Organic Flashcards
(30 cards)
Which two groups do all amino acids contain?
Amino group (NH2) and a carboxyl group (COOH)
What is a zwitterion?
A dipolar ion with a positive charge on one end of the molecule and a negative charge on the other. They exist at an amino acid’s isoelectric point.
What reaction joins amino acids together?
Condensation reactions, forming peptide bonds.
What reaction breaks up proteins?
Hydrolysis
General formula of an alpha amino acid
RCH(NH2)COOH
What is an alpha amino acid?
Amino acids with both groups (NH2 and COOH) attached to the same carbon
Why are amino acids amphoteric?
They have basic properties due to NH2 and acidic properties due to COOH
How are ketones made?
Refluxing a secondary alcohol with acidified potassium dichromate ions
How can an alcohol be produced from a carbonyl compound?
Reduce the carbonyl using NaBH4 (sodium tetraborohydride)
What is the product when aldehydes are reduced?
Primary alcohols
What is the product when ketones are reduced?
Secondary alcohols
What type of addition reaction is reduction of aldehydes/ketones?
Nucleophilic addition. H- is the nucleophile
What chemical test can be used to identify a carbonyl?
Brady’s reagent: 2,4-DNP dissolved in methanol and concentrated sulphuric acid.
An orange precipitate will form if a carbonyl is present, the melting point of which is unique for each carbonyl compound.
Explain the delocalised model of Benzene
p-orbitals of all six carbon atoms overlap to form pi bonds
This creates 2 ring shaped clouds of electrons, one above and below the plane
All the bond lengths are the same
The electrons are delocalised, making it a very stable molecule
Why does benzene undergo electrophilic substitution?
The delocalised ring of electrons makes it stable and spreads out the negative charge
What is an electrophilic
A positively charged ion or polar molecule that is attracted to an area of negative charge, ie a high electron density
How does benzene react with halogens?
Benzene undergoes electrophilic substitution with halogens in the presence of a halogen carrier, so the electrophilic is substituted in place of a H atom.
How do halogen carriers work?
Halogen carriers accept a lone pair of electrons from the electrophile, making it more positive and therefore strong enough to attack the stable benzene ring.
How is nitrobenzene formed?
Warm benzene with concentrated nitric and sulphuric acid (sulphuric acid is a catalyst and generates NO2+ electrophile). Keep below 55 degrees Celsius for mononitration.
Phenol + NaOH = ?
Sodium phenoxide and water
2Phenol + 2Na = ?
Sodium phenoxide and hydrogen gas
Does phenol react with bromine water?
Yes. Bromine water will be decolourised, as the p-orbital on the oxygen overlaps with the delocalised ring and increases electron density.
How are aldehydes formed?
Heat and distill a primary alcohol with acidified dichromate ions (this is oxidation!)
What test can be used to identify an aldehyde?
Heat with Tollens reagent (silver nitrate dissolved in ammonia). Aldehyde is oxidised, silver is reduced and a SILVER MIRROR forms.
