MCAT-Orgo

• Enantiomers; mirror images 


  Nonsuperimposable
• Diastereomers, one but not all stereocenters differ in orientation. 


  Inverted stereoisomers
• Epimers, type of diastereomers that differ in spatial orientation at only one stereocenter


  One different stereocenter
• A separation technique used to monitor reaction progress when starting material and products have different polarities.


  Thin layer chromatography (TLC)
• Specific rotation


  Measures the direction and magnitude (angle) or rotation by which chiral molecules rotate plane-polarized light.
• Chiral molecules rotate plane-polarized light; the angle of rotation; known as specific rotation.


  Unique for each chiral molecule and must be determined experimentally.
• Polarimeter


  Instrument used to measure the rotation of polarized light.
• Bimolecular nucleophilic substitution (Sn2) reactions occur when a nucleophile donates electrons to an electrophile and the electrophile loses a leaving group


  SN2 reactions
• Halogens


  good leaving group
• Sn2 


  single step reaction where a nucleophile reacts with an electrophile, and a leaving group is simultaneously released from the electrophile.
• Electrophiles that are chiral centers undergo inversion of configuration in 


  Sn2 reactions
• Structural isomers (constitutional isomers)


  differ in how the atoms are connected at one or more points within the structure
• Stereoisomers; 


  Classified molecules based on spatial orientation
• Stereoisomers


  Diastereomers, enantiomers, conformational isomers
• Conformational isomers


  Rotation about single bond
• Racemic


  D,L
• Strecker Synthesis


  Synthetic (man-made) approach to prepare alpha-amino acids from aldehyde precursors
• Arginine = positive


  R
• Histidine = positive


  H
• Lysine = positive


  K
• Aspartic Acid = negative


  D
• Glutamic acid = negative


  E
• Serine = uncharged side chain


  S
• Threonine = uncharged side chain


  T
• Asparagine = uncharged side chain


  N
• Glutamine = uncharged side chain 


  Q
• pH = pka + log([A]/[HA])
• Indicator


  Changes color with changes in the pH but does NOT change the pH
• Z alkene


  Highest priority groups on the same side of double bond
• E alkene


  Highest priority groups on opposite side of double bond
• Zeff = Z - S

  Zeff = effective nuclear charge Z = protons and Z = core electrons
• Tyrosine (W)


  Neutral Polar
• Threonine (T)


  Neutral Polar
• Serine (S)


  Neutral Polar
• Asparagine (N)


  Neutral Polar
• Glutamine (Q)


  Neutral Polar
• Cysteine (C)


  Neutral Polar
• Histidine (H)


  Basic Polar
• Lysine (K)


  Basic Polar
• Arginine (R)


  Basic Polar