Organic Chemistry (All Reactions)

SN2 Reagents/Solvent

Strong nucleophile (Negative Charge/Polarizable) (HI, HBr, NaCN, RS-, RO-) + Haloalkane. Favored by a polar aprotic solvent (DMSO, DMF, THF, Acetone). Aprotic solvents wont hydrogen bond w/ the nucleophile, resulting in less stabilization.

SN2 Rate Law

Rate = k[Substrate][Nuc]

SN2 Description

Nucleophilic attack at the leaving groups site, very sensitive to steric hindrance, results in inversion of configuration if the resultant product is chiral. Happens through “backside attack”

SN2 Substrates

Less substituted is preferred. Never occurs with 3’.

E2 Reagents/Solvents

Strong Base (Unhindered: NaOH, NaOMe, NaOEt/ Hindered: t-BuOK, LDA, DBN, DBU). Polar aprotic solvents (DMSO, DMF, acetone, THF) for LDA/THF OR polar protic counterparts for alkoxide (NaOH/H2O, NaOMe/MeOH, NaOEt/EtOH)

E2 Rate Law

Rate = k[substrate][base]

E2 Description

Concerted mechanism that involves the base removing a beta-hydrogen. Important consideration is that this beta hydrogen must be ANTIPERPLANAR to the leaving group. This CAN occur through single bond rotation. Pi bond forms leaving group leaves at the same time. Irreversible arrows. Small bases select for the Zaitsev product while bulky bases produce the Hoffman as the major product. if there are 2 hydrogens, the trans/E isomer dominates over the cis/Z isomer.

E2 Substrate

Tertiary is preferred, then 2’, then primary.

SN1 Reagents/Solvent

Weak Nucleophile (naH, H2O, MeH, EtOH, ROH, strong acids (aq) also work). Solvolysis (Solvent is the nucleophile)

SN1 Rate Law

Rate = k[Substrate]

SN1 Description

Stepwise process (2-3 steps). First, leaving group leaves and forms a carbocation intermediate. Nucleophile attacks from each side an produces a racemic mixture. Rearrangements will occur (HS/MS). Reversible arrows. Slight excess of inversion product.

SN1 Substrate

3’ ideally, 2’ is rare. Never methyl or 1’ UNLESS rearrangements will occur.

E1 Reagents/Solvent

Weak base. Neutral solvent (H2O, ROH) + HEAT. Or Strong acid.

E1 Rate Law

Rate = k[Substrate]

E1 Description

Stepwise (2 steps). Carbocation intermediate formation first. Then weak base takes the beta hydrogen. Must be antiperiplanar. Rearrangements occur. All steps are reversible except rearrangements. Always gives Zaitsev as Major. Trans isomer > cis isomer.

E1 Substrate

3’ or 2’. Never with 1’ or methyl unless a rearrangement is possible.

Hydrohalogenation

Adds H & X across double Bond. Markovnikov addition. When 1 new chiral center created - Racemic mixture. When 2 New Centers created - diasteromer mixture

Hydrohalogenation Reagents

HX

Hydrobromination with Peroxide

Anti-markovnikov addition of H and Br across a double bond.1 new Chiral = Racemic. 2 new chiral - diasteromers

Hydrobromination w/ Peroxide Reagents

HBr, H2O2 (ROOR)

Acid-Catalyzed Hydration

Markovnikov addition of the OH. if a chiral center created, racemic. Rearrangement can and will occur.

Acid-Catalyzed Hydration Reagents

H2SO4 (Dilute), H2O

Oxymercuration-Demurcuration

Add H & OH to make a Markovnikov alcohol. Even tho 3 ring intermediate formed and technically anti addition, the product is racemeic because of the radical step. Used to AVOID rearrangment

Oxymercuration-Demurcuration Reagents

1) Hg(OAc)2, THF, H2O

2) NaBH4, H2O

Hydroboration-Oxidation

Antimarkovnikov addition of OH. Hydroboration creates a trialkylborane (BR3). Reason for antimarkovnikov results from the least substituted carbon being able to attack B easier, while the H shifts to the partial positive carbon. H and OH added to same side, syn addition. Syn enantiomers formed if theres a chiral center

Hydroboration-Oxidation Reagents

1) BH3 . THF

2) H2O2, NaOH, H2O

Catalytic Hydrogenation

Adds 2 H’s across double bond to form an alkane. Syn adddition, H’s added to the same face. Watch for meso compounds.

Catalytic Hydrogenation Reagents

H2 gas + Metal catalyst (Pt, Pd, Ni)

Halogenation

Add X and X. Makes a dihaloalkane. Stereospecific, only Anti addition occurs. Racemic trans mixture forms

Halogenation reagents

Br2/Cl2 in inert solvent

Halohydrin Formation

Adds X and OH. 100% anti addition. X and OH end up trans to eachother. Markovnikov addition of the OH.

Halohydrin Formation Reagents

Br2 + H2O

Epoxidation and Anti Dihydroxylation

Adds two OHs anti to eachother. The epoxide is the intermediate, which is a 3 member ring and is the reason anti addition occurs. Its a redox reaction technically.

Epoxidation and Anti Dihydroxylation Reagents

RCO3H (MCPBA) for epoxidation. For both: MCPBA and H3O+

Syn Dihydroxylation

Adds 2 OHs syn. Watch for meso compounds

Syn Dihydroxylation Reagents

1) Os4 (cat.)

2) H2O2/NMO

Ozonolysis

Splits double bond into two carbonyls

Ozonolysis reagents

1) O3

2) Zn/H2O (reducing agents… DMS also works)

1 eq Hydrohalogenation (alkyne) w/ Reagents

1 eq HX

Non Nucleophilic Solvent

Markovnikov addition

2 eq Hydrohalogenation (alkyne) w/ Reagents

xs HX

Nonnucleophilic solvent

Markovnikov addition. Creates a geminal dihalide. termolecular process Rate = k[Alkyne][HX]²

Acid-Catalyzed Hydration (Alkyne)

HgSO4, H3O+ (H2SO4/H2O)

Markovnikov. The resulting product is an unstable enol, so tautomerization occurs.

Hydroboration-oxidation (Alkyne)

1) sia2BH or 9-BBN or THF

2) H2O2, H2O, NaOH

Forms an enol that tautomerizes. Syn addition occurs

1 eq Halogenation (Alkyne)

1 eq X2

Inert solvent

Anti addition occurs because it goes through a 3 ring ion intermediate. Anti matters because it will form a trans-dihaloalkene

2 eq Halogenation (Alkyne)

xs X2

Inert solvent

Technically anti addition. however, does not really affect the outcome.

Ozonolysis (Alkyne)

1) conc. O3

2) H2O

Splits across triple bonds and creates carboxylic acid

Alkylation of Acetylides

1) NaNH2, NH3(l)

2) RX in ether

Start with terminal alkyne, form an ion, adds R group to the end of the alkyne

Dissolving Metal Reduction

Na, NH3(l)

Anti addition

Adds 2 Hs anti. Creates a trans alkene. This step stops catalytic hydrogenation at the second step.

Catalytic Hydrogenation w/ Poisoned Catalyst

H2, Lindlars

Syn addition of 2 hydrogens, creates a cis alkene.

Catalytic Hydrogenation

H2, Pt

Turns alkyne into an alkane

Elimination (double dehydrohalogenation)

1) xs NaNH2 (2 eq for internal, 3 eq for terminal)

2) H2O

Tetrahalogenated alkane forms an alkyne