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