Functional Groups

• stoic number = # of sigma bonds attached to atom + # of lone pairs attached to atom

  • = 4 —> sp3 hybridized

  • = 3 —> sp2 hybridized

  • = 2 —> sp hybridized

• sigma bond = orbitals facing each other

• pi bond = orbitals not facing each other (parallel)

• acid base: kw = ka x kb

  • 14 = pka + pkb

    • use to subtract pkb to find pka of other side. The higher pka is the weaker acid, which is favored, so that side (react or prod) is favored.

• chiral: nonsuperimposable

  • center carbon, must have 4 bonds to 4 different groups attached

  • try taking mirror image to check

• enantiomers: stereoisomers that are mirror images of each other

  • stereoisomers: isomers that differ in the 3D arrangement if atoms

    • # of stereoisomers = 2^n where n = # of chiral centers

  • when drawing enantiomers, you can do 2 things

    • change dashes to wedges, and wedges to dashes and leave to og shape

    • draw the mirror image of the enantiomer

  • have same magnitude but different direction of rotation of polarized light

  • rotate plane of light in equal/opposite direction

    • clockwise - dextrorotary (d/D/+).

    • counter - levorotatory (l/L/+).

    • specific rotation [a] = (a(observed))/(c*l).

      • where c = concentration (g/mL).

      • where l = path length

    • racemic = 50:50 with no overall rotation: notation is (d,l)

      • form when achiral species react to give chiral product

• can ingold prolog convention: each chiral center is assign and absolute configuration R(clock), S(counter)

  • ID chiral center

  • assign priority to groups

  • rotate so lowest priority (usually H) is at the back

  • draw arrow from 1st priority to 3rd.

  • if arrow went clockwise - assign configuration R, if arrow went counter - assign configuration S

• Double bond becomes 2 single bonds to the same atom, triple becomes 3 single bonds

• newman projections: looking down a molecule

  • dot represents front carbon

  • circle represents back carbon

  • stablest = lowest energy = gauche interractions (staggered)

  • unstablest = highest energy = eclipsed (aligned with one another)

• hammond postulate: species similar in energy and structure have transition states that more closely resembles the structure of the closest stable species.

  • exo resembles reactants

  • end resembles products

  • bromination is endo

  • chlorination is exo

• free radicals:

  • carbon: sp2, single e- in p orbital, less than octet - electron deficient - 3º H is most stable

  • carbocations: completely empty p orbital - electrophilic/ strong acids - 3º H is most stable

  • carbanions: sp3, sp2, or sp, lone pair in one hybrid - formal (–) charge - nucleophiles/strong bases - Methyl is most stable

• all single bonds (sigma)

• ex: (linear)

  • methane (1 C) - CH4

  • ethane (2 C) - C2H6

  • propane (3 C) - C3H8

  • butane (4 C) - C4H10

• once exceded 6 carbons, there is a broader amount of ways to arrange the atoms

nomenclature:

Step 1: Number the carbons - first substituent should be closest to #1

Step 2: Note the position of each substituent - List First!

• ex: substituents are at carbons 3 and 5: list by saying 3, 5

Step 3: determine prefix (di, tri, tetra, penta, hexa, hepta, octa…) by how many of each substituent there are - List Second!

• ex: two of the same substituents: di

Step 4: identify substituents (by # of Cs: 1=methyl, 2=ethyl, 3=propyl/isopropyl, 4=butyl/isobutyl/secbutyl/tertbutyl).

• is iso when 3 carbons connected to one central

root: # of C in longest chain -

1: meth

2: eth

3: prop

4: but

5: pent

6: hex

7: hept

8: oct

9: non

10: dec

diastereomers = double bonds

• not mirror images

Multiple chiral centers:

• dif configuration at each center = enatiomers

• Dif at some = diastereomers

• max # of diastereomers = 2^n

Meso compound: achiral

• plane of symmetry

• mirror images

• not enatiomers