3 1H NMR

 

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3.15 Nmr Page 1 - 2, 4

Oxford Textbook Pages : 486 - 493

CGP Revision Guide Pages : 195 - 197

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Show Specification Ref : 3.3.15

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Question 1 / 5

AQA Jan 2011 Paper 4 Q5 do not write outside the box atenolol is an example of the type of medicine called a beta blocker these medicines are used to lower blood pressure by slowing the heart rate the structure of atenolol is shown below ch h n oh ch ch ch p ch ch ch q a give the name of each of the circled functional groups labelled j and k on the structure of atenolol shown above functional group labelled j functional group labelled k marks b the h n m r spectrum of atenolol was recorded one of the peaks in the h n m r spectrum is produced by the ch group labelled p in the structure of atenolol use table on the data sheet to suggest a range of values for this peak name the splitting pattern of this peak range of values name of splitting pattern marks c n m r spectra are recorded using samples in solution the h n m r spectrum was recorded using a solution of atenolol in cdcl c i suggest why cdcl and not chcl was used as the solvent mark c ii suggest why cdcl is a more effective solvent than ccl for polar molecules such as atenolol mark wmp jan chem do not write outside the box d the c n m r spectrum of atenolol was also recorded use the structure of atenolol given to deduce the total number of peaks in the c n m r spectrum of atenolol e mark part of the c n m r spectrum of atenolol is shown below use this spectrum and table on the data sheet where appropriate to answer the questions which follow ppm e i give the formula of the compound that is used as a standard and produces the peak at ppm in the spectrum mark e ii one of the peaks in the c n m r spectrum above is produced by the ch group labelled q in the structure of atenolol identify this peak in the spectrum by stating its value mark e iii there are three ch groups in the structure of atenolol one of these ch groups produces the peak at in the c n m r spectrum above draw a circle around this ch group in the structure of atenolol shown below ch ch oh ch ch ch ch ch h n question continues on the next page mark turn over wmp jan chem do not write outside the box f atenolol is produced industrially as a racemate an equimolar mixture of two enantiomers by reduction of a ketone both enantiomers are able to lower blood pressure however recent research has shown that one enantiomer is preferred in medicines f i suggest a reducing agent that could reduce a ketone to form atenolol mark f ii draw a circle around the asymmetric carbon atom in the structure of atenolol shown below ch ch oh ch ch ch ch ch h n mark f iii suggest how you could show that the atenolol produced by reduction of a ketone was a racemate and not a single enantiomer marks f iv suggest one advantage and one disadvantage of using a racemate rather than a single enantiomer in medicines advantage disadvantage marks wmp jan chem turn over for the next question do not write on this page answer in the spaces provided turn over wmp jan chem
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Question 2 / 5

AQA Jan 2012 Paper 4 Q6 do not write outside the box a compound x c h o was analysed by infrared spectroscopy and by proton nuclear magnetic resonance spectroscopy the infrared spectrum of x is shown below use table on the data sheet to help you answer the question transmittance wavenumber cm identify the functional group that causes the absorption at cm in the spectrum mark wmp jan chem b the proton n m r spectrum of x consists of singlet peaks do not write outside the box the table below gives the chemical shift for each of these peaks together with their integration values ppm integration value use table on the data sheet to help you answer the following questions use the chemical shift and the integration data to show what can be deduced about the structure of x from the presence of the following in its proton n m r spectrum b i the peak at mark b ii the peak at mark b iii the peak at mark b iv deduce the structure of x c h o mark turn over wmp jan chem
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Question 3 / 5

AQA Jan 2013 Paper 4 Q5 do not write outside the box a this question concerns isomers of c h o and how they can be distinguished using n m r spectroscopy the non toxic inert substance tms is used as a standard in recording both h and c n m r spectra a i give two other reasons why tms is used as a standard in recording n m r spectra reason reason marks a ii give the structural formula of tms b the proton n m r spectrum of compound p c h o is represented in figure figure mark ppm the integration trace gave information about the five peaks as shown in figure figure ppm integration ratio wmp jan chem do not write outside the box b i use table on the data sheet figure and figure to deduce the structural fragment that leads to the peak at b ii use table on the data sheet figure and figure to deduce the structural fragment that leads to the peaks at and mark b iii use table on the data sheet figure and figure to deduce the structural fragment that leads to the peaks at and mark b iv deduce the structure of p question continues on the next page mark mark turn over wmp jan chem do not write outside the box c these questions are about different isomers of p c h o c i draw the structures of the two esters that both have only two peaks in their proton n m r spectra these peaks both have an integration ratio of ester ester c ii draw the structure of an optically active carboxylic acid with five peaks in its c n m r spectrum marks mark c iii draw the structure of a cyclic compound that has only two peaks in its c n m r spectrum and has no absorption for c o in its infrared spectrum mark wmp jan chem turn over for the next question do not write on this page answer in the spaces provided turn over wmp jan chem
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Question 4 / 5

AQA Jun 2011 Paper 4 Q5 do not write outside the box items softened with plasticisers have become an essential part of our modern society compound s shown below is commonly known as phthalic acid esters of phthalic acid are called phthalates and are used as plasticisers to soften polymers such as pvc poly chloroethene cooh cooh a give the iupac name for phthalic acid mark b draw the displayed formula of the repeating unit of poly chloroethene mark question continues on the next page turn over wmp jun chem do not write outside the box c the ester diethyl phthalate dep is used in food packaging and in cosmetics c i complete the following equation showing the formation of dep from phthalic anhydride cooch ch cooch ch dep marks c ii deduce the number of peaks in the c n m r spectrum of dep mark c iii one of the peaks in the c n m r spectrum of dep is at ppm table on the data sheet can be used to identify a type of carbon atom responsible for this peak draw a circle around one carbon atom of this type in the structure below cooch ch cooch ch d the mass spectrum of dep includes major peaks at m z the molecular ion and at m z write an equation to show the fragmentation of the molecular ion to form the fragment that causes the peak at m z mark marks wmp jun chem do not write outside the box e because of their many uses phthalates have been tested for possible adverse effects to humans and to the environment the european council for plasticisers and intermediates is an organisation that represents the manufacturers of plasticisers the text below is taken from a document written by the organisation research demonstrates that phthalates at current and foreseeable exposure levels do not pose a risk to human health or to the environment experimental evidence shows that phthalates are readily biodegradable and do not persist for long in the environment e i hydrolysis of dep in an excess of water was found to follow first order kinetics write a rate equation for this hydrolysis reaction using dep to represent the ester mark e ii suggest what needs to be done so that the public could feel confident that the research quoted above is reliable marks extra space turn over wmp jun chem
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Question 5 / 5

AQA Jun 2016 Paper 4 Q9 b draw the structure of compound s for each of steps and give a reagent and one condition other than heat do not write outside the box marks turn over wmp jun chem do not write outside the box compound r contains carbon and hydrogen by mass the remainder is oxygen the mass spectrum of r contains a molecular ion peak at m z a use these data to show that the molecular formula of r is c h o marks b the infrared spectrum of r c h o is shown in figure figure transmittance wavenumber cm the proton n m r spectrum of r contains five peaks the chemical shift values integration ratios and splitting patterns of these peaks are given in table chemical shift ppm integration ratio table splitting patterns triplet singlet singlet triplet singlet wmp jun chem
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