Module 6 Flashcards
What is a stationary phase (in chromatography)?
The phase that doesn’t move
What is a mobile phase (in chromatography)?
The phase that does move (through the stationary phase)
What reagents are required to halogenate benzene, and what kind of reaction is it?
Electrophilic substitution, requiring FeBr3 (to form Br+ electrophile), or the equivalent Fe-halogen compound
What reagents are required to alkylate benzene, and what kind of reaction is it?
Electrophilic substitution, requiring a haloalkane and a halogen carrier (e.g. FeCl3)
What is produced when an acyl chloride reacts with ammonia?
A 1” amide
What reagents are required to nitrate benzene and what kind of reaction is it?
Electrophilic Substitution reaction, requiring nitric acid and sulphuric acid (to form NO2+ electrophile)
How can you hydrolyse polymers?
Acid (NaOH + H2O) or base (H+ + H2O) hydrolysis
How can you turn a carbonyl into a hydroxynitrile?
add hydrogen cyanide (or make it in situ)
How can you form hydroxynitriles from a carbonyl compound?
Add sulphuric acid and sodium-cyanide (to form hydrogen cyanide in-situ) - good for increasing chain length
What effect(s) does the NO2 (nitro) group have on the benzene ring?
It ‘deactivates’ it, making it less able to react with electrophiles and also directing to position 3 substitutions
How can you reduce a Ketone?
2[H] (from the NaBH4) and water, to produce a secondary alcohol
How could ethylamine act as a base?
Accept a proton to become an ethylammonium ion
Describe the structure of the delocalised model of benzene?
Adjacent p-orbitals overlap sideways to form a ring of electron density above the below the plane of bonding (known as a pi-system)
How do you bromate phenol and what type of reaction is it?
Electrophilic substitution, add 3Br2, no catalyst is required
How can you test for a carbonyl group?
Add Brady’s reagent (2,4-DNP in methanol and sulphuric acid), if positive, a yellow/orange ppt forms
What does phenol ‘behave as if it were’?
A weak acid, it can partially dissociate protons from its hydroxide group
What is the name of the product (an ester) of the reaction between ethanoic acid and methanol?
Methylethanoate
How does a zwitterion behave at a pH higher than its isoelectric point?
As an acid, the inverse is true also
How can nitriles be hydrolysed?
Add water and HCl, under heat
What evidence is there to reject the Kekulean model of benzene?
Relatively unreactive
- Benzene does not undergo electrophilic addition or decolourise bromine water as it would if there were double bonds
Carbon-carbon bond length
- X-ray diffraction has shown all of the bonds to be the same length (a length in between single and double)
Hydration Enthalpies
- The enthalpy of hydrogenation is less than 3x that of cyclohexene (which would be the expected value if Kekule was right)
What reagents are required to acylate benzene, and what kind of reaction is it?
Electrophilic substitution, requiring an acyl-chloride and a halogen carrier (e.g. FeCl3)
How can nitriles be reduced into animes?
Add H2 with a Ni catalyst
In gas chromatography, what is the stationary phase and what is the mobile phase, and how are the results presented?
Stationary Phase: Boiling Liquid
Mobile Phase: Carrier Gas (and sample mixture)
Output is ‘retention time’
How can carbonyls react by nucleophilic addition with NaBH4, and how with NaCN?
Where an intermediate is formed and then protonated, making an alcohol or a hydroxynitrile respectively
