ORGO Prelim 2

Harflerle yazilmis tek linelik name.

• Skeleton
• Corners and line ends represent Cs.
• Hs on Cs are invisible unless the C is written out. Then, we must also draw the Hs.
• Hs are drawn on heteroatoms.
• Lone pairs on heteroatoms are not necessary, but lone pairs must be drawn if they’re on C or are involved in a reaction.

-1

+1

-1

+1

+, - or 0

+.

Always show formal charges when drawing out molecules

Add all formal charges.

• Same molecular formula, different connectivity of their atoms.
• (chirals are excluded, as they’re optical isomers)

Functional group containing C=O

-SH

C-O-C

C-S-C

C-S-S-C

C-N-R

C=N-R

C triple bond N

• End with -al (propanal)
• C=O
• |
• H
• -COH

• O
• =
• C-C-C
• End with -one
• -C(CO)C

• -COOH
• -oic acid

• C double bonded to O
• Bonded to
• O
• Bonded to C
• Example: methyl ethanoate (the one bonded to the O is the first one)

• C double bonded to O
• Bonded to
• S
• Bonded to C
• Example: methyl ethanethiooate

• C double bonded to O
• Bonded to N-R
• -amide

• C=O
• Bonded to O
• C=O
• -oic anhydride

• P double bond O and single bond to 3 O
• PO4
• -phosphate
• One O bonds to a C
• Os can bond to other phosphates to form diphosphate etc.

• (2C+2)-H/2
• If DU = 0, saturated, alkane, no double bonds, no rings
• If DU = 1, unsaturated, 1 double bond or 1 ring

• Conjugate base of carboxylic acid.
• Module 2 and 3
• Prefix for 3 carbon?
• Prop

Hept

But

Non

Dec

• If two numbering schemes lead to the same branch numbers, the alphabetically lower branch should get the lower number.
• If you have a ring, everything sticking off is a branch

N-

• The concept that electrons/bonds are delocalized over 3 or more atoms which cannot be depicted in a single simple lewis structure. Only electrons can be moved, not atoms.
• Total formal charge is always the same.

• Check if there is a negative charge on an atom.
• If an adjacent atom has a double or triple bond, there is resonance.
• Check if there is a positive charge on an atom
• Does an adjacent atom have a lone pair or a double or triple bond.

The more the different resonance structures, the stabler the molecule is.

• Major contributor will have complete octets.
• Minimal formal charges
• And logical formal charges (the more electronegative atom has a negative charge)

• Ionic
• Hydrogen bonding (lone pair of a very EN atom bonded to an H that is bonded to a FON)
• Dipole-dipole
• dispersion/lonon/van der waals (proportional to surface area)

• Boiling point goes up as intermolecular forces goes up.
• If two molecules have the same intermolecular forces, the one with the greater number of C will have a higher boiling point.
• If they have the same number of C, the one with the more branches (higher surface area) will have the lower boiling point.

The molecule with H bonds will be the most soluble in water.

Hydrophobic, so insoluble in water

Ion or dipole dipole interactions will be water soluble if their hydrophobic regions are small enough.

• Alcohols, acids, amines are very soluble. (both donors and acceptors of h bonds)
• Ketones, ethers and aldehydes are soluble but not so much (just acceptors of H bonds)

• Ketones,
• Ethers
• Aldehydes

• Alcohols
• Acids
• Amines

• If all bonds are nonpolar, then nonpolar
• If molecule has 1 polar bond, then polar
• If molecule has multiple polar bonds and the dipole moments oppose each other, then the molecule is nonpolar. BUT make sure you check whether they oppose each other in a 3D space.

• What are conformational isomers?
• Various 3D arrangements of atoms that can be interconverted solley by rotations around single bonds. No moving electrons. Just spinning electrons.

• Using Newman projections.
• The dot is the front carbon, the circle is the back carbon. There are no invisible Hs.

• If the Hs are lined up directly behind each other, this is a high energy conformation.
• This is called ECLIPSED.
• If the Hs are not lined up, this is the lower energy conformation. This is called staggered.

Lowest energy possible with the Hs not lined up directly behind each other.

When the Hs are lined up directly behind each other in newman projections

• When methyl groups or something are next to each other but not lined up with each other (eclipsing)
• THis is higher in energy than staggered, but definitely lower in energy than eclipsed conformers.

On the same face of the ring (top or bottom)

On the opposite faces of the ring (top or bottom)

Sticking up or down parallel to an axis.

Sticking to the sides of the ring (east, west)

Everything that was axial becomes equatorial, but top/up remains the same.

• Bulkier groups prefer equatorial positions. Given a choice, put smaller groups axial and bigger groups equatorial.
• Carbons are bigger than non carbons.
• Branched is bigger than non branched
• T-butyl group is huge. There is extreme preference to but this as equatorial (c bonded to 3 methyl groups)

• If not equatorial, then higher energy.
• If everything is axial, cis one is higher energy due to diaxial interactions.

• When the angle between the two largest groups in the newman projection is 180 degrees.
• What are stereoisomers?
• All atoms are connected in the same order, but with different arrangement of atoms/bonds in 3D space.
• Conformers are a type of stereoisomer that can be interconverted by rotating around single (sigma) bonds.
• Can’t be enantiomers without an asymmetric carbon.

• Mirror image, non super imposable stereoisomers
• Boiling point, melting point, solubility are equal, but they rotate plane polarized light in opposite directions.

Opposite configuration at 1 or more but not all stereocenters.

Opposite configuration of one out of many chiral centers.

• Molecules with an internal plane of symmetry, which makes R S the same as S R.
• Meso compounds are always R S

• A cross with the top being arms away from you and the sides being arms towards you.
• Common for sugars.

• Achiral molecules
• OR racemic mixture

• d (+) is to the right
• l is to the left (-)
• But there is no obvious correlation between 3D arrangement and direction of light rotation

A molecule that has an enantiomer.

A molecule whose mirror image is superimposable.

• Rank priority of 4 groups (larger atomic number = higher priority, double bond is counted as bonded to that molecule twice)
• Place #4 in the back, or if it is the highest priority, switch S to R in the end
• Draw arrows 1-2-3, if clockwise R, if counterclockwise S

• Draw bisecting line across double bond
• Assign priorities to each “end” using the same rules as R/S
• If they’re on the same side, Z (zusammen)
• If they’re on opposite sides, E (entgagen)

Reactants must collide in the correct orientation with enough energy.

• No intermediate (single step reaction), concerted addition to one face of the double bond (H2 with Pt or something) cis addition
• Intermediate (triangle), stepwise addition to opposite faces (cyclic bromonium ion (+) with (-)
• Intermediate (carbocation + sp2 + p hybridization) stepwise addition to either face. (HCl,), H is added first to either side in either orientation, the other C becomes +. We understand which C it gets added to through Markovnikov’s rule. The Markovnikov’s rule states that H gets added to the C with more Hs.

Requires input of energy

Outputs energy

Transition state

Intermediate.

Conc. of products / conc of reactants

More products than reactants, exergonic reaction

More reactants than products, endergonic reaction

• Are faster
• Not the rate determining step
• Position of equilibrium DOES NOT change with catalysts

• Make rxns go faster but are not consumed
• DO NOt change the position of equilibrium, stabilize the transition state and lower the Ea

• The more carbons around a carbocation, the more it is stabilized by the inductive effect.
• Tertiary is more stable than secondary which is more stable than primary which is more stable than methyl

E- shift toward a positive charge through sigma bonds.

The carbocation with higher stability (more c bonded to it) will be preferentially formed.

Resonance is a more powerful stabilizer than induction. If you’re asked which molecule is more stable, check if any have resonance. IF not, tertiary is most stable.

The transition state looks more like whatever it is closer to in energy.

• Acids are proton donors
• Bases are proton acceptors.

You must have a free lone pair to act as a base.

The stronger the acid, the more deprotonated at equilibrium (loves giving away protons)

PH = Pka + [deprotonated]/[protonated]

Molecule is predominantly deporonated

Molecule is predominantly protonated

Molecule is 50:50 deprotonated to protonated

• Deprotonated: 0
• Protonated: +

• Protonated: 0
• Deprotonated: -

90 % deprotonated

99 % deprotonated

90% protonated

99% protonated

• Neutral (uncharged) molecules can cross membranes and charged molecules cannot.
• Acids are nearly 100% deprotonated (-) at 7.4
• Bases are only 90% protonated (+) at 7.4

• PI = PH at which the average net charge = 0
• For aminoacids with acidic side chains, the PIs will be the midpoint of the two lowest pKas.
• For amino acids with basic side chains, PI will be the midpoint of the two highest Pkas.
• For amino acids with non ionizable side chains, PI = midpoint of the acid and base PkAs.

• Contain a positively polarized H (binded to O or S)
• Or H bonded to C next to a carbonyl (C=O)

Contains both + and - charges and net charge is 0

The more stable the resulting base (lower energy, through induction or resonance) the stronger the acid.

• EN molecules (such as Cl, F etc.) bonded to C cause inductive effect and stabilize the - charge on the conjugate base, thus making the acid stronger.
• This has a positive relationship with proximity to negative charge, electronegativity of the atoms, and the number of electronegative atoms.

• Conjugate bases of weak acids are strong bases. The weaker the acid, the stronger the base.
• Nitrogens with lone pairs are good bases. AMIDES aren’t, since their electrons are tied up in resonance.

Protons next to a C double bonded to O.