default_background
✕

Find the best tutors and institutes for Class 12 Tuition

Find Best Class 12 Tuition

Please select a Category.

Please select a Locality.

No matching category found.

No matching Locality found.

Q6.14(vii):

Write the structure of the major organic product in each of the following reactions:

Solution :

Given Reaction Analysis

The substrate is $1$-bromobut-2-ene ($CH_3-CH=CH-CH_2Br$). The reagent is $CH_3ONa$ (Sodium methoxide), which is a strong nucleophile and a strong base, acting in its conjugate acid, methanol ($CH_3OH$).

Step 1: Identifying the Reaction Mechanism

Since the substrate is a primary allylic halide reacting with a strong alkoxide base ($CH_3O^-$), the reaction follows a competition between $S_N2$ (bimolecular nucleophilic substitution) and $E2$ (bimolecular elimination). However, in the presence of strong base/heat, elimination is favored. Furthermore, allylic systems are prone to resonance stabilization of the intermediate/transition state.

Step 2: Analysis of the Nucleophilic Attack ($S_N2$)

The methoxide ion attacks the $\alpha$-carbon of the allylic halide. Due to the presence of the conjugated double bond, the nucleophile can attack the primary carbon (direct substitution) or the $\gamma$-carbon (allylic rearrangement).

  • Direct Substitution: $CH_3-CH=CH-CH_2-OCH_3$ ($1$-methoxybut-$2$-ene)
  • Rearranged Substitution: $CH_3-CH(OCH_3)-CH=CH_2$ ($3$-methoxybut-$1$-ene)

Step 3: Determining the Major Product

In the presence of $CH_3ONa/CH_3OH$, the substitution product $1$-methoxybut-$2$-ene is favored due to lower steric hindrance at the primary carbon compared to the secondary position and the stability of the conjugated system. However, standard textbook synthesis for these conditions identifies the direct substitution product as the major organic product.

CH₃-CH=CH-CHβ‚‚Br + CH₃ONa S_N2 CH₃-CH=CH-CHβ‚‚-OCH₃ + NaBr

Step 4: Chemical Justification

The reaction proceeds via an $S_N2$ mechanism [Per the kinetics of nucleophilic substitution]. The transition state involves the concerted displacement of the bromide ion by the methoxide nucleophile. Because the transition state involves the $\pi$ system of the alkene, the primary carbon is sufficiently electrophilic to undergo rapid substitution. The product formed, $1$-methoxybut-$2$-ene, retains the internal double bond which is thermodynamically more stable than the terminal alkene isomer [Per Zaitsev's rule and thermodynamic stability of substituted alkenes].

Reactant Reagent Mechanism Major Product
$CH_3-CH=CH-CH_2Br$ $CH_3ONa/CH_3OH$ $S_N2$ $CH_3-CH=CH-CH_2OCH_3$

Final Solution: The major organic product is $1$-methoxybut-$2$-ene ($CH_3-CH=CH-CH_2OCH_3$).


More Questions from Class 12 Chemistry Haloalkanes and Haloarenes Exercises


CBSE Solutions for Class 12 Chemistry Haloalkanes and Haloarenes


Chapters in CBSE - Class 12 Chemistry


Top Tutors who teach Haloalkanes and Haloarenes

(61)
Top Tutor
locationImg HMT Estate 2nd Stage, Bangalore
experience 20 yrs of Exp students 37 students
greenClock 2764 hrs of classes completed
rsIcon 600 per hour
I am a teaching professional with 15 years of experience and over 2500 hours of online teaching
Online Classes Online Classes

I am a teacher. Teaching chemistry for the past 20+ years. I also have some experience in research in applied chemistry. I have a masters degree in chemistry and a bachelors degree in education. In addition to teaching I have experience in school administration and content development. My key skills are to train the students for various competitive exams like JEE, NEET, BITSAT, CET.

Skills: Chemistry
Also teaches: NEET-UG Coaching, Class 11 Tuition and more

Dr. ragini J. Class 12 Tuition trainer in Lucknow
(56)
Top Tutor
locationImg Chandralok, Lucknow
experience 20 yrs of Exp students 48 students
greenClock 2308 hrs of classes completed
rsIcon 400 per hour
Professional with more than 25 years of teaching experience in higher education
Online Classes Online Classes
regularClasses Tutor's home

It was fabulous. Class 12 kids are very honest in stating if they understood or not and that helps a lot to teach them.

Pradeep Marshal

Ragini ma’am is an amazing teacher who explains every concept in a very clear and simple way. Her guidance, support, and constant motivation helped me score really good marks in my boards. Truly grateful for all her hard work and support throughout the year

Skills: Economics , Accounts and more
Also teaches: MBA Tuition, BCom Tuition and more

(42)
Top Tutor
locationImg Sector 49, Gurgaon
experience 12 yrs of Exp students 1 student
greenClock 1 hrs of classes completed
rsIcon 1400 per hour
Accounts & Economics Teacher with 12 years of experience CBSE ICSE & IB
homeTutions Student's Home

Focus is on building the fundamentals of both Accounting and economics and making it easy to understand. Have been delivering excellent and above anticipated results. A good score follows with better understanding of the concepts. Learning is fun with the way we do our classes. Must take a demo before making up the mind for starting or not to start the classes.

Yashovardhan Chauhan

Sudhanshu Sir is an excellent economics teacher who explains every concept in a very simple and clear way. His teaching style makes even difficult topics easy to understand, and he is always patient while solving doubts. Thanks to his guidance, my interest and confidence in economics have improved a lot.

Skills: Economics , Business and Management and more

(203)
Top Tutor
locationImg Venkatraman Nagar Chennai, Chennai
experience 10 yrs of Exp students 26 students
greenClock 4290 hrs of classes completed
rsIcon 400 per hour
Expereinced Tutor for class 9- class 12 on maths and sxience subjects
Online Classes Online Classes

I am a software engineer working in MNC company. However i do like to teach maths and science subjects. I have a good experience in teaching maths and science and great in make them understanding the concepts in a most practical way and made them to score high marks.

Bharathi Stephen

The sessions are very interactive, he provides lots of worksheets and Test papers to strengthen the concepts. He doesn't rush through any topic and is ready to clear our doubts even when asked multiple times.

Skills: Chemistry
Also teaches: Class 9 Tuition, Class 6 Tuition and more

(51)
Top Tutor
locationImg Gulshan Bellina Rd Greater Noida, Noida
experience 10 yrs of Exp students 18 students
greenClock 255 hrs of classes completed
rsIcon 500 per hour
I teach accounts to 11th & 12th students..
homeTutions Student's Home

My name is have a B.Com degree from graduation and an M.Com degree for master's . Apart from this, I have cleared the CA Inter course . I have been teaching accountancy subjects for the last 10 years to Class 11 & Class 12 students. There are so many students who took classes from me and have scored well in their exams . The only reason for this is that the students' concepts are cleared very well.

Neelam Sharma

"Mujhe apne Accountancy teacher se kaafi kuch seekhne ko mila. Unka teaching style bahut hi engaging aur clear hai, jo har complex topic ko bhi simple bana deta hai. Har lesson practical examples ke saath hota hai, jo humare liye easily samajhna possible banata hai. Unke dedication aur passion ki wajah se hum Accountancy ko na sirf samajh paate hain, balki enjoy bhi karte hain. Best teacher ever!" β˜ΊπŸ™πŸ»

Skills: Accounts , Accountancy
Also teaches: Class 11 Tuition

Other Subjects in CBSE - Class 12

Worksheet Icon

Download free CBSE - Class 12 Chemistry Haloalkanes and Haloarenes Exercises worksheets

Download Now

Find Best Class 12 Tuition ?

Find Now »