Alcohol, Phenol, and Ether

What are Alcohol Phenols and Ethers?

The terms Alcohols Phenols and Ethers belong to the class of organic compounds. These compounds have a huge application count in industries for domestic purposes. When the hydroxyl (-OH) group bonds with the saturated carbon atom, we receive Alcohol. And the dehydration of alcohol forms Ether. Based on the hydroxyl group, there are three types of alcohol named Monohydric, Dihydric, and Trihydric.

These compounds are the organic compound classes that find diverse usage in a wide range of industries and for domestic purposes.

  • Alcohol is formed while the saturated carbon atom is bonded to a hydroxyl (-OH) group.

  • Phenol is formed when the hydrogen atom present in a benzene molecule gets replaced by the -OH group.

  • The ethers are formed when an oxygen atom is connected to either two aryl or alkyl groups.

Let us look at more detail about the types of alcohol, ether, and phenol, including their classification, with a few examples:

 

Classification of Alcohol

Based on the number of attached hydroxyl groups, alcohol can be classified into three types, as listed below:

  • Monohydric alcohols: These contain one -OH group. An example is CH3CH2-OH.

  • Dihydric alcohols: These contain two -OH groups. An example is 1,2-Ethanediol.

  • Trihydric alcohols: These contain three -OH groups. An example is 1,2,3-Propantriol.

Based on the number of carbon atoms that are attached to the carbon that is bonded directly with the -OH group, alcohols are classified into three types.

  • Primary alcohols - Here, one carbon atom is attached directly.

  • Secondary alcohols - Here, two carbon atoms are attached directly.

  • Tertiary alcohols - Here, three carbon atoms are attached directly.

Classification of Phenol

Based on the number of hydroxyl groups count attached, phenols are classified into three types, as listed below:

  • Monohydric phenols - These contain one -OH group.

  • Dihydric phenols - These contain two -OH groups, maybe “ortho-,” “meta-” or “para-” derivatives.

  • Trihydric phenols - These contain three -OH groups.

Classification of Ether

Based on the aryl or alkyl groups type attached to the oxygen atom in ether, we can classify it into two types.

  • Symmetrical Ether - It is also called the simple ether; the aryl or the alkyl group that is attached to either side of the oxygen atoms are similar. Examples can be given as C2H5OC2H5, CH3OCH3, and more.

  • Unsymmetrical Ether - Unsymmetrical ether - We can also refer this to as mixed either, which is the aryl or the alkyl group, attached to either side of the oxygen atoms and are not similar. Examples can be given as C2H5OC6H5, CH3OC2H5, and more.

Nomenclature of Alcohols, Phenols, and Ethers

  1. Nomenclature of Alcohols

Alcohols are three major classes which are listed below.

  • Monohydric Alcohol

  • Dihydric Alcohol

  • Trihydric Alcohol

Let us now discuss the nomenclature of these alcohols.

  • Monohydric Alcohol

Monohydric alcohols are given with the general formula CnH2(n+1)OH, where n = 1, 2, and so on. Also, we can represent them as R-OH, where R denotes an alkyl group.

Common System

In the common system, we can name monohydric alcohols as Alkyl Alcohol. We can get their names by adding the name alcohol after the alkyl group name is present in the molecule. For example, the CH3-OH compound has one methyl group with an alcohol group. Therefore, we call it Methyl Alcohol.

  • Dihydric Alcohol

Dihydric alcohols are given with the general formula, (CH2)n(OH)2, where n= 2,3,4, and so on. Due to their sweet taste, we refer to them as Glycols. Based on the two hydroxyl group's relative position, we can classify these as α, β, ϒ, ….., ω-glycols, and more. Let us look at their nomenclature system.

Common System

In the common system, we name the α- glycols simply by adding the word Glycol after the end of the alkene name. In contrast, the β, ϒ … ω – glycols get their names the same as the corresponding polyethylene glycols. For example,

  • Trihydric Alcohol

The formula of trihydric alcohols can be given as(CH2)n(OH)3 where n = 3, 4, 5, ….., and so on. We do not have any general nomenclature rules in this system. So, there is only the IUPAC rule. In the trihydric alcohol IUPAC system, we call them Alkanethiols and use Arabic numerals to indicate the OH group position.

  1. Nomenclature of Phenols

Phenol is the simplest derivative of benzene. It is also the common name and an accepted IUPAC name as well. We can name the substituted phenols as the derivatives of phenols both in IUPAC and the common system.

In this common system, we can indicate the substituent position that is on the benzene ring with respect to the –OH group, by adding the prefix like meta (m-) for 1,3, ortho (o-) for 1:2, and para (p-) for 1,4.

Nomenclature of Ethers

Common System

We can get the common names of ethers simply by naming the two aryl or alkyl groups linked to oxygen atoms as separate words in alphabetical order and adding ether at the end. In the case of symmetrical ethers, we use the “di” prefix before the alkyl or the aryl group name.

Tests to distinguish between Phenol, Alcohol, and Ether

To differentiate and identify if the given compound is an alcohol, phenol, or ether, the following tests can be employed:

(i) To differentiate between alcohols and phenols:

Sr No.

Chemical test

Alcohols

Phenols

1.

Litmus test

No effect

Turns blue litmus red

2.

Ferric chloride test

No colour change

Produce blue, violet or green colouration

3.

Bromine water test

No precipitation reaction

Produce white precipitates

4. 

Reaction with sodium hydroxide (NaOH)

No reaction

Reacts with NaOH to form phenoxides

5.

Iodoform test

Gives positive test with the formation of yellow precipitates.

No reaction occurs.

 

(ii) To differentiate between phenols and ethers:

Sr No.

Physical/ Chemical test

Phenol

Ether

1.

Neutral Ferric chloride test

Blue/ Violet/ Green colour observed

No colour change observed

2.

Boiling point

Have a high boiling point due to aromatisation.

Have a low boiling point.

 

(iii) To differentiate between Alcohol and ether:

Sr No.

Physical/ Chemical test

Alcohol 

Ether

1.

Lucas test (anhydrous zinc chloride in conc. HCl)

Gives a positive test with the formation of a cloudy solution. Tertiary alcohols give the fastest result followed by secondary and primary alcohols. In primary alcohols generally, cloudy changes in solution are not observed.

No change observed

2.

Boiling point

Have a high boiling point

Have a low boiling point

3. 

Halogenation reaction

No reaction

Form halogenated ethers with chlorine and bromine in the dark

4. 

Esterification reaction

Fruity smell develops due to the formation of esters

No change in the solution

5.

Sodium metal reaction

Reacts with active sodium metal to form a compound called sodium alkoxide along with brisk effervescence due to the release of hydrogen gas. The solution remains colourless.

No reaction is observed.

In this way, alcohols, phenols, and ethers compounds can be distinguished. There are several other methods too, for example, different physical properties such as density, specific gravity, flashpoints, etc.

To know more about alcohol, phenol, and ether, log on to Vedantu and find deeper insights from the expert teachers. Clarify all your doubts from the top mentors at live sessions.

FAQs (Frequently Asked Questions)

1. Explain the IUPAC Nomenclature of Phenols and Ethers?

Phenols

Coming to the IUPAC system, we can use Arabic numerals to indicate the position of the substituent with respect to the –OH group. The carbon that carries the OH group gets the number 1. The phenols that are having a carbonyl group like ketonic, aldehyde, carboxyl, or an ester group will get their names as the hydroxyl derivatives of the parent aromatic compounds.


Ethers

In the IUPAC nomenclature system, ethers are called Alkoxy Alkanes. The ethereal oxygen is further taken with the smaller alkyl group and produces a part of an alkoxy group. On the other side, the larger alkyl group is taken to be a part of the alkane.

2.  Why Do the Ethers Have a Dipole Nature? Does the dipole moment get cancelled?

One of the physical properties of ether is its dipolar nature. This is due to the polar nature of the C-O bond producing a net dipole moment. However, the polarity strength is weak and does not considerably change the physical properties of ether.  Ethers, therefore, have the same boiling points as alkanes. Even when the ether compound appears to be symmetrical due to the alkyl group on both sides of the oxygen atom, they are in fact not symmetrical. This creates a bent geometry of the compound. Hence the dipole moment does not get cancelled.

3. What are the various uses of alcohol, ether, and phenolic compounds?

Compounds of alcohol, ether, and phenols are the basic constituents of many day-to-day industrially useful materials. They are variously used in the production of detergents, soaps, and antiseptics. The phenolic group present in Vitamin E is crucial for the compound's antioxidant activity. All sugars and carbohydrates are polyhydroxy alcohols and these compounds are a vital source and medium of stored energy form. Diethyl ether was previously used as an anaesthetic in the field of medicine. Cyclic ethers (also known as epoxides) are important hormonal compounds in some insects.

4. What is the general formula of Ether? Describe the classification of ethers in brief?

The general formula of ether is R-O-R’ where o denotes oxygen atom and R and R’ denote the attached alkyl or aryl group. Ether compounds can be classified in various ways. For example, ethers can be categorised into symmetrical or simple ethers and asymmetrical or mixed ethers based on if the alkyl groups are attached to the same side or different sides of the oxygen atom.

5. How can phenols be distinguished from an alcoholic compound such as methyl alcohol?

Phenolic compounds can be differentiated from alcoholic compounds through the use of various chemical tests such as:

  • Litmus test: With the help of litmus, phenols can be distinguished from alcohols as phenols clearly turn blue litmus red while alcohols show no effect on litmus paper.

  • Bromine water test: Phenols react with bromine water to produce white precipitates while alcohol does not undergo precipitation reaction.

  • Ferric Chloride test: Phenols undergo a chemical reaction with ferric chloride solution to produce blue, green, or violet colour while no colour change is observed when alcohols react with it.

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