Reactions Flashcards
Elimination, Organometallic compounds, Substitution
Elimination Reaction
Explain dehydrohalogenation in alkyl halide.
When alkyl halide comtaining **atleast one beta hydrogen **is boiled with alcoholic soln of Potassium Hydroxide, the hydrigen from beta carbon is eliminated along with the halogen group of alpha carbon, forming an alkene.
Preferred product is that alkene which contains most alkyl groups around double bond. (Saytzeff Rule)
Saytzeff rule
Which of the following is most stable?
CH3-CH=CH-CH3 or CH3-CH2-C=CH2
CH3-CH=CH-CH3 is more stable
Organometallic compound
Give example of Wurtz Reaction
2 CH3-CH2-Br + 2Na (IN PRESENCE OF DRY ETHER) =>
CH3-CH2-CH2-CH3 + 2NaBr
Organometallic compound
Explain Wurtz Fittig Reaction
This reaction occurs when alkyl halide and haloarene and sodium are reacted in presence of dry ether to form alkyl derivative of arene.
Organometallic Compound
What type of product is formed in Fittig Reaction?
Biphenyl product is formed in Fittig Reaction
Nucleophillic substitution
Why do aryl halides show low reactivity towards nucleophillic substitution reactions?
Low reactivity of aryl halides is due to -:
- Resonance Effect
- sp2 hybrid state of carbon (C=X)
Substitution
How can one increase the reactivity of haloarene ?
Presence of electron withdrawing group at ortho or para position increases the reactivity of haloarene.
Substitution Reaction
Why does haloarene not show SN1 reaction?
Phenyl cation produced by self ionisation of haloarene will not be stabilised by resonance, hence ruling out SN1 Mechanism.
Substitution Reaction
Why do haloarenes not show SN2 reactions?
Backside attack of nucleophiles is blocked out by aromatic ring, hence SN2 reaction cannot proceed.
Nucleophillic Substitution
Explain formation of Nitro phenol
Chloronitro benzene is heated at 433K with acid and NaOH in order to produce nitrophenol
NO2 is the electron withdrawing grp
Ekectrophillic Substitution
Where is electrophillic group more likely to be attatched during substitution reaction?
Ortho/ para (position containing electron withdrawing grp)
Para position is preffered and setric hindrace is present at ortho group.
What happens when chlorobenzene is treated with chlorine in the presence of anhydrous FeCl2
FeCl2 - Lewis acid
Products include -:
1,4-dichlorobenzene, 1,2-dichlorobenzene and HCl
Predict the major product formed during nitration on chlorobenzene in presence of conc. H2SO4
1-chloro, 4-nitro benzene
What happens when haloarene is heated with H2SO4
Haloarene sulphonic acid is formed along with H2O
Friedel Craft’s Reaction
Explain Friedel Craft’s Alkylation
Conducted by heating haloarene with alkyl chloride in presence of anhydrous aluminium trichloride.
Friedel Craft’s Reaction
Explain Friedel Craft’s Acylation
Conducted by heating haloarene with acyl chloride in presence of anhydrous aluminium trichloride.
