1. Organic Reactions
PATHWAYS

2. Reaction pathways
Series of steps to convert one organic compound into a different organic product
Putting together a reaction pathway is a lot like doing a puzzle
Start with given materials  determine final product
Figure out how to use starting materials to create final product
You may find it easier to go backwards!

3. Retrosynthetic analysis
Start by looking at the desired product = target molecule
Look at what is needed to make that target = precursors
Follow a path to what is given in the problem = starting material

4. See page 512
Page 287

5. Produce propyl ethanoate from propene and ethene:
We know we need an ester. What is used to make the ester? Alcohol and carboxylic acid How do we make a carboxylic acid? Oxidation of a primary alcohol How do we make alcohols from alkenes (propene/ethene)? Hydration RXNs (addition) Which one needs to be made into a carboxylic acid? Ethanol

6. Produce propyl ethanoate from propene and ethene
CH3-CH=CH2 + H2O  CH3-CH2-CH2OH (addition reaction)
Propene water propan-1-ol
CH2=CH2 + H2O  CH3-CH2OH (addition reaction)
Ethene water ethanol
CH3-CH2OH [O]  CH3-CHO + [O]  CH3-COOH (oxidation 1º alcohol)
Ethanol (O from K2Cr2O7) ethanal ethanoic acid
CH3-CH2-CH2OH + CH3-COOH  CH3-CH2-CH2-O-CO-CH3 (esterification RXN)
propan-1-ol ethanoic acid propyl ethanoate

7. Summary of Alkane reactions (substitution RXNs)
Alkanes
Convert to halogenoalkanes
Halogenoalkanes
Convert to dihalogenoalkanes
Convert to alcohols

8. Summary of substitution reactions
Alkanes convert to halogenoalkanes or dihalogenoalkanes via a substitution reaction
A Hydrogen in alkane replaced with halogen atom from a halogen molecule
Uses exposure to UV light
Halogenoalkanes convert to alcohols via a nucleophilic substitution reaction
Halogen in the halogenoalkane is replaced with an -OH group via an SN1 or SN2 mechanism

9. Summary of Alkene reactions (Addition RXNs)
Alkenes
Convert to alcohols
Convert to alkanes
Convert to halogenoalkanes
Convert to dihalogenoalkanes
Convert to polyalkene/polymer

10. Summary of Addition reactions
Alkenes convert to alcohols via addition reaction
Water added across double bond in presence of an acid catalyst (like sulfuric acid)
Alkenes convert to alkanes via addition reaction
Hydrogen gas added across double bond in presence of nickel catalyst and heat

11. Summary of Addition reactions
Alkenes convert to halogenoalkanes or dihalogenoalkanes via addition reaction
Hydrogen halide or Halogen added across double bond
At room temperature
Alkenes convert to polyalkene via addition reaction
Repeated units of alkene are added to each other by breaking the double bond

12. Summary of alcohol reactions (oxidation rXNs)
1º alcohols
Convert to aldehydes or to carboxylic acids
2º alcohols
Convert to ketones
Alcohols combined with carboxylic acids
To form esters

13. Summary of alcohol reactions (oxidation rXNs)
1º alcohols convert to aldehydes via oxidation RXN
Acidified potassium dichromate (H+/K2Cr2O7) added to alcohol and heated
As aldehyde produced, removed via distillation 
Aldehydes convert to carboxylic acids via a 2nd oxd.
Aldehydes produced via oxidation of 1º alcohols can be “refluxed” with H+/K2Cr2O7 to yield the carboxylic acid
2º alcohols convert to ketones via an oxidation reaction
H+/K2Cr2O7 added to alcohol and heated

14. Summary of alcohol reactions (Esterification RXNs) ~condensation~
Alcohols combined with carboxylic acids to form esters via a condensation reaction
Water removed in the presence of conc. H2SO4
-OH from carboxylic acid and –H from alcohol
Alcohol becomes prefix of ester name
Carboxylic acid becomes stem of ester name

15. Benzene reactions & Reduction reactions
Convert to substituted benzene
Nitrobenzene
Convert to phenylamine (aniline)
Carbonyl compounds
Convert to alcohols
Reverse of oxidation of alcohols

16. Benzene reactions (substitution of benzene)
Benzene combines with nitronium ion to form nitrobenzene via electrophilic substitution
Conc. H2SO4 catalyst, nitric acid, and 50°C
Produces nitrobenzene and water
Benzene combines with halogens to from halogenobenzene via electrophilic substitution
AlCl3 and dry ether (anhydrous conditions)
Forms halogenobenzene and H-X

17. Reduction reactions Nitrobenzene convert to phenylamine via reduction
Sn, conc. HCl for first step
NaOH for second step
All under reflux conditions (in boiling water bath)
Carbonyl compounds convert to alcohols via reduction
Carboxylic acids/aldehydes convert to primary alcohols
LiAlH4 in dry ether with heat
Ketones convert to secondary alcohols
NaBH4(aq) with heat

18. See page 512
Page 287