Grignard S Reagents And Their Uses

Step 1: Possible alkyl groups with 4 carbon atoms.
We can form different structural isomers of butyl groups (C₄H₉–) as the alkyl part $R$ . There are four distinct isomeric forms:

n-Butyl bromide $CH_3%20-%20CH_2%20-%20CH_2%20-%20CH_2Br$
sec-Butyl bromide $CH_3%20-%20CHBr%20-%20CH_2%20-%20CH_3$
iso-Butyl bromide $(CH_3)_2CH%20-%20CH_2Br$
tert-Butyl bromide $(C%20H_3)_3CBr$

Each of these has a unique arrangement of carbon atoms and bromine, leading to different structures and physical properties.

Step 2: Total number of possible structures

$%5Cboxed%7B%5Ctext%7BTotal%20number%20of%20possible%20structures%20of%20%7D%20RBr%20%3D%204%7D$

Final Answer:

$%5Cboxed%7B4%20%5Ctext%7B%20isomeric%20structures%20of%20%7D%20RBr%20%5Ctext%7B%20(C%7D_4H_9Br)%7D$

Quick Concept:

For alkyl halides $R%E2%80%93X$ , the number of possible structures corresponds to the number of structural isomers of the alkyl group $R$ . For butyl bromide, these are: n-butyl, sec-butyl, iso-butyl, and tert-butyl bromide.

Step 1: Understanding the Concept:
Grignard reagents react with compounds containing active hydrogen (like water) to produce alkanes. The molar mass of the liberated gas identifies the alkyl group R. Subsequent reactions include the iodination of alkanes and the Wurtz reaction.
: Key Formula or Approach:
1. Reaction:

RMgI%20%2B%20H_2O%20%5Cto%20RH%20%2B%20Mg(OH)I

.
2. Molar mass

M%20%3D%20%5Cfrac%7B%5Ctext%7BMolar%20Volume%20at%20STP%7D%7D%7B%5Ctext%7BSpecific%20Volume%7D%7D

.
3. Wurtz Reaction:

2R-X%20%2B%202Na%20%5Cxrightarrow%7B%5Ctext%7Bether%7D%7D%20R-R%20%2B%202NaX

.
Step 2: Detailed Explanation:
1. Identification of the gas:
Molar volume at STP = 22.4 L/mol = 22.4 dm

%5E3

/mol.
Specific volume of the gas = 1.4 dm

%5E3

/g.
Molar mass of the gas (

RH

) =

%5Cfrac%7B22.4%20%5Ctext%7B%20dm%7D%5E3%2F%5Ctext%7Bmol%7D%7D%7B1.4%20%5Ctext%7B%20dm%7D%5E3%2F%5Ctext%7Bg%7D%7D%20%3D%2016%20%5Ctext%7B%20g%2Fmol%7D

.
The alkane with molar mass 16 is Methane (

CH_4

). Thus, the alkyl group

R

is Methyl (

-CH_3

).
2. Formation of Compound (X):
Methane reacts with

I_2

in the presence of

HIO_3

(which removes

HI

to prevent the reversible reaction):

CH_4%20%2B%20I_2%20%5Cxrightarrow%7BHIO_3%7D%20CH_3I%20%2B%20HI

.
So, Compound (X) is Methyl iodide (

CH_3I

).
3. Formation of Compound (Y):
Methyl iodide undergoes the Wurtz reaction with Sodium in dry ether:

2CH_3I%20%2B%202Na%20%5Cxrightarrow%7B%5Ctext%7Bether%7D%7D%20CH_3-CH_3%20%2B%202NaI

.
So, Compound (Y) is Ethane (

C_2H_6

).
4. Molar mass of (Y):
Molar mass of

C_2H_6%20%3D%202(12)%20%2B%206(1)%20%3D%2030%20%5Ctext%7B%20g%2Fmol%7D

.
Step 3: Final Answer:
The molar mass of compound (Y) is 30 g mol

%5E%7B-1%7D

About Grignard S Reagents And Their Uses - JEE-MAIN

Grignard S Reagents And Their Uses is a vital chapter for JEE-MAIN aspirants. Mastering the concepts covered in this chapter is essential for securing a top rank.

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Review the topic breakdown to see which sub-topics within Grignard S Reagents And Their Uses carry the most weight. Then, tackle the questions iteratively to solidify your understanding.

High-Yield Trend

Chapter Questions
2 MCQs

Official Solution

Step 2: Total number of possible structures

Final Answer:

Quick Concept:

Official Solution

About Grignard S Reagents And Their Uses - JEE-MAIN

Frequently Asked Questions

Why focus on Grignard S Reagents And Their Uses PYQs?

How to best use this analysis?

Grignard S Reagents And Their Uses

High-Yield Trend

Chapter Questions 2 MCQs

Official Solution

Step 2: Total number of possible structures

Final Answer:

Quick Concept:

Official Solution

About Grignard S Reagents And Their Uses - JEE-MAIN

Frequently Asked Questions

Why focus on Grignard S Reagents And Their Uses PYQs?

How to best use this analysis?

Chapter Questions
2 MCQs