reaction to NH4Cl
Acyl chlorides + primary amine
N-substituted (RCONHR’) + HCl
Acyl chlorides + secondary amines ->
N,N-disubstituted amide (RCONH(R’)(R”) + HCl
Carboxylic acid + alcohol ->
In presence of acid catalyst (H2SO4) ester + H2O
Physical properties of esters
Low boiling point
Insoluble in water
Pleasant smells
Carboxylate salt (-COO-) COO with negative charge and a positive ion + H2SO4 ->
Carboxylic acid + metal salt
Types of reverse esterification
Acidic hydrolysis
Alkaline hydrolysis
How to do acidic hydrolysis in esters
Ester + warm water -> (acid catalyst H2SO4) carboxylic acid + alcohol
It is an equilibrium for and backward arrow needed
Alkaline hydrolysis in esters
Ester + NaOH -> carboxylate salt + alcohol
Complete reaction
What happens in condensation polymerisation
Diol (two OH groups at each end + dicarboxylic acid -> polyester + H2O
OH from COOH and H from OH (Acyl chlorides can be used to form HCL)
Stationary phase in chromatography
Liquid/ solid that does not move
Mobile phase in chromatography
Liquid moves through stationary phase transporting the substance tested
How do mobile and stationary allow chromatography to separate solvents
Chemicals more attracted to stationary phase and only slightly attracted to mobile phase will move less up the paper
Mobile phase in Paper chromatography
Solvent
Mobile phase in TLC chromatography
Solvent
Stationary phase in paper chromatography
Water trapped in the fibres of chromatography paper
Stationary phase in TLC chromatography
Sheet of glass coated with silica or alumina
Stationary phase of column chromatography
Alumina or silica soaked in solvent
Mobile face in solemn chromatography
The solvent added when pouring the mixture of top of the stationary phase
How is HPLC chromatography different to column chromatography
Solvent is forced through HPLC tube by high pressure
Stationary phase in HPLC chromatography
silica
What does a polar substance attract
Polar molecules
Mobile phase in HPLC chromatography
Hexane (non-polar)
How are the different components measured in HPLC chromatography
By the absorption of UV light measured
What state are the substances being measured in HPLC chromatography
Liquids
What does Gas and HPLC measure
The retention time- time taken to detect the separation of components
What is the mobile phase in gas chromatography
Inert gas
What is the stationary phase in gas chromatography
The solid/liquid coated in the inside of tube
How those the stationary phase affect the retention time
The weaker the attraction to stationary phase the shorter the retention time
What does C13 NMR measure
Number of different chemical environments
(Peaks show different groups the carbon are connected to)
Physical properties of Carboxylic acids
High boiling point which increase with Mr
Soluble but this decreases as chain length increases
Oxidation reaction to make -COOH
Primary alcohol or aldehyde + acidified potassium dichromate with acid catalyst under reflux -> -COOH
What does the hydrolysis of Nitriles produce
-COOH + another compound
Types of hydrolysis of nitriles
Acidic hydrolysis
Alkaline hydrolysis
Describe acidic hydrolysis of nitriles
1 step
Nitrile + dilute acid (H+) + H2O under reflux -> -COOH + NH4+
Describe alkaline hydrolysis of nitriles
2 steps
Nitrile + NaOH + H2O under reflux -> -COO-Na+ + NH3
Further -COO-Na + H+ -> -COOH
Reducing COOH
COOH + LiAlH4 in dry ether -> primary alcohol
Halogenation of -COOH
-COOH + PCL5 in anhydrous conditions -> -RCOCl +POCl3 + HCl which results in misty fumes
Esterification of -COOH
-COOH + -OH (acid catalyst) -> ester + water
Neutralisation of -COOH
-COOH + OH- (strong alkali) -> carboxylate salt + water
Reduction of aldehydes
Aldehydes + LiAlH4 in dry ether -> primary alcohol
Oxidation of aldehydes
Aldehyde + acidified potassium dichromate + conc. acid under reflux -> -COOH
This will produce a colour change from orange to green
Reduction of ketones
Ketone + LiAlH4 in dry ether -> secondary alcohol
Oxidation of ketones
Ketones are not easily oxidised
Test to distinguish from ketones and aldehydes
Fehlings solution: Deep blue to red ppt
Tollens reagent: Colourless solution to silver mirror
What does the triodomethane (iodoform) test for
CH3CO group
Present in ethanal and methyl ketones
Iodoform test equation
Methyl ketone + iodoform in alkaline sol. -> CHI3 (pale yellow ppt)
Conditions and product of nucleophilic addition of Carbonyls + HCN
Happens in alkaline solution containing KCN
Makes hydroxynitriles
What is 2,4-DNPH used for
It is a test which through nucleophilic addition forms an orange ppt with carbonyl compounds
It’s derivatives ( chemicals produced) can be filtered, purified, dried and melting point determined
What is Sn1
Nucleophilic substitution
Seen in tertiary halogenoalkanes
Has 2 steps
Has one species in RDS
What is Sn2
Nucleophilic substitution
Seen in primary halogenoalkanes
With 1 step (has transition stage)
Has 2 species in its RDS
What is the end-point of a titration
The colour change from the indicator which is past the equivalence point at an imbalance of acid or base
What is the equivalence point in a titration
The exact proportions of acid and base in the titration
Ph of equivalence point titration of strong acid + strong base
Ph=7
Ph of equivalence point titration of strong acid + weak base
Ph= <7
Ph of equivalence point titration of weak acid + strong base
> 7
where can’t the equivalence point be determined
In the titration of weak acid with weak base because there is an absence of sharp decrease in the graph, only a point of inflection
How do indicators work
Through dissociation
HI -><- I + H+
therefore when [H]=[In]
[H] = KIn
What are buffer solutions made out of
Weak acid/ base and their conjugate base/ acid
Assumptions made when calculating pH of buffer solutions
Remember to add up volume!
-dissociation is negligible
-conc of acid and salt is half when volume is doubled
