AlcoholsR-O-H Classification CH 3, 1 o, 2 o, 3 o Nomenclature: Common names: “alkyl alcohol” IUPAC: parent = longest continuous carbon chain containing the –OH group. alkane drop -e, add –ol prefix locant for –OH (lower number for OH)

CH 3 CH 3 CH 3 CHCH 2 CHCH 3 CH 3 CCH 3 OH OH 4-methyl-2-pentanoltert-butyl alcohol 2-methyl-2-propanol 2 o 3 o CH 3 HO-CHCH 2 CH 3 CH 3 CH 2 CH 2 -OH sec-butyl alcoholn-propyl alcohol 2-butanol 1-propanol 2 o 1 o

Physical properties of alcohols: polar + hydrogen bonding relatively higher mp/bp water insoluble! (except for alcohols of three carbons or less) CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -OH hydrophobic hydrophilic

Oldest known organic synthesis: “fermentation” Sugar + yeast  ethyl alcohol + CO 2 Grape juice => “wine” Barley => “beer” Honey => “mead” Rice => “sake” ~5-11% ethanol

Distillation of fermented beverages to produce “distilled spirits” with a greater percentage of ethyl alcohol (bp 78.3 o C). Ethyl alcohol forms a binary azeotrope with water: 95% ethanol + 5% water (bp o C) Diluted with water => “vodka” 40% ethyl alcohol in water. “proof”: when aqueous alcohol is placed on a sample of gunpowder and ignited, the gunpowder will burn at a minimum concentration of 50% alcohol. This is called “100-proof”. (proof = 2 * alcohol percent)

Add oil of juniper => gin Add peat smoke => scotch Age in a burned barrel => whiskey Add peppermint => schnapps Etc. Ethyl alcohol is a poison. LD 50 = ~10g/Kg orally in mice. Nausea, vomiting, flushing, mental excitement or depression, drowsiness, impaired perception, loss of coordination, stupor, coma, death may occur. (intoxication)

Alcohols, synthesis: Hydrolysis of alkyl halides (CH 3 or 1 o )

NR   some NR  1 o /2 o NR  R-H R-X R-OH Acids Bases Active metals Oxidation Reduction Halogens

Alcohols, reactions: R-|-OH 1.With HX 2.With PX 3 3.(later) RO-|-H 4.As acids 5.Ester formation 6.Oxidation

1. Reaction of alcohols with HX: (#1 synthesis of RX) R-OH + HX  R-X + H 2 O a) HX: HI > HBr > HCl b) ROH: 3 o > 2 o > CH 3 > 1 o c) May be acid catalyzed d) Rearrangements are possible except with most 1 o alcohols.

CH 3 CH 2 CH 2 CH 2 -OH + NaBr, H 2 SO 4, heat  CH 3 CH 2 CH 2 CH 2 -Br n-butyl alcohol n-butyl bromide 1-butanol 1-bromobutane CH 3 CH 3 CH 3 C-OH + HCl  CH 3 C-Cl (room temperature) CH 3 CH 3 tert-butyl alcoholtert-butyl chloride 2-methyl-2-propanol2-chloro-2-methylpropane CH 3 CH 2 -OH + HI, H +, heat  CH 3 CH 2 -I ethyl alcohol ethyl iodide ethanol iodoethane

Mechanism? CH 3 -OH and most 1 o alcohols react with HX via S N 2 mechanism 3 o and 2 o react with HX via S N 1 mechanism  Both mechanisms include an additional, first step, protonation of the alcohol oxygen: R-OH + H +  R-OH 2 + “oxonium ion”

Whenever an oxygen containing compound is placed into an acidic solution, the oxygen will be protonated, forming an oxonium ion.

Mechanism for reaction of an alcohol with HX: CH 3 OH or 1 o alcohols:

Mechanism for reaction of an alcohol with HX: 2 o or 3 o alcohols:

May be catalyzed by acid. S N 2 rate = k [ ROH 2 + ] [ X - ] S N 1 rate = k [ ROH 2 + ] Acid protonates the -OH, converting it into a better leaving group (H 2 O), increasing the concentration of the oxonium ion, and increasing the rate of the reaction.

Rearrangements are possible (except with most 1 o alcohols): CH 3 CH 3 CH 3 CHCHCH 3 + HBr  CH 3 CCH 2 CH 3 OH Br   Br - CH 3 CH 3 [1,2-H] CH 3 CH 3 CHCHCH 3  CH 3 CHCHCH 3  CH 3 CCH 2 CH 3 OH o carbocation 3 o carbocation

Most 1 o ? If large steric requirement… CH 3 CH 3 CH 3 CCH 2 -OH + HBr  CH 3 CCH 2 CH 3 CH 3 Br neopentyl alcohol 2-bromo-2-methylbutane   CH 3 CH 3 CH 3 CH 3 CCH 2 -OH 2 +  CH 3 CCH 2 +  CH 3 CCH 2 CH 3 CH 3 CH o carbocation 3 o carbocation [1,2-CH 3 ]

2.With PX 3 ROH + PX 3  RX a)PX 3 = PCl 3, PBr 3, P + I 2 b)No rearrangements c)ROH: CH 3 > 1 o > 2 o CH 3 CH 3 CH 3 CCH 2 -OH + PBr 3  CH 3 CCH 2 -Br CH 3 CH 3 neopentyl alcohol 2,2-dimethyl-1-bromopropane

3.Dehydration (later)

4)As acids. a)With active metals: ROH + Na  RONa + ½ H 2  b)With bases: ROH + NaOH  NR! CH 4 < NH 3 < ROH < H 2 O < HF

CH 3 CH 2 OH + NaOH  H 2 O + CH 3 CH 2 ONa WA WB SA SB CH 3 CH 2 OH + CH 3 MgBr  CH 4 + MgBr(OCH 2 CH 3 ) SA SB WA WB CH 3 OH + NaNH 2  NH 3 + CH 3 ONa SA SB WA WB

5.Ester formation. CH 3 CH 2 -OH + CH 3 CO 2 H, H +  CH 3 CO 2 CH 2 CH 3 + H 2 O CH 3 CH 2 -OH + CH 3 COCl  CH 3 CO 2 CH 2 CH 3 + HCl CH 3 -OH + CH 3 SO 2 Cl  CH 3 SO 3 CH 3 + HCl Esters are alkyl “salts” of acids.

oxidation states of carbon - oxidation  CH 4 CH 3 OH CH 2 O HCO 2 H CO  reduction -

6.Oxidation Oxidizing agents: KMnO 4, K 2 Cr 2 O 7, CrO 3, NaOCl, etc. Primary alcohols: CH 3 CH 2 CH 2 -OH + KMnO 4, etc.  CH 3 CH 2 CO 2 H carboxylic acid Secondary alcohols: OH O CH 3 CH 2 CHCH 3 + K 2 Cr 2 O 7, etc.  CH 3 CH 2 CCH 3 ketone Teriary alcohols: no reaction.

Primary alcohols can also be oxidized to aldehydes: CH 3 CH 2 CH 2 -OH + C 5 H 5 NHCrO 3 Cl  CH 3 CH 2 CHO pyridinium chlorochromate aldehyde or CH 3 CH 2 CH 2 -OH + K 2 Cr 2 O 7, special conditions 

Alcohols, synthesis: Hydrolysis of alkyl halides (CH 3 or 1 o )

Alcohols, reactions: R-|-OH 1.With HX 2.With PX 3 3.(later) RO-|-H 4.As acids 5.Ester formation 6.Oxidation