1 Dr Nahed Elsayed

Learning Objectives Chapter six concerns alcohols and phenols and by the end of this chapter the student will:  know the difference in structure between alcohols and phenols  Know the different classes of alcohols  Know how to name alcohols and phenols  Know the physical properties (solubility, boiling and melting points)  Know how hydrogen bonds are formed and its effect on boiling points of alcohols  Know the acidic properties of alcohols and phenols  know the different methods that can be used to prepare alcohols and phenols.  Know the chemical reactions of these compounds ( some reactions are review, others are extensions of the chemistry that will be discussed on chapters 8, 9 & Chem.

3 King Saud University Chemistry Department  Alcohols and phenols may be viewed as organic derivatives of water.  Alcohols and phenols have a common functional group, the hydroxyl group, —OH. - In alcohols the hydroxyl group is attached to an alkyl group, —R. - In phenols the hydroxyl function is directly attached to benzene ring H-O-H R-O-H or PhCH 2 OH Ph-O-H Water Alcohol Phenol Structure Of Alcohols and Phenols

according to the type of the carbon atom connected to the hydroxyl group (carbinol carbon) Alcohols are classified according to the type of the carbon atom connected to the hydroxyl group (carbinol carbon) into: 4 King Saud University Chemistry Department Classification and Nomenclature of Alcohols 145 Chem.

1.Select the longest continuous carbon chain that contains the -OH group. Replace the ending e of the alkane by the suffix –ol 2. If a molecule contains both an -OH group and a C=C or cΞc bond;  Choose the chain that include both of them even if this is not the longest chain.  The name should include suffixes indicate presence of both the OH group and the unsaturated groups.  The OH group takes precedence over the double or triple bonds in getting the lower number.  Cyclic alcohols are named using the prefix cyclo-, the carbon bearing the hydroxyl group is assumed to take number The suffix diol or triol is added to the name of the parent hydrocarbon when there are two OH or three OH groups respectively. 145 Chem. 5 King Saud University Chemistry Department NOMENCLATURE OF ALCOHOLS IUPAC Nomenclature Of Alcohols Alcohols are named according to the following rules:

6 Common Nomenclature Of Alcohols  List the names of alkyl substituents attached to the hydroxyl group, followed by the word alcohol.  If two OH groups present on two adjacent carbons these known as glycols King Saud University Chemistry Department Primary alcohols CH 3 OHCH 3 CH 2 OH CH 2 =CHCH 2 OH CommonMethyl alcoholEthyl alcohol Allyl alcohol IUPACMethanolEthanol 2-Propen-1-ol 145 Chem.

7 Secondary and tertiary alcohols CommonIsopropyl alcoholCyclopentyl alcoholMethylcyclohexyl alcohol IUPAC2-PropanolCyclopentanol 1-Methyl-1-cyclohexanol King Saud University Chemistry Department 145 Chem.

8 4-Methyl-2-cyclohexen-1-ol 1-Phenylmethanol Benzyl alcohol (common name) 2-Phenylethanol Ethan-1,2-diol Ethylene glycol (common name) King Saud University Chemistry Department Examples Examples 145 Chem.

Examples Examples King Saud University Chemistry Department 145 Chem.

10  Alcohol and water contain hydroxyl group that can form hydrogen bonds.  The hydroxyl group is hydrophilic “water loving”  The alkyl group of alcohols is hydrophobic “ water hating”  As the number of the –OH group in alcohol increases, the solubility in water increases.  The lower alcohols are completely miscible with water  Diols and triols are more soluble in water than monohydroxyalcohols.  As the number of carbons in the alcohol increases, the solubility in water decreases. King Saud University Chemistry Department Physical Properties of Alcohols 1) Solubility Of Alcohols and Phenols

145 Chem. 11 King Saud University Chemistry Department Physical Properties of Alcohols 2) Boiling Points of Alcohols  The boiling points increase with increase in molecular weights.  Alcohols have higher boiling points(b.p.) than alkanes of similar weight this is due to the presence of hydrogen bonds between molecules of alcohols. hydrogen bond

12 King Saud University Chemistry Department 3)Acidic Properties of Alcohols  Alcohols are very weak acids  The hydroxyl proton of an alcohol is weakly acidic  A strong base can abstract the hydroxyl proton to give an alkoxide ion  Electron-withdrawing group (-I) increase acidity  Electron-releasing group (+I) decrease acidity 145 Chem.

13 King Saud University Chemistry Department Synthesis (Preparation) of Alcohols 1- From Alkenes (Hydration and oxidation of alkenes) 2- From alkyl halide by nucleophilic substitution (N.B. elimination of HX using base gives alkene (N.B. elimination of HX using base gives alkene i) Hydration of alkenes ii) Oxidation of alkenes

145 Chem. 14 King Saud University Chemistry Department 3- Reduction of aldehydes, ketones and carboxylic acids

145 Chem. 15 King Saud University Chemistry Department 4- Addition of Grignard compounds to aldehydes & ketones Tertiary alcohol Ketone Secondary alcohol Primary alcohol Methanal formaldehyde

A. Formation of Salt 145 Chem Dissociation of O-H Bond Sodium ethoxide King Saud University Chemistry Department Reaction of Alcohols B. Formation of Esters H+H+ H + / H 2 O

A. Elimination Reactions 145 Chem. 17 King Saud University Chemistry Department B. Substitution Reaction 2. Dissociation of C-O Bond i.e. cleavage of C ــــOH bond

145 Chem 18 King Saud University Chemistry Department C. Oxidation Reactions

145 Chem.19 Phenols (compounds having hydroxyl group directly attached to a benzene ring ) are generally named as derivatives of the simplest member of the family, phenol Acidity :  Alcohols and phenols have weak acidic properties.  Phenols are much stronger acids than alcohols.  Introduction of electron-withdrawing groups, such as NO 2 or CN, on the ring increases the acidity of phenols. Nomenclature and acidity of Phenols King Saud University Chemistry Department

20 King Saud University Chemistry Department

145 Chem. 21 Synthesis of Phenols King Saud University Chemistry Department

145 Chem. 22 Reactions Phenols King Saud University Chemistry Department Ethers formation

145 Chem. 23 King Saud University Chemistry Department 2. Electrophilic Substitution Reactions

145 Chem. 24 Home Work King Saud University Chemistry Department

4) The IUPAC name of is: A) 4-Ethyl-5-heptyn-3-ol B) 4-Ethyl-5-heptan-3-ol C) 4-Ethyl-5-hepten-3-ol D) 4-Etyl-2-hepten-5-ol 5) The IUPAC name of is: A) 3-Methyl-1-bromocyclohexanol B) 2-Bromo-3-methylcyclohexanol C) 4-Bromo-2-methylcyclohexanol D) 3-Bromo-1-methylcyclohxanol 145 Chem. 25 King Saud University Chemistry Department 6) The most acidic compound is

7) The common name of 2-methyl-2-propanol is: A) Allyl alcohol B) Isopropyl alcohol C) tert-Butyl alcohol D) Benzyl alcohol 8) The following reaction gives A) 4-Ethylphenol B) 2-Ethylphenol C) Ethylphenyl ether D) Ethylphenyl ketone 145 Chem. 26 King Saud University Chemistry Department

27 10) The product of the reaction shown below is 11) Which of the following compounds has the highest boiling point? 9) The major product for the following reaction is

Questions?