Chemistry - Organic - Reactions and Mechanisms

Alkane → Haloalkane reaction name

Radical Substitution

Alkane → Haloalkane reactants + conditions

X₂, UV

Alkane → Haloalkane initiation (* = radical)

X₂ UV> X* + X*

Alkane → Haloalkane propagation (* = radical)

X* + C_nH_2n+2 → *C_nH_2n+1 + HX

C_nH_2n+1 + X₂ → C_nH_2n+1X + X*

Alkane → Haloalkane termination (* = radical)

X* + X* → X₂

X* + *C_nH_2n+1 → C_nH_2n+1X

*C_nH_2n+1 + *C_nH_2n+1 → C_2nH_4n+2

Haloalkane → Alcohol reaction name

Nucleophilic Substitution

Haloalkane → Alcohol reactants + conditions

warm NaOH_(aq), reflux

Haloalkane → Alcohol mechanism (^& = partial charge)

curly arrow from ^-:OH to C^&+ joined to X

curly arrow from C-X bond to X^&-

products show OH replaces X and X^- is formed

Alkene → Haloalkane reaction name

Electrophilic addition

Alkene → Haloalkane reactants + conditions

HX or X₂

Alkene → Haloalkane mechanism (^& = partial charge)

Curly arrow from C=C bond to ^&+ on H (in H-X) or X (in X-X)

Curly arrow from H—X or X—X to X^&-

Curly arrow from carbocation to X^-

Markownikoff’s rule

If H-X or H₂O are added to an asymmetrical alkene, the major product will have the H added to the carbon from the C=C bond with the most hydrogens already bonded to it

Addition of which compounds does Markownikoff’s rule apply to?

HX or H₂O

Carbocation stability

Increases from primary to tertiary

= More likely to be a major product

Number of R groups in each type of carbocation

primary = 1, secondary = 2, tertiary = 3

Alcohol → Haloalkane reaction name

Nucleophilic substitution

Alcohol → Haloalkane reactants + conditions

NaX, H₂SO_4(aq), reflux

Alkene → Alkane reaction name

Addition

Alkene → Alkane reactants + conditions

H_2(g), 420K, Nickel catalyst

Alkene → Alkane mechanism (^& = partial charge)

Curly arrow from C=C bond to H^&+ in H^&+-H^&-

Curly arrow from H—H bond to H^&-

Curly arrow from H^- to carbocation

Alkene → Alcohol reaction name

Addition

Alkene → Alcohol reactants + conditions

H₂O_(g), concentrated acid catalyst (H₂SO₄/H₃PO₄)

Alkene → Alcohol Mechanism (^& = partial charge)

Curly arrow from C=C bond to H^&+ in H^&+-O^&--H^&+

Curly arrow from ^-:OH to carbocation

Alcohol → Alkene reaction name

Elimination

Alcohol → Alkene reactants + conditions

concentrated acid catalyst (H₂SO₄ or H₃PO₃), reflux

Alcohol → Alkene reaction equation

C_nH_2n+1OH → C_nH_2n + H₂O

Alcohol → Alkene, how are alkenes formed

Removal of hydroxyl group and adjacent H atom (from adjacent C)

Alcohol → Alkene, how many different products

Always water

May create a variety of structural isomers (as H from any adjacent C can be removed so position)

May create stereoisomers (E/Z)

Oxidation of Alcohol possible products (and how)

Aldehydes - primary alcohol, distil

Carboxylic acid - primary alcohol, reflux

Ketones - secondary alcohol, reflux

Alcohol → Aldehyde reactants + conditions

K₂Cr₂O₇/H₂SO₄, distil

Alcohol → Aldehyde reaction equation

Alcohol + [O] → Aldehyde + H₂O

Alcohol → Carboxylic acid reactants + conditions

K₂Cr₂O₇/H₂SO₄, reflux

Alcohol → Carboxylic acid reaction equation

Alcohol + 2[O] → Carboxylic acid + H₂O

Alcohol → Ketone reactants + conditions

K₂Cr₂O₇/H₂SO₄, reflux

Alcohol → Ketone reaction equation

Alcohol + [O] → Ketone + H₂O

Can all alcohols be oxidised

Primary + secondary - yes

Tertiary - no

What reactions do benzene undergo?

Electrophilic substitution

Reactants and conditions for converting benzene to nitrobenzene

Concentrated H₂SO₄ and HNO₃

50°C

Full mechanism for converting benzene to nitrobenzene (or dinitrobenzene)

1. HNO₃ + H₂SO₄ → NO₂⁺ + HSO₄^- + H₂O

2. Arrow from delocalised ring to NO₂⁺. Arrow from C-H bond to partial positive ring. Removal of H⁺.

3. H⁺ + HSO₄^- → H₂SO₄

Reagents and conditions for converting benzene to dinitrobenzene

Concentrated HNO₃ and H₂SO₄

60°C

Reagents and conditions for chlorination/bromination of benzene

Cl₂ and AlCl₃/FeCl₃ catalyst

Br₂ and AlBr₃/FeBr₃ catalyst

Mechanism for chlorination/bromination of benzene (Al_ cat., Cl)

1. Cl₂ + AlCl₃ → Cl⁺ + AlCl₄^-

2. Curly arrow from delocalised ring to Cl⁺. Curly arrow from C-H bond to partial positive ring. Produces H⁺.

3. H⁺ + AlCl₄^- → HCl + AlCl₃

Reagents and conditions for alkylation of benzene

Chloroalkane (R-Cl)

AlCl₃/FeCl₃ catalyst

Mechanism for alkylation of benzene (Al_ cat.)

1. R-Cl + AlCl₃ → R⁺ + AlCl₄^-

2. Curly arrow from delocalised ring to R⁺. Curly arrow from C-H bond to partial positive ring. Produces H⁺.

3. H⁺ + AlCl₄^- → HCl + AlCl₃

Reagents and conditions for acylation of benzene.

Acyl chloride (ROCl)

AlCl₃/FeCl₃ catalyst

Mechanism for acylation of benzene. (Al_ cat.)

1. R-OCl + AlCl₃ → O-R⁺ + AlCl₄^-

2. Curly arrow from delocalised ring to O-R⁺. Curly arrow from C-H bond to partial positive ring. Produces H⁺.

3. H⁺ + AlCl₄^- → HCl + AlCl₃