MCAT Organic Equation Sheet We’ve helped over 50,000 students get better grades since 1999 … enough to do this NaBH 4 not strong enough to do this CARBONYLS AND AMINES Carbonyl reactions: … MOLECULAR STRUCTURE Hybridization: an atom is SP 3 hybridized if it contains only single bonds (tetrahedral geometry) 109.5 o an atom is SP 2 hybridized if it contains 1 double bond (trigonal geometry) 120 o an atom is SP hybridized if it contains 2 double bonds or 1 triple bond (linear, 180 o)***NOTE*** this only works for neutral atoms a …

Naming alkenes : E or Z When an alkene is tri- or tetra- substituted, E/Z nomenclature is used. To do this, each substituent across the double bond is assigned a priority according to the Cahn-Ingold-Prelog rules: (i) Rank according to atomic number of attached atom (Br>Cl>O>N>C>H) (ii) If the above rule does not solve the ranking, look at 2nd, 3rd, 4th, atoms away to try and find a difference in atomic number (iii) Multiple-bonded atoms are equivalent to the same number of single- bonded atoms High Low High Low Low High High Low Z- on the same side E- on opposite sides Assigning stereochemistry to chiral centers : ? substituents are ranked according to the Cahn-Ingold-Prelog rules (E/Z alkenes) Once substituents have been ranked, the lowest ranked is aimed away from the viewer (i.e. into the page). – If the remaining 1st, 2nd and 3rd ranked substituents are arranged: (i) Clockwise: R Stereochemistry (ii) Counter-clockwise S Stereochemistry Racemic mixtures : equal (50:50) mixtures of two enantiomers; often denoted by (+/-) Enantiomers have identical physical properties but diastereomers do not. Meso compounds – molecules that have at least 2 stereocentres BUT are achiral because they have a plane of symmetry. Fischer Projections: A C BD A C D B = – most highly oxidized group at the top (position A) – longest carbon chain is vertical (A to C) – Can rotate 180° but not 90 or 270° – Can hold one substituent in place then rotate others either clockwise or counter-c.w. isomers (have the same molecular formula) structural isomers (also known as constitutional isomers) – have a different bonding arrangement of atoms ex. H 3 C C H 2 H 2 C CH 3 H 3 C CH CH 3 CH 3 sterioisomers (have the same bonding arrangement of atoms but a different 3-D arrangement of atoms) geometric (also know as cis/trans) or Z / E Cis/ZTrans/E ***NOTE*** a conformation is a rotation of a bond or a flip of the chair in cyclohexane – double bonds in a ring can’t have cis/trans isomers – double bonds with 2 of the same substituents on the same carbon can’t have cis/trans isomers ex. can’t have cis/trans isomers chiral centers (also known as steriocenters or stereogenic centers) – occurs at an sp3 hybridized carbon with 4 different substituents…

Download MCAT Organic Equation Sheet.pdf