Unit 4 Extra Flashcards
Name the mechanism of the nitration of benzene
Electrophilic substitution
What allows 2,4-DNPH to react as a base
The lone pair of electrons on the N atoms
What is seen when 2,4-DNPH is used to identify an aldehyde or ketone
Orange/red solid
Why is 2,4-DNPH an appropriate reagent to use for identification of aldehydes and ketones
The derivatives formed have a precise melting temperature for identification
Recrystallisation
• dissolve impure solid in a minimum volume of hot solvent in a water bath
• allow to cool and then filter it off and dry
Now is nitric (III) acid prepared
Sodium nitrate (III) and HCl
Reagents used for iodoform test
NaOH/I2
Why would an amino acid be insoluble in methanol
It exists as a zwitterion and ionic compound are not generally soluble in covalent solvents
How does condensation polymerisation differ from addition polymerisation
Condensation polymerisation- a small molecule is eliminated
Addition polymerisation- no elimination
What other than carbonyls can decolourise acidified potassium manganate (VII)
Alkenes
Catalyst that can be used for hydrogenation of alkenes
Nickel
What is meant by the term radical
A species with an unpaired electron
State the type of mechanism occurring when bromine is added across the double bonds of an alkene
Electrophilic addition
Why is the melting temperature of an amino acid melting temperature much higher than other molecules of a similar size
They exist as zwitterions and so has strong ionic character therefore much stronger forces between molecules
Mechanism occurring in nitration of benzene
Electrophilic substitution
Equation that binds frequency and wavelength
c=fgamma
Equation that bind energy and frequency
E=hf
Why is something colourless in terms of the electromagnetic spectrum
It does not absorb in the visible region
What colour has the shortest wavelength in the visible spectrum
Violet
Which colour has the longest frequency in the visible spectrum
Red
Reagents necessary to produce an amine from a nitrate
Tin and concentrated hydrochloric acid
Differences between condensation polymerisation and addition polymerisation
• in condensation polymerisation a small molecule is eliminated, this does not occur with addition polymerisation
What are stereoisomers
Isomers with the same structural formula but biffer in the way the bonds are arranged in space
Why can E-Z isomerism occur
There is no rotation about a double bond
Evidence for delocalised structure of benzene
• all bonds same length
• enthalpy of hydrogenation means benzene is more stable than suggested by kekule structure
• benzene tends to react by substitution not addition
