Class 11 Engineering Chemistry - Organic Chemistry - Some Basic Principles And Techniques

What would be the product of
$NaOH$ + $SiO_2$ $\rightarrow$ ?

1397400_1237537_ans_4d536eb31ba1416fa951bd61d010b5a8.jpg

Identify $A, B, C$ and $D$ .

1443347_878352_ans_808102e834104f4d8ac1c9d627f2d7af.png

How many (x) moles of HI consumed?

2

$2$ moles of

H I

$HI$ are consumed in the reaction.Ether bond between two phenol rings is not cleaved as it not give stable carbocation.
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Match the column.
Column (I) - $E_2$ reaction (elimination biomolecular)
Column (II) - No. of possible products. (including stereoisomerism)

Refer to image 01

Refer to image 02

Dehydrohalogenation is not possible because

3^{o}

$3^o$ carbon is present here which can't undergo any further reaction.

1120073_991877_ans_4dee454174024d11916563e317433fb4.png

What is the product formed?

The reaction mechanism is

S N^{1}

$SN^1$ and

C^{+}

$C^+$ is formed where it is most stable [

C^{+}

$C^+$ is carbocation].
1174260_1070502_ans_844919ca85854d69942ecc7a5dd35007.PNG

Find the product of the given reaction.

N a B H_{4}

$NaBH_4$ can reduce aldehydes,ketones to alcohols but generally do not reduce esters,carboxylic acids or amides.
1170483_1073438_ans_e7051f5f3ddd408194d7c1ea4855c821.png

1170483_1073438_ans_e7051f5f3ddd408194d7c1ea4855c821.png

Provide a detailed reaction mechanism for the following.

1657776_1718955_ans_70d982045cfc4bb3bb0c9ed60e8bbb89.jpg

Fill in the following blanks with suitable words:
The next higher homologue of ethanol is ________.

Next homologue is differ by

- C H_{2}

$-CH_2$ unit.

Ethanol

C H_{3} - C H_{2} - O H

$CH_3-CH_2-OH$

So next homologue will be

C H_{3} - C H_{2} - C H_{2} - O H

$CH_3-CH_2-CH_2-OH$ Propanol.

The next higher homologue of ethane is _______.

The members of the homologous series differ by the unit

- C H_{2}

$-CH_2$ .

If we have to find out the next homologue of ethane or

C H_{3} - C H_{3}

$CH_3-CH_3$ , we have to add the unit

- C H_{2}

$-CH_2$ to it.

In this way, the next homologue comes out to be

C H_{3} - C H_{2} - C H_{3}

$CH_3-CH_2-CH_3$ or propane.

Fill in the following blanks with suitable words:
The next homologue of $C_{2}H_{5}OH$ is _______

Next homologue is differ by

- C H_{2}

$-CH_2$ unit. Ethanol is

C H_{3} - C H_{2} - O H

$CH_3-CH_2-OH$

So next homologue will be

C H_{3} - C H_{2} - C H_{2} - O H

$CH_3-CH_2-CH_2-OH$ Propanol i.e.

C_{3} H_{7} O H

$C_{3}H_{7}OH$ .

Identify the unknown organic compounds $(D)$ to $(E)$ in the following series of chemical reactions.
$(D)\xrightarrow [ \Delta ]{ H_{2}/Ni } (E)$

1650018_1780728_ans_bc6776580a504536a3022554e7e58b01.png

Write the next homologue of each of the following:
(i) $C_{2}H_{4}$
(ii) $C_{4}H_{6}$

The next homologues of the given compound are:

(i)

C_{3} H_{6}

$C_{3}H_{6}$
(ii)

C_{5} H_{8}

$C_{5}H_{8}$

What is the next homologue of $C_{3}H_{7}OH$ called?

The next homologue of

C_{3} H_{7} O H

$C_{3}H_{7}OH$ is called butanol (

C_{4} H_{9} O H

$C_{4}H_{9}OH$ ).

Which two of the following organic compounds belong to the same homologous series?
$C_{2}H_{6},C_{2}H_{6}O,C_{2}H_{4}O_{2},CH_{4}O$

C H_{4} O

$CH_{4}O$ and

C_{2} H_{6} O

$C_{2}H_{6}O$ belong to the same homologous series that has a general formula

C_{n} H_{2 n + 2} O

$C_nH_{2n+2}O$ .

Both have alcohol as a functional group,

C H_{3} - O H

$CH_3-OH$ and

C H_{3} - C H_{2} - O H

$CH_3-CH_2-OH$ belonging to the same homologous series.

Whereas,

C H_{3} - C H_{3}

$CH_3-CH_3$ is an alkane and

C H_{3} - C O O H

$CH_3-COOH$ is an acid.

Fill in the blanks:
Propane and ethane are ________

A succeeding members of a homologous series differ by

C H_{2}

$CH_2$ unit

C H_{3} - C H_{3}

$CH_3-CH_3$ - Ethane

C H_{3} - C H_{2} - C H_{3}

$CH_3-CH_2-CH_3$ - Propane

Propane and ethane are homologues.

The molecules of alkene family are represented by a general formula $C_nH_{2n}$ . Answer the following:
Write the molecular formula of lower and higher homologous of an alkene which contains four carbon atoms.

Lower homologus of alkene which contains four carbons is

C_{3} H_{6}

$C_3H_6$ .

Higher homologus of alkene which contain four carbons is

C_{5} H_{10}

$C_5H_{10}$ .

The molecular formula of the first member of a certain group of organic compound is $CH_{2}O$ . Determine the name and molecular formula of the third member of this group if the member of this group are in series what is the general name of this group of organic compounds?

The molecular formula of the first member of a certain group of organic compound is

C H_{2} O

$CH_{2}O$ . The name and the molecular formula of the third member of this group is propanol and its molecular formula is

C_{3} H_{6} O

$C_{3}H_{6}O$ . The members of this group are in homologous series. The general name for this group is called aldehydes.

Find the final product.

Ring is more Activated towards electrophilic substitution reaction due to the presence of

- N H C O R

$-NHCOR$ group which

- I

$-I$ and

+ M

$+M$ effect.
1380682_878315_ans_ea25dffdb55a47478601c048c21034bb.png

The product is?

Alkyl ethers are cleaved by the strong acids

H I

$HI$ or

H B r

$HBr$ in a nucleophilic substitution reaction similar to that of alcohols.

$R-O-R^{'}\,\,+HI\rightarrow R-I\,\,+R^{'}-OH$

Mechanism:-

1) Protonation of the alcoholic oxygen.

$I^{-}$ ion acts as the nucleophilic & attacks to displace the good leaving group, alcohol molecule by cleaving the

$C-O$ bond.

The given figure represents the reaction.

1094014_1181833_ans_526799641e6e4a4694dd75261a0d0277.png

$\text{Complete the following table:}$
$\text{Name}$ $\text{Molecular formula}$ $\text{Condensed structural formula }$ $\text{Number of carbon atoms }$ $Number \ of -CH_{2}-units$
Methane $CH_{4}$ $CH_{4}$ 1 1
Ethane $C_{2}H_{6}$ $CH_{3}-CH_{3}$ 2 2
Propane $C_{3}H_{8}$ $CH_{3}-CH_{2}-CH_{3}$ 3 3
Butane $C_{4}H_{10}$ $CH_{3}-CH_{2}-CH_{2}-CH_{3}$
Pentane $C_{5}H_{12}$ $CH_{3}-CH_{2}-CH_{2}-CH_{2}-CH_{3}$
Hexane $C_{6}H_{14}$ $CH_{3}-CH_{2}-CH_{2}-CH_{2}-CH_{2}-CH_{3}$

$\text{Name}$

$\text{Molecular formula}$

$\text{Condensed structural formula }$

$\text{Number of carbon atoms }$

$Number \ of -CH_{2}-units$

Methane

$CH_{4}$

Ethane

$C_{2}H_{6}$

$CH_{3}-CH_{3}$

Propane

$C_{3}H_{8}$

$CH_{3}-CH_{2}-CH_{3}$

Butane

$C_{4}H_{10}$

$CH_{3}-CH_{2}-CH_{2}-CH_{3}$

Pentane

$C_{5}H_{12}$

$CH_{3}-CH_{2}-CH_{2}-CH_{2}-CH_{3}$

Hexane

$C_{6}H_{14}$

$CH_{3}-CH_{2}-CH_{2}-CH_{2}-CH_{2}-CH_{3}$

Write the name and formula of the 2nd member of homologous series having general formula ${C_n}{H_{2n}}$ .

2nd member means

$n=2$

Putting the value of n in the formula

$C_nH_{2n}$

We get formula as

$C_2H_2$

And name is ethene.

In homologous series of aldehyde, the consecutive members of the series differ by the mass of:

A homologous series may be defined as a group of a class of compounds, each member of which differs from the preceding or succeeding member by one

$CH_2$ . The members of the series are known as homologs.
Ethanal

$(CH_3CHO)$ and propanal

$(CH_3CH_2CHO)$ are two consecutive members of the homologous series of aldehydes. In these compounds, the physical properties such as melting point, boiling point, density, etc., gradually increase with the increase in the molecular weight.
The chemical properties of these compounds closely resemble due to the presence of the same functional group (aldehyde group) in them.

Alkanes undergo only substitution reactions but alkenes and alkynes undergo both substitution and addition reactions. Why?

Auditor reaction involves addition of move atones to the

molecule or compound so usually

$\pi$ -bonds are takes away

and used as

$\sigma$ -bonds with the new atoms, ether than already

present

$\sigma -$ bonds being recreated

As it is easier to break

$\pi$ than

$\sigma$

Alkanes do not undergo addition reaction because they already

only have single

$\sigma -$ bounds, which cannot be more started

future and thus can only be swapped ( that give lies to

substitution reactions)

1123390_561810_ans_6f9e69646f84452eb74984e3603dc4ca.jpg

What is a homologous series? State any four characteristics of a homologous series?

Homologous series is a series of compounds with similar chemical properties and the same functional group differing from the successive member by

$-CH_2$ .
Example: The homologous series of straight-chain alkanes can be represented by the general formula

$C_nH_{2n+2}$

Thus the first four members of alkane homologous series are

$\displaystyle CH_4$ (methane),

$\displaystyle CH_3-CH_3$ (Ethane),

$\displaystyle CH_3-CH_2-CH_3$ (propane) and

$\displaystyle CH_3-CH_2-CH_2-CH_3$ (butane).

Characteristics of a homologous series are:
(i) Each member of the series can be represented by a general formula.
(ii) All the members of the series can be prepared by the same general methods.
(iii) Physical properties change throughout the series in a regular way.
(iv) Members of homologous series have similar chemical properties.

Name the simplest hydrocarbon.

Methane (

$CH_4$ ) is the simplest hydrocarbon. It is the first member of the alkane family. The general formula of the alkane family is

$C_nH_{2n+2}$ .

What will be the correct structural formula of product for the following reaction?

In 1st step, cyclic alkene is oxidised by dil

${ KMnO }_{ 4 }$ to give

$1,2-$ diol which on further oxidation give diketone through bond breaking. In presence of

${ OH }^{ \left( - \right) }$ ,

$C$ become cyclised to give

$E$ .

1094229_877189_ans_337aa66eee34410cb72ec22db250350e.png

Explain the nature of $C-X$ bond in both the compounds.

(i)

$CH_3-CH_2-CH_2-X$

$C-X$ bonds is purely single as no resonance is possible.

(ii) Refer to Image

$C-X$ bond has partial double bond character due to resonance.

$C_{3}H_{6}, C_{4}H_{8}$ and $C_{5}H_{10}$ belong to the same homologous series.
Arrange these hydrocarbons in order of increasing boiling points.

The boiling point of the hydrocarbons increases with the increasing molecular mass.
As molecular mass increases the intermolecular force of attractions (Van der Waal's force and London force) increases that require a higher amount of energy to break the bond.
Therefore, the correct order is $C_3H_6$ < $C_4H_8$ < $C_5H_{10}$

What are homologous series of carbon compounds? Write the molecular formula of two consecutive members of homologous series of aldehydes. State which part of these compounds determines their (i) physical and (ii) chemical properties.

A homologous series may be defined as a family of organic compounds having the same functional group, and the successive(adjacent) members of which differ by a

$CH_{2}$ unit or

$14$ mass units.

Two consecutive members of homologous series of Aldehydes:

$CH_{3}CHO$ and

$C_{2}H_{5}CHO$

A carbon compound is made up of two parts:

$R-F$ , where

$R$ is the hydrocarbon part and

$F$ is the functional group part.

So, this

$R$ (hydrocarbon) part determines the physical properties of a compound and the

$F$ (functional group) part determines the chemical properties of the compounds.

Complete the following reactions:

$CH_3 - CH_2 - C \equiv CH + H_20 \xrightarrow[40\%H_2SO_4]{1\% HgSO_4}$

1442817_879832_ans_9faa870bf1b24e0fbbd73eadefd92246.png

Name the gas evolved in each of the following cases:
(i) Copper carbonate is heated strongly.
(ii) Action of dilute hydrochloric acid on sodium sulphite.
(iii) Nitrogen combines with hydrogen.
(iv) Action of dilute sulphuric acid on sodium carbonate.
(v) Addition of sodium to cold water.

(i) When green copper carbonate {

${ CuCO }_{ 3 }$ } is heated it decomposes forming copper oxide {

$CuO$ } and carbon dioxide {

${ CO }_{ 2 }$ }.

(ii) when hydrochloric acid reacts with sodium sulphite, it forms sodium chloride and sulphur dioxide which gives smell of burning sulphur.

(iii) When hydrogen gas combines with nitrogen to form Ammonia the following chemical reaction will take place.

${ N }_{ 2 }+{ 3H }_{ 2 }\rightarrow { 2NH }_{ 3 }$

(iv) when dilute sulphuric acid reacts with sodium carbonate, carbon dioxide gas is evolved.

${ H }_{ 2 }{ SO }_{ 4 }+{ Na }_{ 2 }{ CO }_{ 3 }\rightarrow { Na }_{ 2 }{ SO }_{ 4 }+{ H }_{ 2 }O+{ CO }_{ 2 }$

(v) Sodium element is a very reactive metal. If a small amount of sodium is thrown in water, it usually wizzes on top reacting vigorously to form Sodium Hydroxide and Hydrogen gas.

What is a homologous series? Which two of the following organic compounds belong to the same homologous series?
$C_2H_6, C_2H_6O, C_2H_6O_2, CH_4O$

a homologous series is a series of compounds with the same functional group and similar chemical properties in which each successive member differs by

${ CH }_{ 2 }$ .Compounds within a homologous series typically have a fixed set of functional groups that gives them similar chemical and physical properties. The name "homologous series" is also often used for any collection of compounds that have similar structures or include the same functional group, such as the general alkanes (straight and branched), the alkenes (olefins), the carbohydrates, etc.

Here,

${ CH }_{ 4 }O$ and

${ C }_{ 2 }{ H }_{ 6 }O$ are of same homologous series. Both are differed by

${ CH }_{ 2 }$ .

$CH_3-\overset{O}{\overset{||}{C}}-OC_2H_5+NaNH_2\rightarrow$ ?

Now 2nd reaction will happen because

${ \overset { \left( - \right) }{ NH } }_{ 2 }$ is very strong base and it easily attracts a proton from ester.

1101588_1029348_ans_bd514f0b2583491698e677cbca55ddab.png

Write the major product in the following.
$2CH_3 - \underset{Cl}{\underset{|}{C}H} - CH_3 \xrightarrow[dry\, ether]{Na}$ ?
$CH_3 - CH_2 - Br \xrightarrow {AgCN}$ ?

1431912_1030108_ans_974cee32ce8d46fca3d1d170f07c700c.jpg

In the given reaction the product P is:

So, the product P is phenylcyclohexane

977058_1036782_ans_6946353daedd4c2e8f1e8e24d09a201a.png

Identify the product $C$ .

1st

${ CHBr }_{ 3 }$ reacts with base

${ t }_{ Bn }OK$ to

$:{ CBr }_{ 2 }$ carbene. Now this :

${ CBr }_{ 2 }$ inserts into one of the double bond of cyclopentadiene to form

$B$ which contains a three membered rings. Now breaking of three membered rings and simultaneous leaving of

${ Br }^{ \left( - \right) }$ gives

$C$ . Subsequently

$C$ gives an aromatic compound

$D$ which is bromo benzene.
1103154_1033589_ans_3aa103c274234aa6a35a1eeeab15fc22.png

What will be the major product formed?

Both

$-NO_2$ and

$-Cl$ is deactivating. But

$-Cl$ has ortho-para-directing effect. So, it dominates the ortho-effect over

$-NO_2$ meta effect.
990376_1028255_ans_59d04949c85b48be98d4950193c648ac.png

An aromatic organic compound [A] on heating with ${ NH }_{ 3 }$ and ${ Cu }_{ 2 }O$ at high pressure gives [B]. The compound [B] on treatment with ice cold solution of ${ NaNO }_{ 2 }$ and $HCL$ gives [C].Which on heating with $Cu/HCl$ gives compound [A] again. Identify the compounds [A], [B] and [C]. Write the name of the reaction for the conversion of [B] to [C] ?

Conversion of

$B$ to

$C$ is called Sand-Meyer reaction.
1157588_1048356_ans_8566088e11cf4b1eb297d01e82addd92.jpg

Identify the major product $P$ in the following reaction.

This reaction is known as nucleophilic by molecular substitution reaction

$(S_N2)$

1158321_1052122_ans_7ae3db1f9d3a4d628c1f9892bf67e65e.png

What is the major product obtained from the following reaction?
$CH_3\underset{\underset{Br}{|}}{C}H-CH_2-CH_3\xrightarrow[Et_2O]{CH_3ONa}$

The mechanism of reaction is

$SN^2$ due to the presence of strong solvent

$Et_2O$ .

Here the methyl group will substitute

$-Br$ group and inversion of the configuration takes place.

967901_1055374_ans_04ee5ad30c0e42ada0bfe1194b32cd89.png

What are the products obtained from the following reaction?

The mechanism of the reaction is

$SN^2$ due to the presence of strong solvent

$Et_2O$ .

Here the

$-Br$ group is substituted by

$-C\equiv CH$ group.

967907_1055396_ans_cfe58812f4ef462b9e05d1fd9278ec4e.png

$N_{2}H_{4}+ClO_{3}^{-} \rightarrow No+Cl^{-}$
Balance and complete the reaction.

$N:-2\rightarrow +2$

$Cl:+5\rightarrow -1$

$3{ N }_{ 2 }{ H }_{ 4 }+4Cl{ O }_{ 3 }\longrightarrow 6NO+4C{ l }^{ - }$

Now Balance:

$3{ N }_{ 2 }{ H }_{ 4 }+4Cl{ O }_{ 3 }\longrightarrow 6NO+4C{ l }^{ - }+6{ H }_{ 2 }O$

Write structures of the products A, B, C, D, and E in the following scheme.

In presence of

$Cl_{2}/FeCl_{3}$ , halogenation on benzene takes place on or the position to

$Cl$ , as

$Cl$ is o, p-directing group for electrophilic substitution.

On addition of

$Na-Hg/HCl$ Clemenson reduction takes place, which reduce carbonyl to alkane.

On addition of

$HNO_{3}$ , nitration takes place at para-position because at ortho -I effect of

$Cl$ will deactivate.

On addition of sodium salt nucleophilic attack takes place on para to

$NO_{2}$ as it is most deactivating group and ease the attack of nucleophilic.

On addition of

$H_{2}/Pd$ , reduction of

$NO_{2}$ and alkene takes place which gives product E.

1125065_1093981_ans_6aeacac8b5614f8baab474a153d02560.png

In this product A is?

(Refer to Image)

Inversion of configuration in

$SN^2$ condition.

1381113_1096204_ans_a7bf7c98b8f142ee8007972b186579ad.jpg

Find X.

In the first step, Michael addition or 1, 4-addition takes place at alkene not on carbonyl as the base is not that strong to attack the carbonyl.
1380793_1096512_ans_2521cfe126544e9f9d7a5496fa02bf8b.png

1380793_1096512_ans_2521cfe126544e9f9d7a5496fa02bf8b.png

The molecular formula of a compound is $C_{10}H_{18}$ . Name the homologous series to which it belongs.

Molecular formula is

$C_{10}H_{18}$

The given formula resemble the general formula

$C_nH_{2n-2}$ where

$n=10$

Therefore it belongs to alkynes.

What is reaction intermediate?

Reaction intermediate is formed from reactants in a chemical reaction, and react further to produce the final product.

A reaction intermediate is a transient species within a multi-step reaction mechanism that is produced in the preceding step and used in the next step to ultimately produce a final product.

1170825_1117278_ans_a8d180b6f4424ea496841dac1c6a9461.jpg

Define homologous series.

A homologous series is a series of compounds with similar chemical properties and the same functional group differing from the successive members by $-CH_2$ . Members of a homologous series can be represented by the same general formula.

(I) Draw the resonating structure of ${ C }_{ 6 }{ H }_{ 5 }{ NO }_{ 2 }$ and ${ C }_{ 6 }{ H }_{ 5 }OH$ .
(II) Why $\left( { CH }_{ 3 } \right) _{ 3 }{ C }^{ + }$ carbocation is more stable than ${ CH }_{ 3 }$ ?

1350759_1203360_ans_95c608e0b4c44e6a97fa27a6c7ff7100.jpg

Write a balanced equation for
(i) Silicon dioxide is treated with hydrogen fluoride
(ii) Boric acid is added to water
(iii) Diborane reacts with $NH_{3}$ followed by heating.

1397280_1235307_ans_e2044446b2ea4c9da93e440673c675bc.jpg

Write mechanisms for the following reaction
Phtochemical chlorination of methane

1316281_1371354_ans_8f57215910404fe291bc34a906909f24.PNG

Explain the mechanism of the following reaction :

1294394_1381005_ans_a93c619d67e54cce99d8c26c3b4d7259.PNG

Write the structure of A,B,C,D,and E in following

1294389_1389064_ans_5f3c82559eef4a80ae7fcae60823a96a.PNG

Define Decarboxylation. Methane is formed by decarboxylation

A carboxylic acid has the formula RCOOH where R can be hydrogen or a hydrocarbon group such as an alkyl group. The hydrocarbon group could equally well be based on a benzene ring.

The sodium salt of a carboxylic acid will have the formula RCOONa.

In decarboxylation, the -COOH or -COONa group is removed and replaced with a hydrogen atom.

How many $CO_2$ will releave in the following reaction

2 CO2 will release in the above reaction
1294368_1449967_ans_fa3f007e6c38421ab3d1554703966032.PNG

Write the molecular formula of first two members of homologous series having functional group $-Cl$ .

The general formula for the homologues series of functional group -Cl is

$C_{n}H_{2n+1}Cl$ .

The first two members of the series are:

(i)

$CH_{3}-Cl$ (Chloromethane)

(ii)

$CH_{3}CH_{2}-Cl$ (Chloroethane)

What happens when Acrylonitrile reacts with 1, 3-butadiene

1294376_1562057_ans_5b5cf0f1072b45708986117de52538df.PNG

Explain the mechanism of the following reaction.
$C_2H_5 OH \xrightarrow[443 \, K]{Conc. \, H_2SO_4} CH_2 = CH_2 + H_2O$

$\underset{\text{Ethanol}}{{C}_{2}{H}_{5}-OH} \xrightarrow[443 \; K]{\text{Conc. } {H}_{2}S{O}_{4}} \underset{\text{Ethene}}{C{H}_{2}=C{H}_{2}} + {H}_{2}O$

The given reaction is a dehydration reaction which turns ethanol

$\left( C{H}_{3}C{H}_{2}OH \right)$ into ethene

$\left( {C}_{2}{H}_{4} \right)$ . The concentrated

${H}_{2}S{O}_{4}$ is added as a catalyst. The acidic environment enables the alcohol group

$\left( -OH \right)$ to be more easily removed from the ethanol to form ethene.

Copy and complete the following table which relates to three homologous series of hydrocarbons:
General Formula $C_n H_{2n}$ $C_n H_{2n-2}$ $C_n H_{2n+2}$
$IUPAC$ name of the homologous series
Characteristic bond type Single Bond
$IUPAC$ name of the first member of the series
Type of reaction with chlorine Addition

General Formula	$C_n H_{2n}$	$C_n H_{2n-2}$	$C_n H_{2n+2}$
IUPAC name of the homologous series	Alkenes	Alkynes	Alkanes
Characteristic bond type	Double bond	Triple bond	Single bond
IUPAC name of the first member of the series	Ethene	Ethyne	Methane
Type of reaction with chlorine	Addition	Addition	Substitution

What is the difference in the number of carbon and hydrogen atoms between two successive members of a homologous series? Also, give the difference in their atomic masses.

The difference is of

$1$ carbon and two hydrogen atoms i.e., –

$CH_2$ , and the mass difference is

$14$ a.m.u.

What is the difference between the mass of two successive members of a homologous series of hydrocarbons?

$-CH_2= 12+2 = 14$
The difference between the mass of two successive members of the homologous series is

$14$ which means the

$CH_2$ group increases in the homologous series of hydrocarbons.

Give one example of homologous series, give two properties of it.

Homologous series: When the members of a hydrocarbon family obey the same general formula they are said to be in homologous series. The members in the series are arranged in increasing order of their molecular masses:
Example:
Alkane – $C_nH_{2n+2}$
$CH_4$ – Methane
$C_2H_6$ – Ethane
$C_3H_8$ – Propane
$C_4H_{10}$ – Butane
Properties:

The difference between two consecutive members of the homologous series is – $CH_2$ and mass $14$ a.m.u.
They all show the same chemical properties and slight gradation in their physical properties.

Name the following organic compounds :
The first homologue whose general formula is $C_nH_{2n}$ .

The name of the second member of homologous series is Ethene with chemical formula

$C_2H_4$ it belongs to the group of alkenes.

Write names of first four homologous series of alcohols :

1896900_1911245_ans_f2bec1707e6b49f5922c9a071c116d59.jpg

Match the reactions in List 1 with appropriate type of steps/reactive intermediates involved in these reactions as given in List 2.

(A) The given reaction involves two steps. The first step is the nucleophilic addition and the second step is the dehydration.
The hydroxide ion abstracts acidic proton to form carbonation. The carbanion attacks another carbonyl group (this is an intramolecular nucleophilic attack). This is followed by protonation of oxygen and dehydration to form the product.
(B) The given reaction is a nucleophilic substitution reaction in which chloride ion is substituted with a methyl group. The product is obtained by the rearrangement of the epoxide ring. The methyl group of the Grignard reagent attacks the terminal carbon atom of the epoxide ring to form oxide anion. The oxide anion then attacks the carbon-bearing chlorine atom.
(C) The given reaction involves two steps. The first step is the nucleophilic addition and the second step is the dehydration. The aldehyde oxygen atom is protonated. This is followed by the nucleophilic attack of the amine nitrogen on carbonyl carbon. The

$-OH$ group is then protonated and

$H_3O^+$ is lost.
(D) The given reaction involves electrophilic aromatic substitution and involves dehydration (loss of a molecule of water). It also involves the formation of a carbocation intermediate.
The

$-OH$ group is protonated. This is followed by electrophilic aromatic substitution.

Find product C in the given reaction.

The product formed is cyclohexene.
1392375_152347_ans_dac3db9834a94411bbf27bcb5182855b.jpg

Write the mechanism of the following reaction:

An equivalent of alcohol is protonated to its conjugate acid. Another equivalent of the alcohol then perform nucleophilic attack at carbon (

$S_N2$ ), leading to displacement of water

$OH_2$ and formation of a new

$C-O$ bond results in formation of

$ethoxy ethane$ .

$3, 3$ -Dimethylbutan- $2$ - ol loses a molecule of water in the presence of a concentrated sulphuric acid to give tetramethylethylene as a major product. Suggest a suitable mechanism.

This is done in 4 steps:

1. Protonation of hydroxyl group.

2. The removal of water to form a secondary carbonium ion.

3. The conversion of secondary carbonium to the more stable tertiary carbonium ion by the shift of methyl group.

4. The removal of

$H^+$ to form a double bond.

1141145_698750_ans_673cab60cae44554933d43e3a04a281c.png

Identify the product.

It is an electrophilic substitution reaction. It follows

$SN^1$ mechanism and the final products obtained are

$HCl$ and the above element.
1380716_867248_ans_338f46d13ea3452489543f87cb774f02.png

Which of the following reactions will get affected by increase in pressure? Also mention whether the change will cause the reaction to go to the right or left direction.
$CH_4(g) \,+\, 2S_2(g) \rightleftharpoons CS_2(g) \,+\, 2H_2S(g)$
$CO_2(g) \,+\, C(s) \rightleftharpoons 2CO(g)$
$4NH_3(g) \,+\, 5O_2(g) \rightleftharpoons 4NO(g) \,+\, 6H_2O(g)$
$C_2H_4 (g) \,+\, H_2(g) \rightleftharpoons C_2H_6(g)$
$COCl_2(g) \rightleftharpoons CO(g) \,+\, Cl_2(g)$
$CaCO_3 (s) \rightleftharpoons CaO(s) \,+\, CO_2(g)$

According to Le-Chatlier's principle,

When pressure increases, equilibrium shifts in the direction where pressure decreases

$C{ H }_{ 4(g) }+2{ S }_{ 2(g) }\rightleftharpoons C{ S }_{ 2(g) }+2{ H }_{ 2 }{ S }_{ \left( g \right) }\quad { n }_{ p }={ n }_{ r }$

No effect

ii)

$C{ O }_{ 2(g) }+{ C }_{ \left( s \right) }\rightleftharpoons 2C{ O }_{ \left( g \right) },{ n }_{ p }>{ n }_{ r }$

Backward reaction is favored

iii)

$4N{ H }_{ 3\left( g \right) }+5{ O }_{ 2\left( g \right) }\rightleftharpoons 4N{ O }_{ \left( g \right) }+6{ H }_{ 2 }{ O }_{ \left( g \right) }\quad { n }_{ r }>{ n }_{ p }$

Backward reaction is favored

iv)

${ C }_{ 2 }{ H }_{ 4\left( g \right) }+{ H }_{ 2\left( g \right) }\rightleftharpoons { C }_{ 2 }{ H }_{ 6\left( g \right) }\quad { n }_{ p }>{ n }_{ r }$

Forward reaction is favored

$CO{ Cl }_{ 2\left( g \right) }\rightleftharpoons C{ O }_{ \left( g \right) }+{ Cl }_{ 2\left( g \right) },\quad { n }_{ p }>{ n }_{ r }$

Shifts to backward direction

vi)

$CaC{ O }_{ 3\left( s \right) }\rightleftharpoons Ca{ O }_{ \left( s \right) }+C{ O }_{ 2\left( g \right) },{ n }_{ p }>{ n }_{ r }$

Backward reaction is favored

What is the major product of the following reaction?

$HBr$ gives nucleophilic addition reaction with alkene,

so the product will be

$6-bromo-6-methylheptane-2-ol$ .

964937_1021278_ans_8019d72c8d3141d1916ba9d04e258238.png

What is the Major product in the following reaction?

Since

$OTS^-$ is better leaving group, it proceeds via

$S_N2$ reaction resulting in inverted product.
1174117_1021348_ans_fcf6433d28674bcb8dba6b9f0de341d8.png

What is the major product in the above reaction?

1432420_1021285_ans_10ce544a861e4e1c9e0a6e2aebc0a642.png

What is the major product of the following reaction?

Reduction of keto leads to aromatization of ring takes place.
1157763_1021355_ans_11ac8655969342cb947f5335910e5db6.png

1163180_1033586_ans_fbf1cd0fe1cb4985a1badc30ae811662.png

Trichloroethanol may be prepared by the direct reduction of chloral hydrate in water with sodium borohydride. Suggest a mechanism for this reaction. (Warning! Sodium borohydride does not displace hydroxide from carbon atoms!)

$NaBH_4$ is a reducing agent and it reduces first chloral hydrate into corresponding carboxylic acid and then the acid is reduced to the trichloroethanol.

Thus,

$NaBH_4$ reduces carboxyl group to the alcohol.
990533_1067523_ans_6867d5d66c5446b587e26a8497ff9985.PNG

Identify the product $B$ .

Here

$A$ in presence of

${ HClO }_{ 4 }$ will form

$B$ easily, because

$A$ is not aromatic but

$B$ is aromatic due to presence of

$\left( 4n+2 \right) \Pi$ electrons in

$B$

$(n=0)$ . So aromaticity will be driving force for formation of

$B$ .

1103152_1033587_ans_e1e1b54aeccd42e7b928cabc560739c1.png

Visualize the formation of four particles in the given reaction.

1424529_1065947_ans_80033d03db1d484584ed847620229485.jpg

.

1424098_1067551_ans_4bb01a3ed75540d98a8a39c8a9531db0.png

Find $A$ and $B$ ?

1424109_1067481_ans_d6dd2ab9d6ee4d3e93a9c9a35fc85038.png

$A,A$ is:

(Refer to Image 1)

Lithium aluminium hydride attack from less hindered site.

(Refer to Image 2)

1172878_1070212_ans_7a884401c2d6447d97d4d631c504c911.png

What is the product formed?

The

$NaBH_4$ or Sodium Borohydride is a mild reducing agent thus it does not reduce carboxylic acid group, thus it will only reduce the ketonic group to corresponding alcohol.
969904_1070505_ans_b896d08661ff4801bdd3d4a2908250e9.PNG

969904_1070505_ans_b896d08661ff4801bdd3d4a2908250e9.PNG

Product $A$ and $B$ formed in the following reactions are respectively.

(Refer to Image 1)

In the first step in presence of

$HNO_2$ diazotization reaction takes place which gives the product. Then upon adding aniline it gives the product B. Aniline will attach through a para position as

$NH_2$ is para directive group.

(Refer to Image 2)

1099820_1068474_ans_ed67cd9de29248739af44083331803cf.png

(a) What is a homologous series? Explain with an example.
(b) State two characteristics of a homologous series.
(c) The molecular formula of an organic compound is $C_{18}H_{36}$ . Name its homologous series.
(d) Select the hydrocarbons which belong to the same homologous series. Give the name of each series.
$CH_{4}, C_{2}H_{2}, C_{3}H_{4}, C_{2}H_{6}, C_{4}H_{10}, C_{3}H_{4}, C_{3}H_{6}$ .
(e) What is meant by 'heteroatom'? Give examples. Write the names and formulae of two organic compounds containing different heteroatoms.

(a) A homologous series is a group of organic compounds having similar structures and similar chemical properties in which the successive compounds differ by

$CH_{2}$ group.

Example of Homologous series : All the alkanes have similar structures with single covalent bonds and show similar chemical properties, so they can be grouped together in the form of a homologous series.

Homologous series of alkanes : Methane,

$CH_{4}$ ; Ethane,

$C_{2}H_{6}$ ; Propane,

$C_{3}H_{8}$ ; Butane,

$C_{4}H_{10}$ ; Pentane,

$C_{5}H_{12}$

(b) (i) All the members of the homologous series can be represented by the same general formula.
(ii) Any two adjacent homologues differ by

$1$ carbon atom and

$2$ hydrogen atoms in their molecular formulae.

$C_{n}H_{2n}$

(d) Alkanes :

$CH_{4}, C_{2}H_{6}, C_{4}H_{10}$
Alkenes :

$C_{2}H_{4}, C_{3}H_{6}$
Alkynes :

$C_{2}H_{2}, C_{3}H_{4}$

(e) In an organic compound, any atom other than carbon and hydrogen is called a heteroatom.
Example: Chlorine

$(Cl)$ , Bromine

$(Br)$ , Oxygen

$(O)$
Chloromethane -

$CH_{3}Cl$ and methanol -

$CH_{3}OH$ .

Match each of the compounds given in Column I with the reaction(s), that they can undergo with one or or more statement(s), given in Column II.

1660986_1722562_ans_600ec23e90d942fba362d8face7442df.jpg

$2,2-Dimethyloxirane$ can be cleaved by acid $\mathrm{(H^{\oplus})}$ . Write the mechanism.

Cleavation of 2,2-dimethyl oxirane can be illustrated by above mechanism.
1785456_1769689_ans_36fb735df8a740c8b30096fa39869590.png

Match each of the compounds given in Column I with the reaction(s) they can undergo given in Column II.

$(d \rightarrow p)$ Since the ring contains EWG

$(-NO_2)$ group at o-position, the ring is activated for

$ArSN$ (aromatic nucleophilic substitution) to occur.

1788310_1769997_ans_95a11eef32294d8bbf53923cc64c529a.png

What is the suitable adsorbent in the process of column chromography?

1910356_1826775_ans_9c8dfe8096504f279df9cb597909d91b.JPG

How do the boiling point and melting point change in the homologous series of alcohols?

The melting and boiling point of the successive members of the homologous series of alcohols increase with the increase in molecular mass.

What is the difference in the molecular formula of any two adjacent homologues:
in terms of molecular mass.

The difference in molecular formula of any two adjacent homologues is:

It differs by

$14$ a.m.u in terms of molecular mass.

Give the names and the structural formula of the first three members of the homologous series of alkanes.

The names and the structural formula of first three members of the homologous series of alkane are:

(i) Methane

$(CH_{4})$

(ii) Ethane

$(C_{2}H_{6})$

(iii) Propane

$(C_{3}H_{8})$

1705750_1807531_ans_a38e41be2ff441bda6513c82bd888cf1.png

Organic Chemistry - Some Basic Principles And Techniques - Class 11 Engineering Chemistry - Extra Questions

What would be the product of NaOHNaOHNaOH + SiO2SiO2SiO_2 →→\rightarrow ?

Identify A,B,CA,B,CA, B, C and DDD.

How many (x) moles of HI consumed?

Match the column.Column (I) - E2E2E_2 reaction (elimination biomolecular)Column (II) - No. of possible products. (including stereoisomerism)

What is the product formed?

Find the product of the given reaction.

Provide a detailed reaction mechanism for the following.

Fill in the following blanks with suitable words:The next higher homologue of ethanol is ________.

The next higher homologue of ethane is _______.

Fill in the following blanks with suitable words:The next homologue of C2H5OHC2H5OHC_{2}H_{5}OH is _______

Identify the unknown organic compounds (D)(D)(D) to (E)(E)(E) in the following series of chemical reactions.(D)H2/Ni→Δ(E)(D)H2/Ni−−−−→Δ(E)(D)\xrightarrow [ \Delta ]{ H_{2}/Ni } (E)

Write the next homologue of each of the following:(i) C2H4C2H4 C_{2}H_{4} (ii) C4H6C4H6 C_{4}H_{6}

What is the next homologue of C3H7OHC3H7OH C_{3}H_{7}OH called?

Which two of the following organic compounds belong to the same homologous series?C2H6,C2H6O,C2H4O2,CH4OC2H6,C2H6O,C2H4O2,CH4O C_{2}H_{6},C_{2}H_{6}O,C_{2}H_{4}O_{2},CH_{4}O

Fill in the blanks:Propane and ethane are ________

The molecules of alkene family are represented by a general formula CnH2nCnH2nC_nH_{2n}. Answer the following:Write the molecular formula of lower and higher homologous of an alkene which contains four carbon atoms.

The molecular formula of the first member of a certain group of organic compound is CH2OCH2OCH_{2}O. Determine the name and molecular formula of the third member of this group if the member of this group are in series what is the general name of this group of organic compounds?

Find the final product.

The product is?

Write the name and formula of the 2nd member of homologous series having general formula CnH2n{C_n}{H_{2n}}.

In homologous series of aldehyde, the consecutive members of the series differ by the mass of:

Alkanes undergo only substitution reactions but alkenes and alkynes undergo both substitution and addition reactions. Why?

What is a homologous series? State any four characteristics of a homologous series?

Name the simplest hydrocarbon.

What will be the correct structural formula of product for the following reaction?

Explain the nature of C−XC-X bond in both the compounds.

C3H6,C4H8C_{3}H_{6}, C_{4}H_{8} and C5H10C_{5}H_{10} belong to the same homologous series.Arrange these hydrocarbons in order of increasing boiling points.

What are homologous series of carbon compounds? Write the molecular formula of two consecutive members of homologous series of aldehydes. State which part of these compounds determines their (i) physical and (ii) chemical properties.

Complete the following reactions:CH3−CH2−C≡CH+H201%HgSO4→40%H2SO4CH_3 - CH_2 - C \equiv CH + H_20 \xrightarrow[40\%H_2SO_4]{1\% HgSO_4}

Name the gas evolved in each of the following cases:(i) Copper carbonate is heated strongly.(ii) Action of dilute hydrochloric acid on sodium sulphite.(iii) Nitrogen combines with hydrogen.(iv) Action of dilute sulphuric acid on sodium carbonate.(v) Addition of sodium to cold water.

What is a homologous series? Which two of the following organic compounds belong to the same homologous series?C2H6,C2H6O,C2H6O2,CH4OC_2H_6, C_2H_6O, C_2H_6O_2, CH_4O

CH3−O||C−OC2H5+NaNH2→CH_3-\overset{O}{\overset{||}{C}}-OC_2H_5+NaNH_2\rightarrow?

Write the major product in the following.2CH3−C|HCl−CH3Na→dryether2CH_3 - \underset{Cl}{\underset{|}{C}H} - CH_3 \xrightarrow[dry\, ether]{Na} ?CH3−CH2−BrAgCN→CH_3 - CH_2 - Br \xrightarrow {AgCN} ?

In the given reaction the product P is:

Identify the product CC.

What will be the major product formed?

Identify the major product PP in the following reaction.

What is the major product obtained from the following reaction?CH3C|BrH−CH2−CH3CH3ONa→Et2OCH_3\underset{\underset{Br}{|}}{C}H-CH_2-CH_3\xrightarrow[Et_2O]{CH_3ONa}

What are the products obtained from the following reaction?

N2H4+ClO−3→No+Cl−N_{2}H_{4}+ClO_{3}^{-} \rightarrow No+Cl^{-}Balance and complete the reaction.

Write structures of the products A, B, C, D, and E in the following scheme.

In this product A is?

Find X.

The molecular formula of a compound is C10H18C_{10}H_{18}. Name the homologous series to which it belongs.

What is reaction intermediate?

Define homologous series.

(I) Draw the resonating structure of C6H5NO2{ C }_{ 6 }{ H }_{ 5 }{ NO }_{ 2 } and C6H5OH{ C }_{ 6 }{ H }_{ 5 }OH.(II) Why (CH3)3C+\left( { CH }_{ 3 } \right) _{ 3 }{ C }^{ + } carbocation is more stable than CH3{ CH }_{ 3 }?

Write a balanced equation for (i) Silicon dioxide is treated with hydrogen fluoride(ii) Boric acid is added to water(iii) Diborane reacts with NH3NH_{3} followed by heating.

Write mechanisms for the following reaction Phtochemical chlorination of methane

Explain the mechanism of the following reaction :

Write the structure of A,B,C,D,and E in following

Define Decarboxylation. Methane is formed by decarboxylation

How many CO2CO_2 will releave in the following reaction

Write the molecular formula of first two members of homologous series having functional group −Cl-Cl.

What happens when Acrylonitrile reacts with 1, 3-butadiene

Explain the mechanism of the following reaction.C2H5OHConc.H2SO4→443KCH2=CH2+H2OC_2H_5 OH \xrightarrow[443 \, K]{Conc. \, H_2SO_4} CH_2 = CH_2 + H_2O

What is the difference in the number of carbon and hydrogen atoms between two successive members of a homologous series? Also, give the difference in their atomic masses.

What is the difference between the mass of two successive members of a homologous series of hydrocarbons?

Give one example of homologous series, give two properties of it.

Name the following organic compounds : The first homologue whose general formula is CnH2nC_nH_{2n}.

Write names of first four homologous series of alcohols :

Match the reactions in List 1 with appropriate type of steps/reactive intermediates involved in these reactions as given in List 2.

Find product C in the given reaction.

Write the mechanism of the following reaction:

3,33, 3-Dimethylbutan- 22- ol loses a molecule of water in the presence of a concentrated sulphuric acid to give tetramethylethylene as a major product. Suggest a suitable mechanism.

Identify the product.

What is the major product of the following reaction?

What is the Major product in the following reaction?

What is the major product in the above reaction?

What is the major product of the following reaction?

Trichloroethanol may be prepared by the direct reduction of chloral hydrate in water with sodium borohydride. Suggest a mechanism for this reaction. (Warning! Sodium borohydride does not displace hydroxide from carbon atoms!)

Identify the product BB.

Visualize the formation of four particles in the given reaction.

.

Find AA and BB?

A,AA,A is:

What is the product formed?

Product AA and BB formed in the following reactions are respectively.

Match each of the compounds given in Column I with the reaction(s), that they can undergo with one or or more statement(s), given in Column II.

What would be the product of
$NaOH$ + $SiO_2$ $\rightarrow$ ?

Identify $A, B, C$ and $D$ .

Match the column.
Column (I) - $E_2$ reaction (elimination biomolecular)
Column (II) - No. of possible products. (including stereoisomerism)

Fill in the following blanks with suitable words:
The next higher homologue of ethanol is ________.

Fill in the following blanks with suitable words:
The next homologue of $C_{2}H_{5}OH$ is _______

Identify the unknown organic compounds $(D)$ to $(E)$ in the following series of chemical reactions.
$(D)\xrightarrow [ \Delta ]{ H_{2}/Ni } (E)$

Write the next homologue of each of the following:
(i) $C_{2}H_{4}$
(ii) $C_{4}H_{6}$

What is the next homologue of $C_{3}H_{7}OH$ called?

Which two of the following organic compounds belong to the same homologous series?
$C_{2}H_{6},C_{2}H_{6}O,C_{2}H_{4}O_{2},CH_{4}O$

Fill in the blanks:
Propane and ethane are ________

The molecules of alkene family are represented by a general formula $C_nH_{2n}$ . Answer the following:
Write the molecular formula of lower and higher homologous of an alkene which contains four carbon atoms.

The molecular formula of the first member of a certain group of organic compound is $CH_{2}O$ . Determine the name and molecular formula of the third member of this group if the member of this group are in series what is the general name of this group of organic compounds?

Write the name and formula of the 2nd member of homologous series having general formula ${C_n}{H_{2n}}$ .

Explain the nature of $C-X$ bond in both the compounds.

$C_{3}H_{6}, C_{4}H_{8}$ and $C_{5}H_{10}$ belong to the same homologous series.
Arrange these hydrocarbons in order of increasing boiling points.

Complete the following reactions:

$CH_3 - CH_2 - C \equiv CH + H_20 \xrightarrow[40\%H_2SO_4]{1\% HgSO_4}$

Name the gas evolved in each of the following cases:
(i) Copper carbonate is heated strongly.
(ii) Action of dilute hydrochloric acid on sodium sulphite.
(iii) Nitrogen combines with hydrogen.
(iv) Action of dilute sulphuric acid on sodium carbonate.
(v) Addition of sodium to cold water.

What is a homologous series? Which two of the following organic compounds belong to the same homologous series?
$C_2H_6, C_2H_6O, C_2H_6O_2, CH_4O$

$CH_3-\overset{O}{\overset{||}{C}}-OC_2H_5+NaNH_2\rightarrow$ ?

Write the major product in the following.
$2CH_3 - \underset{Cl}{\underset{|}{C}H} - CH_3 \xrightarrow[dry\, ether]{Na}$ ?
$CH_3 - CH_2 - Br \xrightarrow {AgCN}$ ?

Identify the product $C$ .

Identify the major product $P$ in the following reaction.

What is the major product obtained from the following reaction?
$CH_3\underset{\underset{Br}{|}}{C}H-CH_2-CH_3\xrightarrow[Et_2O]{CH_3ONa}$

$N_{2}H_{4}+ClO_{3}^{-} \rightarrow No+Cl^{-}$
Balance and complete the reaction.

The molecular formula of a compound is $C_{10}H_{18}$ . Name the homologous series to which it belongs.

(I) Draw the resonating structure of ${ C }_{ 6 }{ H }_{ 5 }{ NO }_{ 2 }$ and ${ C }_{ 6 }{ H }_{ 5 }OH$ .
(II) Why $\left( { CH }_{ 3 } \right) _{ 3 }{ C }^{ + }$ carbocation is more stable than ${ CH }_{ 3 }$ ?

Write a balanced equation for
(i) Silicon dioxide is treated with hydrogen fluoride
(ii) Boric acid is added to water
(iii) Diborane reacts with $NH_{3}$ followed by heating.

Write mechanisms for the following reaction
Phtochemical chlorination of methane

How many $CO_2$ will releave in the following reaction

Write the molecular formula of first two members of homologous series having functional group $-Cl$ .

Explain the mechanism of the following reaction.
$C_2H_5 OH \xrightarrow[443 \, K]{Conc. \, H_2SO_4} CH_2 = CH_2 + H_2O$

Name the following organic compounds :
The first homologue whose general formula is $C_nH_{2n}$ .

$3, 3$ -Dimethylbutan- $2$ - ol loses a molecule of water in the presence of a concentrated sulphuric acid to give tetramethylethylene as a major product. Suggest a suitable mechanism.

Identify the product $B$ .

Find $A$ and $B$ ?

$A,A$ is:

Product $A$ and $B$ formed in the following reactions are respectively.

$2,2-Dimethyloxirane$ can be cleaved by acid $\mathrm{(H^{\oplus})}$ . Write the mechanism.

What is the difference in the molecular formula of any two adjacent homologues:
in terms of molecular mass.