Name of the Organization : Homi Bhabha Centre For Science Education
Name Of The Exam : Indian National Chemistry Olympiad – 2017
Document Type : Sample Question Paper
Subject : Chemistry
Year : 2017

Website : http://olympiads.hbcse.tifr.res.in/?page_id=1376#QS
Download Model/Sample Question Papers : http://www.indianjobtalks.com/upload...NChemistry.pdf

Indian National Chemistry Olympiad Question Paper :
Instructions for students :
** Write your Roll No. at the top of all pages.
** This examination paper consists of 29 pages of problems including answer boxes.

** Kindly check that the booklet has all the pages.
** Blank space for rough work has been provided at the end of the paper.
** Use only a pen to write the answers in the answer boxes. Anything written by pencil will not be considered for assessment.

** All answers must be written in the appropriate boxes. Anything written elsewhere will not be considered for
assessment.
** You must show the main steps in the calculations.
** For objective type question, mark X in the correct box. Some of the objective questions may have more than one correct answer.

** A copy of the Periodic Table of the Elements is provided on the 2nd page of the paper.
** Do not leave the examination room until you are directed to do so.
** The question paper will be uploaded on the HBCSE website on 31st January 2017

Problem 1 : 17 Marks
Barbiturates in our lives Guano, the excreta of sea birds and bats was a major export item from colonial America to Europe in the 19th century used for making fertilizers and extracting uric acid, which was used to produce many commercial chemicals including the valuable dye Murexide. Uric acid is a metabolic by-product of proteins and nucleic acids. German chemist Adolf von Baeyer in 1864, while studying the chemistry of uric acid, discovered barbituric acid C. Derivatives of this compound were very effective in inducing sleep in animals. Later, this family of compounds turned out to be very effective drugs for human psychological disorders.

1.1 Draw structures for A and B.
Thiopental, popularly known as “truth serum”, which makes people to speak more (often revealing the truth) was soon discovered. It has a ring structure similar to C. Its preparation involves reacting 2-ethylpropanedioic acid diethyl ester with racemic 2-bromopentane in the presence of sodium ethoxide to form product D (C14H26O4). D obtained, is a racemic mixture, which condenses with thiourea to give Thiopental (E) (C11H18N2O2S). The „R? isomer of Thiopental is a mood elevator and the „S? isomer causes neurological depression.

1.2 Draw the structure of D and the two isomers of E and label them with „R? and „S? configuration
1.3 Compound C is quite acidic (pKa = 4.01). Draw the structures of the most stable tautomers of the conjugate base of C. The tautomers should be unique and not resonance structures of each other.

1.4 F is formed in the CrO3 oxidation of the condensation product G of benzaldehyde and C in the presence of piperidine (a base). Draw the structures of F and G.
1.5 The condensation reaction above giving G proceeds well. This shows that the pKa of the conjugate acid of piperidine is (mark X in the correct box)

1.6 Identify the structures H to J.
1.7 L (C5H10O5) on reduction with sodium borohydride (NaBH4) gives an optically inactive alditol. Draw the Fischer projection formula of L with correct configuration at all chiral carbons
1.8 One of the chemical syntheses of K involves a series of reactions as given below.

1.9 Degradation studies of K had played an important role in its identification. Alkaline hydrolysis of K with 1 M NaOH at 100oC gave P (C16H19N2NaO7) by losing a mole of B. Further hydrolysis of P by 5M NaOH at 100oC gave Q (C13H22N2O4). Draw structure of P and Q.