Acetylene can be converted to 1-Bromo pentane via coupling of 1-Bromopropane. The set of reagents required are :
NaNH2, CH3CH2CH2Br; H2/Lindlar cut; HBr, H2O2
Step 1 (chain extension): NaNH2 deprotonates acetylene to the acetylide ion, which displaces bromide from 1-bromopropane by SN2: HC≡CH → HC≡C–Na+ → HC≡C–CH2CH2CH3 (1-pentyne, five carbons).
Step 2 (partial reduction): H2 over Lindlar catalyst (Pd/CaCO3 poisoned with lead acetate and quinoline) stops at the alkene: 1-pentyne → CH2=CH–CH2CH2CH3 (1-pentene).
Step 3 (anti-Markovnikov addition): HBr in the presence of a peroxide (H2O2) adds by a free-radical chain; Br· adds to the terminal CH2 to give the more stable secondary radical, so bromine ends up on C-1: CH2=CHCH2CH2CH3 → BrCH2CH2CH2CH2CH3 (1-bromopentane).
Using H2, Pd/C reduces the alkyne all the way to pentane, which does not react with HBr; LiAlH4 does not reduce a simple terminal alkyne to the alkene; and HBr without peroxide adds by Markovnikov's rule to give 2-bromopentane.
Therefore the sequence is NaNH2/1-bromopropane, then H2/Lindlar catalyst, then HBr with H2O2.
Hence, NaNH2, CH3CH2CH2Br; H2/Lindlar cut; HBr, H2O2.
Important Questions from Mixed Topic (MH-SET)
.................... is a client server application that identifies each host on the internet with a unique user-friendly name.
Every OS has a ................ or .......... which primarily resides in the main memory of the computer to perform some of the basic functions of the OS.
(i) Kernel
(ii) Interface
(iii) Nucleus
(iv) Compiler
Codes:
Which of the following are referred to as low level language?
(i) Machine language
(ii) Assembly language
(iii) High level language
(iv) Natural language
Codes:
Match the following:
List I List II (a) New York Public Library (i) Shelv AR (b) Miami University Augmented Research Group (ii) Smart library (c) Oula University Library (iii) Wolf Walk (d) North Carolina State University (iv) Find the future Codes:
Which part of the QR code represents the encoded data?
