Alcohol

Things that will be discussed:

• Introduction
• Nomenclature and naming
• Properties
• Applications
• Production
• Reactions
• Effects

Introduction

• al·co·hol
• chemist term - any organic compound whose molecule contains one or more hydroxyl groups attached to a carbon atom.
• human term - a colorless volatile flammable liquid that is the intoxicating constituent of wine, beer, spirits, and other drinks, and is also used as an industrial solvent and as fuel

Untitled Slide

nomenclature and naming

• The suffix -ol appears in the IUPAC chemical name
• where the hydroxyl group is the functional group with the highest priority
• the simplest members is the saturated straight chain alcohols
• the general formula : C(n)H(2n+1)OH.

Ball-and-stick model of the hydroxyl
(-OH) functional group in an alcohol molecule (R3COH). The three "R's" stand for carbon substituents or hydrogen atoms.

Untitled Slide

Untitled Slide

Eg. 2-methyl-2-butanol

Alcohol?

physical properties

• odours of biting or stingy sometimes hanging in nasal passage
• Ethanol has a slightly sweeter odour comparably to other alcohol

chemical properties

• hydroxyl group makes the alcohol molecule polar
• the tendency of the polar OH to promote solubility in water
• the tendency of the carbon chain to resist it
• can show either acidic or basic properties at the -OH group
• alcohols tend to have higher boiling points than comparable hydrocarbons and ethers
• Alcohols can also undergo oxidation to give aldehydes, ketones, or carboxylic acids, or they can be dehydrated to alkenes
• the hydrogen bond strength, boiling point, and the acidity typically decrease (1-3)
• hydrogen bonding

APPLICATIONS

• Alcoholic beverages
• Anti-freeze
• Antiseptics
• Fuels
• Preservatives
• Solvents

Production

• Ziegler and oxo process
• Hydration reactions
• Biological routes
• Laboratory substitution
• Laboratory reduction
• Laboratory hydrolysis

Ziegler and oxo process

Untitled Slide

• Process of synthesising 1-octanol with ethylene and triethylaluminium
• Involves oxidation and hydrolysis
• Generates range of alcohol separated by distillation
• Higher alcohols by hydroformylation > hydrogenation

Hydration reactions

Untitled Slide

• Addition of water to alkenes
• Direct method : using acid catalysts, avoid stable intermediates/using ethylene
• Indirect method : alkene>sulfate ester(hydrolysed)
• Produce the diol ethylene glycol from ethylene oxide

Biological routes

Untitled Slide

• Presence of yeast and temperature of 37°C
• Ethanol is obtained by fermentation of glucose from sugar through hydrolysis of starch
• sucrose→glucose + fructose (by invertase)
• glucose→ethanol + CO2 (by zymase)

Reactions

• Deprotonation
• Nucleophilic substitution
• Dehydration
• Esterification
• Oxidation

Deprotonation

Untitled Slide

• Alcohols can behave as weak acids
• produce an alkoxide salt
• performed either with a strong base such as sodium hydride or n-butyllithium or with sodium or potassium metal

Nucleophilic substitution

Untitled Slide

• oxygen is first protonated to give R−OH2+
• leaving group (water) is much more stable
• nucleophilic substitution can take place

Dehydration

Untitled Slide

• produce ethers and water
• Tertiary alcohols eliminate easily at just above room temperature, but primary alcohols require a higher temperature.
• http://en.wikipedia.org/wiki/File:DehydrationOfAlcoholWithH-.png

Esterification

Untitled Slide

• performed at reflux with a catalyst of concentrated sulfuric acid
• R-OH + R'-COOH → R'-COOR + H2O
• water is usually removed
• reaction of the alcohol with an acid chloride

Oxidation

Untitled Slide

• 1st =oxidized either to aldehydes (R-CHO) or to carboxylic acids (R-CO2H)
• 2nd = terminates at the ketone (R1R2C=O)
• 3rd = resistant to oxidation

Effects

ouy knaht