Reactions EXAM 3

Addition of HX (Mark)

• Add H and X

• Adds a halide

to more subst.

carbon.

Note: Look for hydride/methyl shift

Addition of HBr (Anti-M)

• Adds H and Br

• Br on less subst. carbon

• Can only use Br as halide

Dihalide Addition

• Add X and X

• Anti and co-planar

• Bottom reagent can be ROOR (peroxide)

• Trans

Halohydrin Reaction (Mark w/ OH)

• Add X and OH

• Anti and co-planar

• OH on more subst.

• KNOW MECHANISM

Forming alkene from vicinal dihalide

• Wedges with wedges

and dashes with dashes

• E2 Like!

• Take away Br and forms DB

Dehydration to alkene (non-terminal)

• E1 like and it cannot give terminal alkene

• forms DB

• Dehydrates to form terminal alkene

• forms DB

Additon of Oh (Mark and direct)

• Racemic mixture

• add OH only (Mark)

Oxymercuration/demercuration (OH mark w/o h2so4)

• add H and OH (mark)

• Anti

• trans

Oxymercuration/demercuration (OH mark w/ h2so4)

1.) H₃O⁺ / H⁺ / H₂SO₄

2.) H₂O

or

H₂SO₄ (dilute)

• add H and OH (mark)

• Anti

• If conc. H2SO4 —→ E1 rxn

Oxymercuration/demercuration (forming ethers Mark)

• add H and -OCH₃ (mark)

• Anti

• SPECIAL: Adds alcohol

  instead to form ethers!

Hydroboration Oxidation

• Add H and OH

• Anti-M

• syn

Catalytic Hydrogenation

• Add H and H

• syn

• Pay attention to steric factors

Glycol Synthesis from Alkene Oxidation (OsO4)

• Adding OH and OH

• syn

• can use NMO instead of H₂O₂

• treatment w/ HIO₄ does ring opening “ozonolysis”

Glycol Synthesis from Alkene Oxidation (KMnO4 cold)

• Adding OH and OH

• syn

• treatment w/ HIO₄ does ring opening “ozonolysis”

Glycol Synthesis from Alkene Oxidation (RCO₃H or MCPBA)

• Adding OH and OH

• anti

• KNOW MECHANISM

• Can also use 1.) MCPBA, CH₂Cl₂ 2.) H₃O⁺

Ozonolysis

• Cleaves the DB to turn C=C into C=O

• creates aldehyde or ketone or isolate molecule

• USE O₃ / DMS or (CH₃)₂S

Warm KMnO₄ Cleavage

• Cleaves the DB to turn C=C into C=O

• creates carboxylic acid or ketone

• *further oxidizes to form

  carboxylic acids

  *cannot isolate the

  formaldehyde

Carbene / Carbenoid addition (formation of cyclopropane)

• add CH₂ only

• syn

Oxidation of Alkenes: oxirane synthesis

• adds O to form epoxide

• syn

• mCPBA with nonpolar

  solvent can isolate

  oxirane

• treatment with H₃O⁺ forms OH and OH anti

Opening of Epoxides

• Adds OH and OH to epoxide

• Can simply use H₃O⁺ instead

• *acidic conditions opens

  from more substituted

  side.

• KNOW MECHANISM

Formation of Dibromocarbenes and Dichlorocarbenes

• Add CX₂

• Syn

• *please look up the

  mechanism so you can

  see how the carbene

  is formed

Formation of the acetylide anion

*forms the nucleophile that is handy when connecting carbons!

• Can use NaH as well

Using acetylide anion to form internal alkyne

• Forms internal alkyne R-≡-R

• Can introduce a long chain (i.e. CH₃CH₂CH₂Br)

• SN2

• 1° halides

• E2 rxn

• w/ 2° or 3° halides

• forms DB

Uses of the acetylide anion with carbonyl groups (ketones, aldehydes, and formaldehydes)

• adds OH group and R to carbonyl carbon

• *acetylide anion attacks

  partially positive carbon

  *DO NOT FORGET

  then H3O+

Synthesis of terminal Alkynes

*Need either geminal or

vicinal dihalides

*Look up mechanism

*NaNH2 FAVORS

terminal alkyne formation

Synthesis of internal Alkynes

*Need either geminal or

vicinal dihalides

*Look up mechanism

*KOH FAVORS

internal alkyne formation

Halogenation of alkynes (Br₂ and alkyne)

• Adds Br and Br to alkyne to make alkene

• Stereochemistry cannot be controlled

Halogenation of alkynes (HBr and alkyne - Mark)

• Adds Br and H to alkyne

• 1 eq makes alkene, 2 eq makes alkane

• Mark

• Syn

Halogenation of alkynes (HBr and alkyne - Anti M)

• Adds Br and H to alkyne

• Anti M

• Syn

• ROOR = peroxide

Catalytic reduction of alkyne with reactive catalyst

*Takes it all the way back

to alkane

*generally bad yield

Alkyne to Alkene: TRIPLE to DOUBLE BOND (cis alkene formation)

• Adds H and H to form cis alkene

• Syn (cis alkene formation)

• Dont worry about other reagents - just mention H₂ / Lindlar

Alkyne to Alkene: TRIPLE to DOUBLE BOND (trans alkene formation)

• Adds H and H to form trans alkene

• Anti (trans alkene formation)

Addition of H-OH to alkynes (forming ketone)

• Adds H-OH to form ketone

• Mark

• *If not terminal, you will

  get a mixture.

Addition of H-OH to alkynes (forming aldehyde)

• Adds H-OH to form aldehyde

• Anti M

Oxidation of alkynes (mild conditions)

• Adds O and O to make two carbonyls (ketones usually)

• *Forms vicinal

  carbonyls

  *further oxidizes terminal

  alkynes to form

  carboxylic acid.

Cleavage of Alkynes

• C≡C gets split into two COOH groups

• forms H2O and CO2 if terminal

• Can proceed via oxidation of alkyne (strong) or ozonolysis

The Grignard Reagent

• Add Mg to make R-MGBr

• adds to 1°, 2°, or 3° allyl, vinyl, or aryl carbons

The Organolithium Reagent

• Replace X with Li

• Acts like grignard but stronger

Formation of alcohols from Grignard (forming 1° alcohols)

• Adds R group to formaldehyde

• Acid workup step to make OH group

• *Know this mechanism!

Formation of alcohols from Grignard (forming 2° alcohols)

• Adds R group to aldehyde

• Acid workup step to make OH group

• *Know this mechanism!

Formation of alcohols from Grignard (forming 3° alcohols)

• Adds R group to ketone

• Acid workup step to make OH group

• *Know this mechanism!

Grignard and esters or acid halides

• Know from OCHEM LAB (synthesis of triphenylmethanol) !

• adding phenyl groups

• *Reaction goes until

  completion

  *Know this mechanism !

Grignard and Epoxides (opening of epoxides)

*SN2 like (attacks least

substituted side)

*Know this mechanism!

Attaching Deuterium to Carbons

*This is just good to

know.

Hydride reduction of carbonyls (mild conditions - NaBH4 as reagent)

*reduces ONLY

aldehydes and

ketones

*use alcohols as a

solvent.

*KNOW MECHANISM

Hydride reduction of carbonyls (strong conditions - LiAlH4 as reagent)

*reduces aldehydes,

ketones, esters, acid

halides, carboxyllic

acids (ALL Carbonyls)

*Use ethers solvents

*Acid 2nd step

*KNOW MECHANISM

Raney Nickel

• Reduces both carbonyl and alkene

Oxidation of alcohols 2° alcohols into ketones

• Makes ketone from 2° alcohols

Oxidation of alcohols 1° alcohols into carboxylic acid group

• Makes carboxylic acid from 1° alcohols

Oxidation of alcohols 1° alcohols into aldehyde/formaldehyde group

• Makes aldehyde from 1° alcohols

• *PCC is the only one

  that can isolate

  the formaldehyde.

Formation of the Tosylate Ester

• OH group replaced by OTos

*RETENTION from

where alcohol was

originally (SN2 purposes)

Formation of alkyl halide from 3° alcohols

• OH group replaced by X

• For 3° only

Formation of 1°/2° alkyl halides from 1°/2° alcohols

• OH group replaced by X

• For 2° and 1° only

*Basically an SN2

reaction. (Inversion

from original alcohol)

*Can also use SOCl2

for Cl, but it undergoes

a special mechanism!

Unique cleavage with HIO4 of syn vicinal diols

*Vicinal diols MUST

be syn

Formation of Alkoxide Anion

• Will be used for williamson ether synthesis

Williamson ether synthesis

• Using alkoxide anion, create ether

Ethers from intermolecular dehydration

• Another method of forming ether

• *MUST be identical

  alcohols or else you

  will get a mixture!!!

Pinacol - Pinacolone Rearrangement

*Need vicinal diols

*Know mechanism

(methyl shift!)

Fischer Estherification

*CAN USE ACID

HALIDE (i.e. CH₃COCl) instead of

carboxyllic acid!!!