Define Bronsted acid and base!
Broenstead acid: a substance that donates protons
Broensted base: a substrate that accepts Protons (Hydrogen)
Define the terms nucleophile and electrophile!
Define Lewis acid and bases and compare the concept!
Lewis concept of acid and base is based on the concept if a substance can accept electrons or donate electrons. It goes further than the common concept of Broensted-lowry.
A Lewis acid is a substance that accepts an electron of a Lewis base. Further, a lewis base is a donator of electrons
· Lewis acis must accept an electron pair
· therefore a vacant, low energy orbital is needed
· Various metal cations and transition metal are lewis acids
Describe the mechanism of electrophile addition of acid-catalyzed hydration of 2 methylpropene!
Compare the two major nucleophilic substitution reactions regarding formed intermediates and the type of substrates!
Carbonacid have a nd derivates:
alpha-position (heteroatom) can stabilize neg. charge
can act as a leaving group
-> nucleophilic substitution
aldehydes/ketone:
aplha position (C/H) cant stabilize negative charge
typical noc leaving group
-> nucleophilic addition
Name the two major groups of compounds bearing a carbonyl group and compare their reactivities!
Order the following compounds according to their reactivity starting with the most reactive species: thioester,amide,acyl phosphate and ester! Draw the functional group for each compound!
Name the three mechanism
Hyperkonjugation
In organic chemistry, hyperconjugation is an electronic interaction between a fully occupied orbital of a σ bond (usually a C-H or C-C bond) and a neighboring unoccupied or single occupied molecular orbital. The overlap of the two orbitals enables additional delocalization of the electrons from the σ bond, resulting in additional mesomerism stabilization.
Which AS exhibits predominantly a charged side-chain at pH 7 ?
Arginine, Histidine, Lysine, Aspatic acid, Glutamic acid
Which amino acid occurs most frequently in the active site of enzymes? Rationalize why this might be the case?
Explain why the cysteine is the most commonly occurring amino acid in covalent catalysis.
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