Module 6 Flashcards
What is the retention factor in chromatography and how is it calculated?
Retention factor (RF) = distance moved by the component / distance moved by the solvent front
Distance moved by component must be measured from the middle of the component
Solvent front = where the solvent has moved up to on the paper
What is NMR spectroscopy and how does it work?
NMR = Nuclear Magnetic Resonance
How NMR works:
Compound is hit with x-rays and resonates a certain wavelength depending on what is attached to each molecule
What is a chiral centre?
Chiral centre = a carbon where a different group is attached to each part of it - common in amino acids
How do amino acids react in different environments?
In an acidic environment the amine basic “side” reacts In an alkaline environment the carboxylic acid acidic “side” reacts
How do aldehydes and ketones react with different compounds?
With NaBH4: Aldehydes reduce to primary alcohols Ketones reduce to secondary alcohols With CN-: Both aldehydes and ketones reduce to hydroxynitriles Nucleophilic addition mechanism (with CN-)
What are the mechanisms for nucleophilic addition?
What are optical isomers?
Two compounds that have the same molecular formula but are mirror images of each other
How do you test for aldehydes and ketones?
Testing using 2,4-DNP: Both aldehydes and ketones produce an orange precipitate Testing using Tollens’ reagent (AgO dissolved in NH3): Aldehydes form a silver precipitate All other carbonyl groups have no change
What are the different directing groups?
2-4-6 directing - once a 2-4-6 directing compound is added to the benzene compounds can only be added to the 2nd, 4th or 6th carbon - electron donating - activating
3-5 directing - once a 3-5 directing compound is added to the benzene compounds can only be added to the 3rd or 5th carbon - electron withdrawing - deactivating
What is the structure and properties of benzene and how do you name compounds that have a benzene ring?
Benzene does not turn bromine water colourless The circle is the constant movement of pi bonds - the pi bonds in the double bonds join together to form one large doughnut-shaped ring above and below the compound When bonds move around rapidly (like in benzene) resonance is created Benzene has a lower bond enthalpy than double bonds but a higher bond enthalpy than single bonds When naming compounds with a benzene ring always count the carbons in a clockwise rotation If benzene is not the main group it changes to phenyl- instead of -benzene or benz-
What are the different reactions with benzene?
How are primary, secondary and tertiary amides identified?
Each one represents how many carbons are attached to the nitrogen Primary = one carbon bonded to nitrogen Secondary = two carbons bonded Tertiary = three carbons bonded (no hydrogens bonded to nitrogen)
How are primary, secondary and tertiary amines identified?
Each one represents how many “R” groups (groups that aren’t hydrogen) are present on the amine Primary = one R group (two hydrogens present) Secondary = two R groups (can be different) Tertiary = three R groups (no hydrogens on the amine)
What are the different properties and reactions with phenol?
Phenol has more electrons present so it is easier to add on compounds through electrophilic substitution. Phenol will create a white precipitate when added to bromine water instead of decolourising it. Phenol is activating - it makes the benzene more reactive and more likely to be involved in an electrophilic substitution reaction Phenol is a weak acid
How do carboxylic acids react?
Carboxylic acid → H+ + carboxylate ion Carboxylic acids react with carbonate ions to fizz and create carbon dioxide
What is the mechanism for electrophilic substitution?
