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Orgo 1 Reagent Sheet Answers:
Alkene Addition & Rxns: This section will utilize one starting material that is treated with different reagents to see how each is affected by different reagents. This helps you see similarities and differences between reagents. Underneath is an area to take notes on the reagent that will help you remember the mechanism/what the reagent does.
Notes:- “Hydrohalogenation”: addition of HX; X= Cl,Br, I- H and X added Syn or Anti (X attacks from front or back)- Carbocation intermediate (1,2 hydride/methyl shift to stabilize carbocation)- Markovnikov addition
Notes:- Anti-Markovnikov addition of X and H; X= Cl & Br- Peroxide allows for anti markovnikov addition- Occurs via radical reaction mechanism, ROOR initiator- Radical intermediate (similar to carbocation)- No resonance- Syn and Anti addition of H and X
Notes:- “Halogenation”: adds X2; X=Cl, Br, I- Halonium ion bridge intermediate - Anti addition of X2
Notes:- “Halohydration”: adds OH and X; X=Cl, Br, I- Adds OH on most substituted- Halonium Ion Bridge intermediate; no rearrangement- Anti addition of X and OH
Notes:- Adds OH and Br, specifically- Adds OH on most substituted- Bromonium Ion Bridge intermediate; no rearrangement- Anti addition of Br and OH
Notes: - “Acid Catalyzed Hydration”: adds H and OH- Markovnikov- Carbocation intermediate (1,2 hydride or methyl shift to stabilize carbocation)- Syn and Anti addition of H and OH
Notes:
- “Oxymercuration-demercuration”: adds OH and H- Markovnikov- Mercurinium ion intermediate (looks like an Hg bridge), no carbocation
arrangement - Anti addition of H and OH
Notes:- “Hydroboration-Oxidation”: adds OH and H- BH2 bridge intermediate: syn addition of BH2 and H, followed by oxidation of
BH2 to OH with retention of configuration- Syn addition of OH and H
Notes: - “Anti- dihydroxylation”: OH’s bound from opposite side- Epoxide formation then hydrolyzed from backside
Notes: - “Syn Dihydroxylation”: OH’s bound to same side
Notes:- “Catalytic Hydrogenation”: Syn addition of H2
Notes:- “Oxidative Cleavage”: cleaves double bonds into aldehydes and ketones- Draw a line down the middle of double bond, add oxygen on either end of it, and leave
rest of molecule attached to the double bond
Alkyne Reactions:
Preparing Alkynes:
Notes:
Notes:- Cis alkene forms because one equivalent of H2 is added cis to each other
Notes:- completely reduces Alkyne to an alkane
Notes: trans alkene forms because one equivalent of H2 is added trans from each other ( if you rotate one side and H’s are both facing up, one is on a wedge and one on a dash)
Notes: - X= Cl, Br, I- 1st addition results in trans addition of X2 because of halonium ion bridge and
backside attack on adjacent carbon resulting in ring opening
Notes:- X= Cl, Br, I- 1 addition results in trans addition of X2 Because of halonium ion bridge and
backside attack on adjacent carbon resulting in ring opening- This is major product observed
Notes: - Addition of X and H- Markovnikov- Carbocation intermediate on more substituted end of double bond
Notes:- Addition of 2 equivalents of HX- Markovnikov geminal dihalide- Carbocation intermediate on more substituted end of double bond for both
additions
Notes:- Addition of Br - Anti-Markovnikov - Radical intermediate
Notes:- Markovnikov addition of OH and H BUT tautomerizes to form ketone
Notes: - Anti Markovnikov addition of H and OH BUT tautomerizes to form
aldehyde
Notes: - “Ozonolysis” of an internal alkyne results in 2 carboxylic acids with their
respective R groups
Notes:- “Ozonolysis” of a terminal alkyne results in a carboxylic acid and carbon dioxide
Notes:- Alkylation of terminal alkyne- Removes H of end and replaces it with R group- Can do it again for other end of alkyne
Radical Reactions:Initiators:
Notes: start a radical reaction
Notes: - Chlorination: fast reaction so multiple monohalogenation products produced- Radical intermediate- Adding Cl to chiral center (left product) from either side (dash or wedge)- No resonance
Notes:- Bromination: slow reaction so only more stable product formed- radical intermediate- Adding Br to a chiral center results in addition of Br from either side (dash and
wedge)- No resonance
Notes:- Allylic Bromination- Resonance occurs to ensure radical intermediate most stable addition of Br- However, not favorable for allylic brominations because of a possible
halogenation reaction between Br2 and the double bond
Notes: - Allylic Bromination- Resonance occurs to ensure radical intermediate most stable addition of Br- This is more favorable because no side halogenation reaction between Br2 and
the alkene is competing.
Alcohols:Forming alcohols via reduction:
Notes: - “Catalytic hydrogenation” : reduces carbonyls to alcohols and double/triple bonds
to alkanes.
Notes:- NaBH4 = Sodium Borohydride- Selectively reduces aldehydes and ketones ONLY to alcohols (primary and
secondary, respectively)
Notes:- “LAH”= lithium aluminum hydride- Reduces aldehyde, ketones, carboxylic acids and esters to alcohols.- Aldehydes, ketones and carboxylic acids reduces to primary alcohols- Ketones reduce to secondary alcohols
Notes:- reduction of carboxylic acid to a primary alcohol- Need excess lithium aluminum hydride
Notes: - reduction of ester to primary alcohols - Need excess lithium aluminum hydride
Preparation and Using Grignard Reagent:
Notes:- treat any alkyl halide with Mg and an ether (typically diethyl ether) to create
Grignard reagent.
Using Grignard Reagent
Notes:- treating aldehyde or ketone with a Grignard reagent results in addition of an
alcohol and new R group.- Secondary (aldehyde) or tertiary (ketone) alcohol formed
Notes: - treating carboxylic acid or ester with excess Grignard results in tertiary alcohol
Notes:- use a protecting group when performing Grignard synthesis with an alcohol
present on molecule.
Notes:- replaces OH to Cl in one step (SN2 rxn)- Inversion of configuration
Notes:- changes OH to Br in one step (SN2)- Inversion of configuration/ backside attack
Epoxides and Ethers
Preparation of Ethers
Notes:- creating ethers from alcohols, an SN2 reaction- X= Cl, Br, or I- R2= any unhindered alkyl group or methyl group (only primary or methyl alkyl
halides)
Notes:- “Alky Oxymercuration-demercuration”- Markovnikov- H and OR added anti to each other
Reactions of Ethers:
Notes:- If R group primary or secondary, substituted via SN2 reaction mechanism.
Inversion of configuration (backside attack)- If R group tertiary, substituted via SN1 mechanism. Front or backside attack. - Cleavage doesn’t happen in R groups is aryl or vinyl
Preparation of Epoxides:
Notes:- Not enantiomerselective (both enantiomers displayed)- Retention of configuration
Notes:- not enantiomerselective, both enantiomers - Retention of configuration
Notes: - to make epoxide stereoselective- use (+) DET to make epoxide from above- Use (-) DET to make epoxide from below
Ring opening With Nucleophile and Water
Notes:- SN2 mechanism so nucleophile attacks less substituted side of the epoxide- Backside attack
Ring opening in acidic conditions:
Notes: - X= Cl, Br, I- If between a primary and secondary carbon, the halide will attack the primary
Notes:- X=Cl,Br, I- If between primary or secondary carbon and a tertiary, the halogen will bind to
tertiary