MTIAgenda Meso finishing up stereochem

Chirality DIE nomenclatureAcid Base

Meg one compound w

2 chiral centerssame 4 groups on both chiral centersR S or S n

l I

en 819 4 OH O150 1 0 2 A LOH1 1 12 BdayHO OH

Internal Mirror Meso superimposable on mirrorPlane image

m

Samemolecule 0A HO

HNotchiral

If a molecule Is choral It rotates

the plane of plane polarized light in a concentration

dependent manner Rotation in clockwisedirection t

counterclockwise nN

n 19

I E H tUnpolarited Polarizer Polarized RotatePlane

light 4pointed light

Interactsselectivelywith ChoralMolecules

Two enantiomers win rotate polarized light in theopposite direction but to equal extents

If B enantiomer rotates 41.70S enantiomer 41,70

R t R i can't getfrom rotation dineton

Lb D ONLY represent structural similarities

Nowadays CPD do not mean I z T

Think Tgs r s S

A racemic mixture won't rotate the plane ofpolarized light

B I mixture of 2 enantiomers

A compound is optically active if it rotates

the plane of polarized light48 racemic mixtures and meso compounds

are not optically active

i Messyou can have chiral 0

Artemis planecenters In an qm Not a chiralachiral molecule molecule

Acid Base HtAcid Proton DonorBase Proton Acceptor

HIEI Nato A E HEH jNato

A lBase Coffey Conjugate Ban

We can describe mathematically how far a

reaction proceeds by defining an equilibrium constant

equilibrium arrows say Ad keg

A F BB interconvert

Keg tells us which

kegsEff PrEIIITs side ants

US

productsRightsideis favored atequilibrium

If keg I equal amounts of A's B

keg D No A present all B

keg 0008880 lots of A v little B

For Acids k Bases i A A B FA B A

Acid Base Conj Conj

Ka CAP BeitBan Acid

G i3Since ka values range from 101 us ol05FkasD48 we use log scale to make thee As smaller

g

pKAs logoKA

Ka's pka tell us how much an acid will be

protonated us deprotonated at a specific pH

pka B k reflect a given acid'sINTRINSIC ability to protonate thebae

which is H2O

for pkA kA

SmallerLower pkavalues 7mm StrongerAddMoreNegative If0H El stable weak

superstrong Conjugateacid Conj

Barcoo Bases

pka 7 Ha

f Equilibrium favors formation of the WEAKER ACID46for a given pair of acids the smalleflowertheplea the stronger the acid

A stronger acid will react to form a morestableMorestable Cong Base Anion

A given acid will be proto if the

PI of the solution is than the A

of the acid

0H A H E H A H q H

conj HAcid Bun

HA AO

If pH pka feud Conj Base

pH pka Add L Gonia Base

pH pka Awd Koni Ban

Afl is mostly protonated

jNHAdThmeuwwtpDorABase

determines whether a molecule

µfunctions as an acid or a base

It Depends

The number of protons an sps hybrid N atom

is bound to changes w pHTan lowpH means

a dusolution

lots of If aroun

If there are a lot of protons in Sobibor acidic

N will be omoreH R YEHH

then B thereaverelativelyfewerlt r p HH

or0

R E HLets follow 100 amore R MHD molecules in solutionas we raise pH from 0 very acidD to pH 50

super basoD

Consider two relevant pleas R Fitz pka 40

R NHz pka 40

pH 0 pH 10 pH 15

100R BHsfsor.iqw

dem.YPH40ypH5012 MHz 100 R inHz 50 R WH

PHI PHI 100 0

99 90RNAs p 50 RIFF R IH1 10 RNHL go pints

Acid constant conj.B.amTaken A 066

H2OIf pH 1.7 mostly

Azo

pH ATHmoser a

fmogflypH 92

Acid Conj Ban

A init in Th LP mostly

mostlypH40 pH 40

In Human Body pH itCarbongve

Generic Amino And AzN Q8 Aurers

47deprotonated

pka 10 R RdQoHplantAmmu Protonated pH7 Aminepisobonated

ruins 9EfEEfhpka NIO

More on thenegative chargeOn a move E N atom

On an atom w7 more s characterjp spa Sp

Compareacross 33 5 25 5

of a large atomImansingleStabilized by resonance delocalization coignsizeStabilized by induction from nearby EW elements

Rank the following acids I most audio 4 leastacidic

Acid H2O CHy NHS H2S

EE a Ei 0in A

zbesscE.mil mgYdanafaooanisEsbebrgger

BestOption

frompka tableHI City NH HD

pka 15.7 51 40 8 9

2

Rank the following acids I most audio 4 leastacidic

Wsop oH TEKOH KoH

4 2 I 3a I

A Resonance is in play in

af of them

0 not on halogens so size rule 3 isirrelevant

TWve i pulling of 8 densitythrong

F bonds by E N atoms groups