Organic Chemistry midterm 1

Most EN atom

F (4.0)

constitutional isomer

same formula different connectivity

EN order of F, N, Cl, H, C, O, Br

F>O>N=Cl>Br>C>H

EN and Charge stability

More EN = more stable bond

Resonance Structure Significance Rules

1) octet rule 2) fewer formal charges 3) negative charge for high EN, positive for low EN

resonance structure patterns (4)

1) allylic lone pairs 2) allylic carbon-containing cations 3) polar multiple bonds 4) benzene rings

major/minor

degree contribute to resonance hybrid

significant/insignificant

whether contributes to reactivity

valid/invalid

break/not octet rule

hybridization

mixing of atomic orbitals to make new orbitals

nitrile

alkyl halide

alkene

alkyne

alcohol

ether

thiol

sulfide

aromatic

ketone

aldehyde

carboxylic acid

acyl halide

anhydride

ester

amide

amine

HOMO

highest occupied molecular orbital

LUMO

lowest unoccupied molecular orbital

stronger acids have ___ pKa values

lower

pKa O⁺H (protonated carbonyl)

-7

pKa H₃O⁺

-2

pKa carboxylic acid

5

pKa 2 ketones (alpha to 2 carbonyls)

9

pKa NH₄⁺ (ammonium)

10

pKa H₂O (to OH^-)

15.7 (14)

pKa alcohol

16-19

pKa ketone next to methyl (alpha to carbonyl)

19

pKa NH₃ amine

35

pKa alkane

50

pKa equation

how to determine acidity on structure

stability of negative charge

CARIO

Charge Atom Resonance Induction Orbital

CARIO: Charge

positive charge molecule = stronger acid (neg for base)

CARIO: Atom bearing the charge

1) more EN = stronger acid, acids often -OH 2) bigger atom = more acidic (down group)

CARIO: Resonance

1) conjugate base resonance = stronger acid 2) c-h bond to carbonyl (ketone) more acidic

CARIO: Induction

more acidic if more EN atom attached to charged atom (more if closer to H released)

CARIO: Orbital

more acidic C if lower hybridization (sp>sp3)

isopropyl

sec-butyl

tert-butyl

iso-butyl

relative stability of alkanes

more branched = more stable = lower heat of combustion

stereoisomer vs constitutional isomer vs different conformations

consitutional isomer: ONLY same formula, different atom arrangement

stereoisomer: same formula + atom arrangement, different 3D spatial arrangement (break pie bonds or chiral center)

different conformations: SAME MOLECULE just rotate around single bond

C-substitution terms (eg primary C)

conformations

rotation around single bond, same molecule

stereoisomers

same formula and bond connection, different 3D shapes; convert by breaking pi bonds; DIFFERENT COMPOUNDS