Organic Chemistry Reactions

Nucleophilic Substitution of Alkyl Halides

What type of reaction is this?

dehydrohalogenation

What type of reaction is this?

dehydration of alcohols

What type of reaction is this?

hydrohalogenation of alkenes

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acid-catalyzed hydration of alkenes

What type of reaction is this?

oxymercuration-demurcuration of alkenes

What type of reaction is this?

hydroboration-oxidation of alkenes

What type of reaction is this?

catalytic hydrogenation of alkenes

What type of reaction is this?

halohydrin formation from alkenes

What type of reaction is this?

dihalogenation of alkenes

What type of reaction is this?

anti-dihydroxylation of alkenes

What type of reaction is this?

syn-dihydroxalation of alkenes

What type of reaction is this?

ozonolysis- reduction/oxidation

What type of reaction is this?

Preparation of Alkynes from Alkyl Dihalides

What type of reaction is this?

Catalytic Hydrogenation of Alkynes

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Dissolving Metal Reduction of Alkynes

What type of reaction is this?

Hydrohalogenation of Alkynes

What type of reaction is this?

Acid-Catalyzed Hydration of Alkynes

What type of reaction is this?

Hydroboration/Oxidation of Alkynes

What type of reaction is this?

Halogenation of Alkynes

What type of reaction is this?

Ozonolysis of Alkynes

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Alkylation of Terminal Alkynes

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Radical Halogenation of Alkanes

What type of reaction is this?

Radical Hydrohalogenation of Alkenes

What type of reaction is this?

Radical Allylic Halogenation

What type of reaction is this?

What conditions do nucleophilic substitutions of alkyl halides occur in?

Cl, I (in place of Br), Many other nucleophiles

can be used.

What conditions do dehydrohalogenation occur in?

Various other strong or

weak bases possible (in

place of NaOCH3).

What conditions do dehydration of alcohols occur in?

HNO3, H3PO4, HClO4 or

other strong acids may be

used (in place of H2SO4).

• Water should be 'excluded'.

What conditions do Hydrohalogenation of Alkenes occur in?

HCl or HI may also be used

(in place of HBr) to make

other alkyl halides

What conditions do Acid-Catalyzed Hydration of Alkenes occur in?

HNO3, H3PO4, HClO4 or

other strong acids may be

used (in place of H2SO4) to

generate H3O+

What conditions do Oxymercuration-Demurcuration of Alkenes occur in?

1) Hg (OAc)2, H2O

2) NaBH4

What conditions do Hydroboration-Oxidation of Alkenes occur in?

R2BH can also be used in

place of BH3 (where R is an

alkyl group)

What conditions do Catalytic Hydrogenation of Alkenes occur in?

H2, Pt (of Pd)

What conditions do Halohydrin Formation from Alkenes occur in?

Br2 can be used (in place of

Cl2) to generate

bromohydrin instead of

chlorohydrin.

What conditions do Dihalogenation of Alkenes occur in?

Cl2 can be used (in place of

Br2) to generate dichlorides

What conditions do Anti-Dihydroxylation of Alkenes occur in?

Other peroxyacids

(CF3CO3H, mCPBA, etc.)

possible in step 1 in place of

CH3CO3H.

What conditions do Syn-Dihydroxylation of Alkenes occur in?

Catalytic OsO4 with NMO

can also be used (in place

of OsO4).

What conditions do Ozonolysis-Reduction/Oxidation occur in?

1) O3

2) H2O2

(alkene to carboxylic acid+ ketone)

1) O3

2) S(CH3)2

(Alkene to aldehyde+ ketone)

What conditions do Alkynes from Alkyl Dihalides occur in?

NaNH2, NH3 (excess)

Alkyl Dihalide to an alkyne

What conditions do Catalytic Hydrogenation of Alkynes occur in?

Pd/C catalyst possible in

place of Pt.

What conditions do Dissolving Metal Reduction of Alkynes occur in?

Na, NH3

What conditions do Hydrohalogenation of Alkynes occur in?

HBr

(excess), HCl or HI (in place of HBr)

provides the corresponding

dichloride or diiodide.

What conditions do Acid-Catalyzed Hydration of Alkynes occur in?

H2SO4, H2O,

HgSO4

What conditions do Hydroboration/Oxidation of Alkynes occur in?

1) BH3

2) H2O2, NaOH

R2BH can also be used in

place of BH3 (where R is an

alkyl group)

What conditions do Halogenation of Alkynes occur in?

Br2 (excess), Cl2 (in place of Br2) provides

the corresponding

tetrachloride.

What conditions do Ozonolysis of Alkynes occur in?

1) O3

2) H2O

What conditions do Alkylation of Terminal Alkynes occur in?

NaNH2,

CH3I

A variety of primary alkyl

halides can be used (in

place of CH3I)

What conditions do Radical Halogenation of Alkanes occur in?

I2, Br2, or F2 may be used

(in place of Cl2) to give the

corresponding halides.

What conditions do Radical Allylic Halogenation occur in?

NBS, (heat)

What conditions do Radical Hydrohalogenation of Alkenes occur in?

HCl, tBuOOtBu

ROOR (where R is other

alkyl or acyl) and AIBN may

also be used as radical

initiators.

When do nucleophilic substitutions occur?

SN2 proceeds in one

mechanistic step with

inversion of configuration.

SN1 proceeds through a

carbocation intermediate

(possibility for 1,2 shifts).

Preferred mechanistic

pathway depends on

several factors (reactant

sterics, nucleophilicity,

solvent, carbocation

stability, etc.)

When do Dehydrohalogenation occur?

E2 proceeds in one

mechanistic step.

E1 proceeds through

carbocation intermediate

(possibility for 1,2 shifts).

Site of deprotonation

depends on several factors

(mechanistic pathway, base

sterics, solvent, strength of

base used, substrate

conformation, etc.)

When do Dehydration of Alcohols occur?

Requires protonation of the

alcohol by acid, to convert

into a leaving group.

• With primary alcohols, the

reaction proceeds by E2

mechanism (no carbocation

intermediate).

• "Concentrated" (conc.) is

important. Water can't be

totally excluded, but should

be minimized to avoid

reversal of the reaction.

When do Hydrohalogenation of Alkenes occur?

The major product arises

from the more stable

carbocation intermediate

formed in the initial

protonation.

• Follows Markovnikov’s rule

• The intermediate may

undergo 1,2-alkyl or 1,2-

hydride rearrangement prior

to attack by the halide

When do Acid-Catalyzed Hydration of Alkenes occur?

Water is typically used as

solvent (in large excess).

• Mechanism is catalytic in

Bronsted acid.

• Follows Markovnikov’s rule

• The intermediate

carbocation may undergo

1,2-alkyl or 1,2- hydride

rearrangement.

When do Oxymercuration-Demurcuration of Alkenes occur?

This is a two-reaction

sequence.

• Water attacks the more

electrophilic carbon of the

mercurinium intermediate.

• Follows Markovnikov's rule,

but there is no carbocation

intermediate (and no

possibility for 1,2-shifts).

When do Hydroboration-Oxidation of Alkenes occur?

This is a two-reaction

sequence.

• Boron bonds to the less

substituted alkene carbon,

whereas hydride attacks the

more electropositive alkene

carbon.

• You only need to know the

mechanism for the first

reaction (hydroboration).

• This reaction provides the

anti-Markovnikov product.

• No carbocation intermediate

When do Catalytic Hydrogenation of Alkenes occur?

More substituted alkenes

react more slowly, with

tetrasubstituted alkenes

often failing to hydrogenate.

• Both hydrogens are added

simultaneously, to the same

face of the alkene (syn

addition).

When do Halohydrin Formation from Alkenes occur?

Water typically used as

solvent (in large excess).

• Water preferentially attacks

at the more electrophilic

carbon of the halonium ring

(more substituted carbon,

better stabilized partial

positive character).

When do Dihalogenation of Alkenes occur?

Formation of the bromonium

or chloronium intermediate

is concerted (no carbocation

intermediates).

• Halide anion attacks the

more electrophilic carbon of

the halonium ring.

When do Anti-Dihydroxylation of Alkenes occur?

This 2-step reaction

sequence involves

epoxidation followed by

acid-catalyzed epoxide ring

opening.

• Results exclusively in an

anti diol.

• SN2 ring opening occurs

selectively at the more

electropositive epoxide

carbon.

When do Syn-Dihydroxylation of Alkenes occur?

This is a 2-step reaction

sequence.

• Results exclusively in a syn

diol (both hydroxy groups

delivered to the same face

of the alkene).

When do Ozonolysis-Reduction/Oxidation occur?

Gives 2 moles of carbonyl

product(s) for every mole of

alkene starting material.

• S(CH3)2 in the second step

can give aldehyde or ketone

products.

• Aldehydes cannot be

products if H2O2 is used the

2nd step. H2O2 rapidly

converts any potential

aldehydes to carboxylic

acids.

When do Preparation of Alkynes from Alkyl Dihalides occur?

Involves 2 sequential E2

reactions.

• Halogens can be situated

on the same carbon

(geminal) or adjacent

carbons (vinical).

• Useful for the synthesis of

terminal alkynes, but not

internal alkynes.

When do Catalytic Hydrogenation of Alkynes occur?

Lindlar’s catalyst results in

the ‘cis’ alkene product (syn

delivery of only one

equivalent of H2).

When do Dissolving Metal Reduction of Alkynes occur?

Provides the trans alkene

resulting from anti addition

of two H atoms across the

triple bond.

When do Hydrohalogenation of Alkynes occur?

Use of 1 equiv of HX

provides the vinyl halide as

the major product.

• Both HX additions follow

Markovnikov's rule (halogen

add to the more substituted

carbon)

• Internal alkynes exhibit poor

regioselectivity.

When do Acid-Catalyzed Hydration of Alkynes occur?

Unlike alkene hydration,

HgSO4 is required to

accelerate the reaction.

• Carbonyl group is

generated at the more

substituted alkyne carbon

(Markovnikov selectivity).

• Proceeds through an enol

intermediate which

tautomerizes to the ketone.

When do Ozonolysis of Alkynes occur?

Gives 2 moles of carboxylic

acid product(s) for every

mole of alkyne.

• If the staring material is a

terminal alkyne, the reaction

generates CO2 as a

product.

When do Alkylation of Terminal Alkynes occur?

Reaction does not proceed

with secondary or tertiary

alkyl halides.

• Acetylene can be alkylated

twice (with excess base and

alkyl halide).

When do Radical Halogenation of Alkanes occur?

Heat is needed to

initiate homolytic cleavage

of the dihalide.

• Can give complex mixtures

of regioisomers.

• Use of excess dihalide

reagent often results in

multiple halogenations.

When do Radical Allylic Halogenation occur?

Heat is required to

initiate homolytic cleavage

of NBS.

• NBS allows you to minimize

the amount of Br2 present

during the reaction (large

amounts of Br2 would result

in dihalogenation of the

alkene).

• HBr (a byproduct of the H

abstraction step) reacts with

NBS to form a small amount

of Br2.

When do Radical Hydrohalogenation of Alkenes occur?

• Initiator starts the reaction

by facilitating the generation

of a halide radical.

• The more stable

(substituted) radical

intermediate is formed from

the alkene.

• This reaction provides the

anti-Markovnikov product.