DAT Organic Chem

amphiprotic

molecule that can act as either acid or base

higher pH

more basic, more -OH

lower pH

more acidic, more H+

pKa and Ka values

increase Ka = decrease pKa

low pKa = high acidity = low pH

Rank Acids and Bases with CARDIO

Charge: more positive charge, more acidic. more negative charge, more basic

Atom: acidity increases from left to right across row (EN), and doing down the columns (atom size)

Resonance: increases stability of charge

Dipole Induction: electrons sucked away by withdrawal group makes it easier for H+ to leave (increase acidity), donating groups push electrons (decrease acidity)

Orbitals: more s-orbitals an atom has, more EN, more acidic. sp orbitals from triple bonds make the H more acidic than sp³ orbitals from single bonds

pH and Amino Acids

have carboxylic acid and amine group

pKa < pH = depronated molecule (missing H+)

pKa > pH = pronated molecule (filled with H+)

lower pH = more pronated

Configurational Isomers

Z vs E

cis vs trans

conformational isomers

Newman projections

anti-staggered, eclipsed, gauche staggered, total eclipsed

Naming Alcohols

1) parent chain is longest chain with -OH group

2) add -ol to end of parent chain

Naming Ethers

1) parent chain is whichever is the longer side on the O

2) name substituent on other side and add - oxy

Naming Amines

primary amine: add the suffix -amine to the parent chain

symmetrical amine: add di- or tri- to alkyl group

asymmetrical secondary or tertiary amine: the longer side is the parent group, add -amine, name substituents with prefix N-

naming aldehydes

1) parent chain is longest group that has the carbon with the double bond to O

2) replace -e with -al

naming ketones

1) name the parent chain replace -e with -one

2) number which carbon the double bond to O is

Naming Carboxylic Acids

1) parent chain is longest containing carboxylic acid

2) replace -e with -oic acid

Naming Acid Halides

1) replace -e with -oyl “name of halide”

4-methylpentanoyl iodide

naming esters

1) alkyl group atatched to single bonded O is listed first with suffix -yl

2) parent chain follows counting away from double bonded O, replace -e with -oate

ethylbutanoate

Naming Amides

1) group attached to nitrogen gets prefix N-

2) parent chain attached to double-bonded O replace -e with -amide

N-propyl butanamide

Naming Acid anhydrides

1) list both sides in alphabetical order, replace -e with -oic

2) add anhydride at end

butanoic propanoic anhydride

Naming Nitriles

add suffix -nitrile

pentanenitrile

Naming aromatics

1) give lowest number to highest priority group

2) use common name for the benzene and then add other substituents

1-chloro-2-methyl benzene or 2chlorotoluane

Naming spiro alkanes

spiro [a,b] parent name

parent name: total number of carbon atoms

a,b: number of carbons to the left and right of the center carbon: list lowest to highest

Bicyclic Alkanes

bicyclo [a,b,c] parent name

parent name: total number of electrons

a,b,c: number of carbons to the left, right, and above the center carbon: list highest to lowest

constitutional isomers

same chemical formula but different connectivity and location of atoms

enantiomers

mirror image

diastereomers

Non-mirror images

1) cis/trans isomers of ringed compounds

2) cis/trans or E/Z isomers of alkenes

3) molecules with multiple stereocenters that do not have exact opposite R/S forms

chiral centers

R: clockwise

S: counterclockwise

counting stereoisomers

2ⁿ

chirality (optical activity)

uses polarimeter to rotate plane-polarized light

L molecules: clockwise

D molecules: counterclockwise

physical properties of enantiomers

are the same and cannot tell apart

meso compounds

two or more stereocenters with a line of symmetry

dirrections cancel each other out to become achiral

fischer projections

IR Spectroscopy

x-axis: wavenumber, cm^-1

y-axis: transmittance, %

UV-Vis Spectroscopy

tells if the molecule has conjugated bonds: back and forth double then single bonds

Mass Spectrometry

determine compounds mass

sprays e- at the molecule, they stick to parts and give slightly negative charge, move towards pos side of tube, can break apart in pieces but weight adds up to the whole molecule

molecular ion of mass spectrometry

parent peak, complete molecule

base peak in mass spectrometry

most stable ion produces tallest peak, most abundent

Bromine in mass spectrometry

50% of all Br weigh 79 and 50% weigh 81

Chlorine in mass spectrometry

75% of all Cl weigh 35 and 25% weigh 37

Degrees of unsaturation

each double bond, ring, or triple bond (2)

C_nH_2n+2 Then subtract oringinal formula from this.

Ignore Oxygen, add one for every Halogen, subtract one for every Nitrogen

Divide by 2

C-NMR Spectroscopy

shows where different kinds of carbons show up on the graph

use symmetry to determine number of unique carbons

positively charged carbons

more left on C-NMR

“de-sheilded”

negatively charged carbons

more right on C-NMR

“sheilded”

C-NMR Chart

Carbons ppm

alkane 0-70

alkene 90-120

aromatic 110-160

carbonyl carbons:

_{esters, amides, carboxylic} 160-180

_{aldehydes, ketones} >200

H-NMR Spectroscopy

peaks produced by different kinds of hydrogens

more pos, more left

more neg, more right

H-NMR Chart

Hydrogens ppm

alkane 1-4

alkene 4-6

aromatic 6-8

aldehyde 9-10

carboxylic a 11-14

alcohol 1-5

amine 1-5

integrals of H-NMR

number above peak that shows how many of that kind of hydrogen

splitting

hydrogen A looks to its neighbor and sees how many hydrogen Bs there are. Count all neighbooring hydrogens and add 1

SN1

occurs in two steps

the more stable the carbocation intermediate, the more likely to occur

weak nucleophiles allow rxn to occur

rearrangements can occur

produces racemic mixture of enantiomers

rate = k[electrophile]

SN2

one step reaction

no carbocation formed

rate = k[electrophile][nucleophile]

become more reactive with less carbons bonded to middle carbon

strong nucleophiles required

inversion of sterocenter

For substitution reactions:

The larger the atom (Cl, Br, I)

the better the leaving group

E1

produces an alkene

likes a weak base

two step reaction

rate = k[electrophile]

zaitsev’s rule

give the more substituted carbon the double carbon bond and favor the E-alkene

E2

one step reaction

likes a strong base

rate = k[electrophile][nucleophile]

E alkene is major, Z alkene is minor

more substituted the carbon in the LG, the more likely to react

more branching in relation to melting point

increased melting point

more branching in relation to boiling point

decreases boiling point

melting point detector use

use to determine compound and compounds purity (match to literature)

Extraction with Separatory Funnel

separates polar compounds (aqueous layer) from nonpolar substances (organic layer)

purifys product from water soluble contaminants

for most reactions the organic layer is on top

Acid and base extractions

carboxylic acids and phenols: do not dissolve in aqueous layer. first deprotonate with a strong base (NaOH) to make it soluble in the aqueous layer. Then separate and add acid (HCl) to make it protonate which then will precipiate out of the aquous layer

amines: first protonate with acid to make it water soluble then separate layers and add base to deprotonate and make it precipitate

distillation

separate mixtures of 2 or more boilable liquids (volatile)

liquid with lower bp goes to to condensor then changes to liquid and goes to different funnel

fractional distilation

separate volatile liquids with boiling points that are 25 degrees Celsius apart

uses series of flasks

sublimation

impure mixture of salts in the flask, put test tube with ice to block the hole, boil compound in flask and solid turns to gas, hits cold test tube and turns solid again

recrystalization

Dissolved solids become less soluble when solvent is cools

scratch glass to provide nucleation site

not for volatile liquids

Gas-Liquid Chromatography

heat mixture of compounds to boiling and then push them using a gas down a coiled tube, separates individual components by boiling point

detector measures which component travels furthest in and how much comes out

Thin-Layer Chromatography, TLC

Separate compounds by solubility in solvent, by polarity

the most soluble compound travels furthest up the plate

dot shows the highest (more nonpolar) vs the lowest (more polar) compound

plate is coated with a polar substance, solvent at bottom is nonpolar

good for following a reaction’s progress

retention factor, Rf

polar compounds, smaller rf

nonpolar compounds, larger rf

solvent specific, increase rf by adding more polar solvent

column chromatography

fill glass cylander with silica gel (white powder). add impure mixture to top.

add organic solvent (eluent) to the top

it will gradually separate by polarity with the most polar compound traveling the shortest distance and the most nonpolar compound eluding the furthest

Hydrohalogenations

adding HX to an alkene

acid-catalyzed hydration

adding H+ and -OH to alkene

product is an alcohol

Oxymercuration-Demercuration

does the same thing as acid-catalyzed hydration but does not do rearrangements

anti-addition, markovinkov, -OH adds to the most substituted carbon

acid-catalyzed alcohol addition

adds H+ and HOR group to alkene

Markovnikov, rearrangements possible

Halogens to Alkenes

adds X₂ to an alkene

Markovnikov, anti-addition, no rearrangements

Halogens with Water to Alkene

add X₂ with water. adds an alcohol functional group

Hydroboration Oxidation

adds an alcohol functional group to the least substituted carbon in the double bond

anti-markovinkov, syn-addition (cis), no rearrangements

Hydrobromination with Peroxide

HBr plus peroxide added to alkene

anti-markovinkov, forms radicals no rearrangement

Epoxidation

adds mCPBA to create ring with oxygen

anti-dihydroxide

Adding nucleophile to an epoxide

in basic conditions: nuc attacks the least substituted carbon

in acidic conditions: the oxygen attacks H+ first, then the nuc goes to the most stable bond and breaks the ring

Syn (cis) dihydroxide

add OsO₄ and peroxide to the double bond

creates a vicinal diol with cis -OH functional groups

Ozonolysis

using O₃ to cut the alkene in half

each side is double bonded to O

Ozonolysis with Zn/H2O or (CH3)2S workup

each half of the alkene is double bonded to O

ozonolysis with H2O2 workup

each half of the alkene is bonded to O but then one of the hydrogen atoms bonded to the double bonded carbon gets replaced with -OH

ozonolysis with KMnO4/H3O (hot.conc) workup

internal alkenes: does the same thing as O3/H2O2

terminal alkenes: turns the outside CH2 into O = C = O

Oncolysis with HIO4

1) OsO4 used to put two -OH on each carbon of the alkene in cis figuration

2) use HIO4 to create ketones (=O) out of those -OH groups.

KMnO4 without acid

Baeyer’s reagent (neutral KmnO4) does same thing as OsO4 with peroxide

alkyne ozonolysis

creates carboxylic acids from the two halfs

basic KMnO4/H3O does the same thing with internal alkynes

terminal alkynes: makes the outside CH into CO2

Catalytic Hydrogenation of Alkenes

Adding H₂

uses metal catalyst (Pd, Pt, Rh, or Ni) to form cis alkane

Catalytic Hydrogenation of Alkynes

uses metal catalyst (Pd, Pt, Rh, Ni) to form alkane

Lindlar’s catalyst makes a Z alkene

Na or Li with NH₃ at -78 degrees Celsius forms an E alkene

Addition reactions with alkynes

typically anti-addition giving E-Alkene

Hydrohalogenation

internal alkyne: bind to either side to create two forms of the halide product

terminal alkyne: halides bind to the most substituted carbon

Di-Halogenation

adds X₂ to alkyne, with excess forms alkane with four halogens bonded to it

Hydrobromination with Peroxide

alkyne adds HBr and H2O2 to add the Br in an anti-Markovnikov addition

Acid-Catalyzed Hydration of Alkyne

Alkyne adds H20, H₂SO₄ and HgSO₄ to form an enol and then proceed through tautomerism to form a ketone

Hydroboration Hydration for Alkynes

alkyne added to BH₃/THF or (Sia)₂BH/THF with H2O, H2O2, -OH to form anti-markovinkov enol which tautomerism to become aldehyde

Alkylating Alkynes

NaNH₂ removes the H from the terminal alkyne. creates an acetylide (alkyne with negative carbon group)

able to go through substitution reactions to add carbons on the chain

Alkylating Alkynes with ketones

alkyne adds to the carbonyl carbon of the ketone and then the double bond of the carbonyl transfers to the O to have a negative charge, then the negative oxygen takes a H+ from water to become an alcohol

Alkylating Alkynes with an epoxide

negative acetylide combined with epoxide and the negative oxygen takes a H+ from water to become an alcohol

Forming Alkynes from Alkanes

can be done with vicinal halides or geminal halides

use NaNH₂ (sodamide) to take the H+ away and kicks the Halogen to create a double bond the excess takes the other H+ to form the alkyne and kicks the halogen

kinetic product

forms fastest

comes from the most stable carbocation intermediate

favored at low temperatures (kinetic control: -40 degrees Celsius or lower)

Thermodynamic product

forms slower

favored at high temperatures (thermo control: 0 degrees Celsius or higher)

forms the most substituted alkene product (most internalized)

most stable product due to Zaitsev’s rule

Zaitsev’s rule

alkene with the largest number of non-hydrogen bonds on its C=C bond is the most thermodynamically stable

the most substituted, the most internalized