Deduce the structure of a molecule from its 1H NMR spectrum using the number of signals (distinct hydrogen environments), chemical shifts compared with the data booklet table and the integration ratio giving the relative numbers of protons.
Tę umiejętność sprawdza 35 zadań wzorowanych na arkuszach IB z lat 2022–2026.
Sulfapyridine is an antibacterial drug. Its structure is shown below. C11H11N3O2S Mr = 249.32 (i) Deduce the hybridization of the nitrogen atom that is part of a ring. (ii) Describe how the sigma (σ) and pi (π) components of an…
Pentane reacts with bromine, Br2, to form 2-bromopentane. (i) Explain, using equations, the initiation step and two propagation steps for this reaction. (ii) 2-Bromopentane reacts with aqueous sodium hydroxide, NaOH(aq), to form pentan-2-ol,…
(i) Explain why 1,2-dichloroethene, ClCH=CHCl, has two stereoisomers but 1,1-dichloroethene, CH2=CCl2, does not. (ii) State the hybridization of the carbon atoms in propene, CH3CH=CH2. (iii) Predict the number of signals and the relative…
What are the splitting patterns of the signals in the 1H NMR spectrum of ethoxyethane, CH3CH2OCH2CH3? A. A doublet and a quartet B. A triplet and a quartet C. A singlet and a triplet D. A doublet and a triplet
Which option describes the 1H NMR spectrum of the compound shown? A. 2 signals, relative areas 3:5 B. 3 signals, relative areas 3:4:1 C. 5 signals, relative areas 3:2:1:1:1 D. 4 signals, relative areas 3:2:2:1
The mass spectrum of carbonyl dibromide is shown below. Bromine has two isotopes, and , of almost equal abundance. (i) Explain the origin of the peaks that appear at m/z values smaller than those of the molecular ion. (ii) Deduce…
The compound X shown below occurs naturally in cocoa and coffee and is used as a flavouring agent. (i) State the name of the functional group found in compound X. (ii) Deduce the IUPAC name of X. (iii) Deduce how many signals the NMR spectrum of X…
The NMR spectrum of an alcohol with molecular formula C5H11OH shows four signals with relative areas 6 : 4 : 1 : 1. Which alcohol is it? A. Pentan-1-ol B. Pentan-3-ol C. 2-methylbutan-2-ol D. 2,2-dimethylpropan-1-ol
Which oxygen-containing compound gives this low-resolution NMR spectrum? A. Propanone B. Methyl ethanoate C. Propanoic acid D. Propan-2-ol
In the mass spectrum of Y, the molecular ion peak appears at m/z 88. (i) Y contains no multiple carbon–carbon bonds and no rings. Deduce its molecular formula. Use section 7 of the data booklet. Shown below is the high-resolution NMR spectrum of Y,…
Which is the low-resolution NMR spectrum of methyl methanoate, HCOOCH3? A. Spectrum A B. Spectrum B C. Spectrum C D. Spectrum D
(i) Draw the structural formula of 2-chloropentane and that of the structural isomer in which the chlorine atom is attached to a tertiary carbon atom. (ii) Only one of the two isomers drawn in (c)(i) is chiral. Draw stereochemical formulas showing its two…
The NMR spectra of four compounds are described below. Which is the spectrum of propanone, CH3COCH3? Use section 21 of the data booklet. A. one singlet at 2.2 ppm B. a quartet at 2.4 ppm and a triplet at 1.0 ppm, with relative areas 2 : 3…
A sample is known to be either propan-1-ol or propanoic acid. Its 1H NMR spectrum is shown. (i) Deduce, giving a reason, whether the sample is propan-1-ol or propanoic acid. Use section 21 of the data booklet. (ii) Predict, giving a reason, the splitting…
Compounds M and N both contain a 4-methoxyphenyl group, shown at the left of each structure. Their side chains are −CH2CH2COOH in M and −C(CH3)2OH in N. Predict the number of signals and the relative areas you would expect in the 1H NMR…
What are the number of signals and the splitting of these signals in the 1H NMR spectrum of ethoxyethane, CH3CH2OCH2CH3? A. 1 signal, a singlet B. 2 signals, a triplet and a quartet C. 2 signals, two triplets D. 2 signals, a doublet and a quartet
(i) Predict the number of signals in the 1H NMR spectrum of 3-methylbutanoic acid and the ratio of their areas. (ii) Predict the splitting pattern of the signal due to the two hydrogen atoms of the CH2 group. (iii) State one reason why…
Which compound gives this 1H NMR spectrum? A. Diethyl ether, CH3CH2OCH2CH3 B. Methyl propanoate, CH3CH2COOCH3 C. Butanone, CH3COCH2CH3 D. Ethyl ethanoate, CH3COOCH2CH3
Propanoic acid reacts with methanol to produce an ester. (i) Draw the full structural formula of the organic product. (ii) Predict the number of signals, and their splitting patterns, in the 1H NMR spectrum of this ester. (iii) The chemical shifts in…
The skeletal formulae of two esters with the molecular formula C4H8O2 are shown. (i) Deduce the number of signals you would expect in the 1H NMR spectrum of each compound. (ii) Outline why infrared spectroscopy is not used to differentiate between…
Which compound produces the 1H NMR spectrum shown? The areas under the two signals are in the ratio 1 : 1. A. CH3COCH3 B. CH3COOCH3 C. CH3COOCH2CH3 D. CH3OCH3
Spectra can be used to monitor the conversion of ethanoic acid into the ester. (i) State one similarity and one difference between the infrared (IR) spectra of ethanoic acid and of the ester in the 1500–3500 cm−1 region. Use section 20 of the…
The conversion of propanoic acid into the ester can be followed by changes in spectra. (i) Compare the infrared (IR) spectra of propanoic acid and of the ester between 1500 and 3500 cm−1 by stating one feature they share and one feature in which…
Deduce which of aspirin and camphor gives 1H NMR signals with chemical shifts between 6.9 and 9.0 ppm, and give a reason. Use section 21 of the data booklet.
Ibuprofen and glyceryl trinitrate (GTN) are two drugs with the structures shown. Deduce, giving a reason, whether the 1H NMR spectrum of ibuprofen or of GTN has signals with chemical shifts in the 6.9–9.0 ppm region. Use section 21 of the data booklet.
Which compound produces the high resolution 1H NMR spectrum shown? A. Propanone B. Butanal C. Butanone D. Pentan-3-one
Use section 21 of the data booklet. The high resolution 1H NMR spectrum of an unknown compound is shown. Which compound is it? A. Butane B. Butanone C. Ethoxyethane D. Pentan-3-one
Benzene reacts with bromine in the presence of an iron(III) bromide catalyst to form bromobenzene. The reaction is an electrophilic substitution in which the electrophile is Br+. (i) Draw the structural formula of the carbocation intermediate formed as…
(i) Write the equation for the reaction between hex-3-ene and hydrogen bromide. (ii) State the type of reaction in (i). (iii) Suggest two differences between the NMR spectra of hex-3-ene and of the organic product in (i). Use section 21 of the data…
Which compound produces the following 1H NMR spectrum? A. Butanal B. Butanone C. 2-Methylpropanal D. 2-Methylpropan-1-ol
How many different signals does the 1H NMR spectrum of this compound show? A. 1 B. 2 C. 3 D. 4
Equimolar samples of the following compounds are dissolved in a solvent that gives no 1H NMR signal. Which compound gives the signal with the greatest area in its 1H NMR spectrum? A. C6H6 B. CH3CH2CH2CH2CH2CH2CH2CH3 C. (CH3)4C D.…
(i) Deduce the number of signals and the ratio of the areas under the signals in the NMR spectrum of 2-bromopentane. Number of signals: Ratio of areas: (ii) Identify the splitting pattern of the signal of (A) the hydrogen atoms of the methyl group…
What information about pentan-2-one, CH3COCH2CH2CH3, can be obtained from mass spectrometry (MS), infrared (IR) spectroscopy and 1H NMR spectroscopy? A. MS: the compound contains a carbonyl group; IR: the molar mass is 86 g mol−1;…
Which compound gives the low-resolution 1H NMR spectrum shown? A. Ethanal B. Ethanoic acid C. Methyl ethanoate D. Propanone
Zapisujemy na Twoim urządzeniu to, bez czego serwis nie działa, np. zalogowanie. Plików analitycznych użyjemy tylko za Twoją zgodą. Szczegóły w polityce prywatności.