Experimental Techniques in Organic Chemistry - Organic Chemistry - Chemistry Previous Year Questions

1

2008 · Chemistry · Organic Chemistry · Experimental Techniques in Organic Chemistry

Chemistry (CY) 2008

The formation of the organic product in the above reaction can be monitored by

A

gas chromatography

B

cyclic voltammetry

C

electron spin resonance

D

fluorescence spectroscopy

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2

2012 · Chemistry · Organic Chemistry · Experimental Techniques in Organic Chemistry

Chemistry (CY) 2012

The ratio of relative intensities of the two molecular ion peaks of methyl bromide (CH₃Br) in the mass spectrum is

A

M⁺ : (M+2)⁺ = 1:3

B

M⁺ : (M+2)⁺ = 3:1

C

M⁺ : (M+2)⁺ = 1:1

D

M⁺ : (M+2)⁺ = 1:2

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3

2013 · Chemistry · Organic Chemistry · Experimental Techniques in Organic Chemistry

Chemistry (CY) 2013

The number of signals that appear in the proton decoupled ¹³C NMR spectrum of benzonitrile (C₆H₅N) is ______.

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4

2013 · Chemistry · Organic Chemistry · Experimental Techniques in Organic Chemistry

Chemistry (CY) 2013

An organic compound Q exhibited the following spectral data: IR: 1760 cm^-1; ¹H NMR: δ (ppm): 7.2 (1H, d, J = 16.0 Hz), 5.1 (1 H, m), 2.1 (3 H, s), 1.8 (3H, d, J = 7.0 Hz); ¹³C NMR: δ (ppm): 170 (carbonyl carbon). Compound Q is

A

B

C

D

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5

2013 · Chemistry · Organic Chemistry · Experimental Techniques in Organic Chemistry

Chemistry (CY) 2013

Match the patterns of the NMR signals given in column I with temperatures given in the column II.
I
(i) Two singlets, for three protons each, at δ 2.87 and 2.97 ppm
(ii) One sharp singlet for six protons at δ 2.92 ppm
(iii) One broad signal for six protons
II
(x) 25 °C
(y) 120 °C
(z) 150 °C

A

(i)-(x); (ii)-(y); (iii)-(z)

B

(i)-(x); (ii)-(z); (iii)-(y)

C

(i)-(z); (ii)-(x); (iii)-(y)

D

(i)-(z); (ii)-(y); (iii)-(x)

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6

2014 · Chemistry · Organic Chemistry · Experimental Techniques in Organic Chemistry

Chemistry (CY) 2014

At room temperature, the number of singlet resonances observed in the ¹H NMR spectrum of Me₃CC(O)NMe₂ (N,N-dimethyl pivalamide) is _____________

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7

2014 · Chemistry · Organic Chemistry · Experimental Techniques in Organic Chemistry

Chemistry (CY) 2014

The set of protons (underlined) in CH₃CH₂CH₂OCH₃ that would exhibit different splitting patterns in high (500 MHz) and low (60 MHz) field ¹H NMR, is

A

CH₃CH₂CH₂OCH₃

B

CH₃CH₂CH₂OCH₃

C

CH₃CH₂CH₂OCH₃

D

CH₃CH₂CH₂OCH₃

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8

2016 · Chemistry · Organic Chemistry · Experimental Techniques in Organic Chemistry

Chemistry (CY) 2016

On reacting 1.55 g of a diol with an excess of methylmagnesium iodide, 1.12 L (corrected to STP) of methane gas is liberated. The molecular mass (g mol⁻¹) of the diol is ________.

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9

2024 · Chemistry · Organic Chemistry · Experimental Techniques in Organic Chemistry

Chemistry (CY) 2024

\(^1H\) NMR spectrum of a mixture containing \(CH_3Br\) (\(x\) mol) and \((CH_3)_3CBr\) (\(y\) mol) shows two singlets at 2.7 ppm and 1.8 ppm, with the relative ratio of 3:1 (integration value), respectively. The value of \(x/y\) is ____.
(rounded off to the nearest integer)

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10

2007 · Chemistry · Organic Chemistry · Experimental Techniques in Organic Chemistry

Chemistry (CY) 2007

Among the isomers of C₁₀H₁₄ shown, the isomer that can be identified uniquely by mass spectrometry alone is

A

P

B

Q

C

R

D

S

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11

2015 · Chemistry · Organic Chemistry · Experimental Techniques in Organic Chemistry

Chemistry (CY) 2015

The mass spectrum of a dihalo compound shows peaks with relative intensities of 1:2:1 corresponding to M, M+2 and M+4 (M is the mass of the molecular ion), respectively. The compound is

A

1,3-dibromo-5-methylbenzene

B

1-bromo-3-chloro-5-methylbenzene

C

1-chloro-3-methyl-5-bromobenzene

D

1-fluoro-3-chloro-5-methylbenzene

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12

2015 · Chemistry · Organic Chemistry · Experimental Techniques in Organic Chemistry

Chemistry (CY) 2015

The tetrapeptide, Ala-Val-Phe-Met, on reaction with Sanger's reagent, followed by hydrolysis gives

A

2,4-dinitrophenylalanine with a thioether side chain

B

2,4-dinitrophenylvaline

C

2,4-dinitrophenylalanine

D

2,4-dinitrophenylphenylalanine

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13

2017 · Chemistry · Organic Chemistry · Experimental Techniques in Organic Chemistry

Chemistry (CY) 2017

The ¹³C NMR spectrum of acetone-d₆ has a signal at 30 ppm as a septet in the intensity ratio

A

1 : 6 : 15 : 20 : 15 : 6 : 1

B

1 : 3 : 6 : 7 : 6 : 3 : 1

C

1 : 2 : 3 : 5 : 3 : 2 : 1

D

1 : 3 : 7 : 10 : 7 : 3 : 1

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14

2018 · Chemistry · Organic Chemistry · Experimental Techniques in Organic Chemistry

Chemistry (CY) 2018

In the electron ionization (EI) mass spectra, methyl hexanoate, methyl heptanoate and methyl octanoate give the same base peak. The m/z value of the base peak is __________.

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15

2020 · Chemistry · Organic Chemistry · Experimental Techniques in Organic Chemistry

Chemistry (CY) 2020

A compound with molecular formula \(C_{10}H_{12}O_2\) showed a strong IR band at \(-1720\) cm\(^{-1}\), a peak at \(m/z\) 122 in the mass spectrum and the following \(^1H\) NMR signals: \(\delta\) 8.1-8.0 (2H, m), 7.6-7.5 (1H, m), 7.5-7.3 (2H, m), 4.3 (2H, t), 1.8 (2H, sextet) and 1.0 (3H, t). The structure of the compound is:

A

Structure A

B

Structure B

C

Structure C

D

Structure D

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16

2021 · Chemistry · Organic Chemistry · Experimental Techniques in Organic Chemistry

Chemistry (CY) 2021

An organic compound exhibits the [M]⁺, [M+2]⁺ and [M+4]⁺ peaks in the intensity ratio 1:2:1 in the mass spectrum, and shows a singlet at δ 7.49 in the ¹H NMR spectrum in CDCl₃. The compound is:

A

1,4-dichlorobenzene

B

1,4-dibromobenzene

C

1,2-dibromobenzene

D

1,2-dichlorobenzene

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