12th Class Chemistry Chapter 11 Alcohols Phenols and Ethers Short Questions Answer

The process of conversion of starch and sugar to ethyl alcohol under the influence of yeast is called fermentation.There should be proper aeration solution should be dilute and there should be no preservative for fermentation purposes.

Ethyl alcohol can be prepared by the fermentation of cane juice beets dates molasses and fruit juices.These substances have fermentable sugars. Moreover ,Potatoes,rice,barley and maize contain starch which give us alcohol on fermentation.

Absolute alcohol cannot be prepared by fermentation process.Actually 14% alcohol is obtained in fermentation process which can be concentrated upto 95%.95% alcohol forms azeotropic mixture which cannot be futher concentrated by distillation.Anyhow lime is used to concentrate alcohol further.

95% ethyl alcohol is called rectified spirit.It is also called commercial alcohol.It is converted to 99.9% alcohol by distilling it in the presence of CaO.This is called absolute alcohol.

Alcohol is denatured by the addition of 10% methanol.In this way it becomes poisonous and becomes unfit for drinking purpose.This is called methylated spirit.A small quantity of pyridine or acetone may be added for denaturing.

Ethanol has a hydrogen bonding among the molecues.For this reason it has a higher boiling point than that of ether.Ether is a non-polar molecule and there is no hydrogen bonding in it.The extent of H-bonding in H2O is much greater than alcohol.

Water has two partial positive hydrogen atoms and alcohol have one.So there is hydrogen bonding in them which makes them miscible.

The reaction of carboxylic acids with alcohols in the presence of an acid as a catalyst give us esters and water.This is a reversible reaction and is called esterification.

When primary and secondary alcohols are heated at 300ᵒCin the presence of copper primary alcohols are converted into aldehydes secondary alcohols into ketones and tertiary alcohols into alkenes.

When primary secondary  and  tertiary alcohols are treated with HCI in the presence of ZnCI₂  tertiary alcohols give the oily liquids immediately.Secondary alcohols give  the reaction within 5-10 minutes and primary alcohols do not give the  reaction at room temperatre.

All those  primary or secondary alcohols which on oxidation give  methyl aldehde or methyl ketones give the haloform reaction,e.g.C₂H₅ – OH-,CH₃-CH-CH₃etc.give the haloform reaction.CH₃CH₂OH gives  CH₃CHO and CH₃CH(OH)CH₃ gives  CH₃COCH₃ which  further react to produce CHI₃.

Ethyl alcohol upon ocidation give CH₃CHO.It is an aldehyde having- CH₃ with – C = O group  and can give the iodoform reaction.Methyl alcohols give formaldehyde.It does not have CH₃ group.So it will not give haloform reaction.

Methyl alcohol is used as a solvent for oils fats paints and varnishes.It is anitifreeze for automobile radiators.It is used for the denaturing of alcohols.It is used for the manufacture of formaldehyde drugs and perfumes.

It is used as a solvent for paints drugs oils perfumes dyes varnishes,medicines and gums.It is used for the preservations of biological specimens and as an antifreeze for automobile radiators.It is useed as a petrol substitute and as a fuel in spirit lamps and stoves.

It is colorless hygroscopic crystaline solid melts at 4ᵒC adn boils at 182ᵒC.It is partially miscible with water and readily soluble in alcohol.It is poisonous substance and produces  painful blisters in contact with the skin.

When phenol gives the protons phenoxide ion which is produced develops the five resonance structures and attains the stability.It favours the reaction to the forward direction adn makes the phenol to release the proton.

When bromine water reacts with phenol tribromophenol is produced which settles down in the form of white ppt.So phenol can be distinguished from other substances b this reaction.

          – OH group is o-,p-directing with activation.

When phenol is reacted  with  methanal solution ortho and para positions of phenols are occupied by – CH₂– OH group.These  compounds condense with each other to give a polymer called bakelite.The joining of molecule eliminates H₂O.

Phenol is used to produce bakelite drugs phenolphthalene and explosives .It is used as a wood preserative in gervicides and in antiseptic.

NaOH and FeCI₃ react with phenol but not with  alcohol.Phenol does not react with carboxylic  acids and halogen acids but alcohols do.Phenols react with diazonium salts to give dyes but alcohols do not  give this reaction.

Ether is used as a general anaesthetic  and as  refrigerant.It can  act as a solvent for the extraction of organic compounds and can  dissolve  fats oils and resins.IT si a substitute of petrol by mixing with  alcohol.It is used as a perfumery adn the manufacture of smokeless gun powder.

Those ethers in which  two alkyl or aryl groups attached with oxygen  atom are not alike are called  mixed ehters.
CH₃ – o –C₂H₅………………… Ethyl methyl ether .
C₂H₅ – O-C₃H₇…………………. Ethyl propyl ether.
CH₃ – O – C₆H₅…………………. Methyl phenyl ether.

Ethers adn alcohols are alkyl derivatives of water.Ethers have least hydrogen bonding and little tendency break C- O bond as compared to alcohols and water  which have  O-H  bonds in them.Actually alkyl groups are dominants  and they show their properties.

Ethers and alcohols are alkyl derivatives of water.Ethers have least hydrogen  bonding and little tendency break C-O bond as compared to alcohol and water which  have O – H  bonds in them.