CHEM1112 Lecture Notes - Lecture 4: Phenols, Racemic Mixture, Halocarbon
16 May 2018
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• Identify and name simple alcohols and phenols
• Explain why phenols are more acidic than alcohols
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Alcohols: electronegative OH, polar, H-bonding, high BPs, soluble in water.
Grignard reagents reacted with aldehydes or ketones, intermediate salts hydrolyzed to alcohols.
Nucleophillic Grignard reagent attacks partially positive C of carbonyl group.
Least acidic to most acidic:
Alcohols < water < thiols and Phenols.
In the phenoxide anion, negative charge not localised on the O atom (as it is in hydroxides). Negative
charge is delocalised about the aromatic ring, delocalisation of electrons/charge= greater stability.
• Predict the products of oxidation of an alcohol and give the reagents required to form this
reaction
This is substitution- Nucleophilic- second degree (SN2). Reaction rate proportional to concentrations of
both nucleophile and electrophile. Intermediate: highest energy molecule, where 3 substituents in place
move to trigonal planar arrangement, partial breaking of C-X bond, then full broken C-X and fully formed
C-Nu in the final product.
When reaction rate proportional to concentrations of the organohalide only: Substitution-nucleophilic-
first order (SN1)- 2 step process for tertiary that does’t react through SN reactio. SN: slow step
waits for C-Br to step, unimolecular step to take place, wait for C-X to break from a single molecule,
unlike SN2 reactions that need the molecules to interact for reaction to begin.
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Document Summary
Identify and name simple alcohols and phenols: explain why phenols are more acidic than alcohols. Alcohols: electronegative oh, polar, h-bonding, high bps, soluble in water. Grignard reagents reacted with aldehydes or ketones, intermediate salts hydrolyzed to alcohols. Nucleophillic grignard reagent attacks partially positive c of carbonyl group. In the phenoxide anion, negative charge not localised on the o atom (as it is in hydroxides). Negative charge is delocalised about the aromatic ring, delocalisation of electrons/charge= greater stability: predict the products of oxidation of an alcohol and give the reagents required to form this reaction. Reaction rate proportional to concentrations of both nucleophile and electrophile. Intermediate: highest energy molecule, where 3 substituents in place move to trigonal planar arrangement, partial breaking of c-x bond, then full broken c-x and fully formed. When reaction rate proportional to concentrations of the organohalide only: substitution-nucleophilic- first order (sn1)- 2 step process for tertiary that does(cid:374)"t react through sn(cid:1006) reactio(cid:374).
