NUCLEAR MAGNETIC RESONANCE SPECTROSCPY A guide for A

NUCLEAR MAGNETIC RESONANCE SPECTROSCPY A guide for A level students KNOCKHARDY PUBLISHING 2008 SPECIFICATIONS KNOCKHARDY PUBLISHING NMR SPECTROSCOPY INTRODUCTION This Powerpoint show is one of several produced to help students understand selected topics at AS and A2 level Chemistry. It is based on the requirements of the AQA and OCR specifications but is suitable for other examination boards. Individual students may use the material at home for revision purposes or it may be used for classroom teaching if an interactive white board is available. Accompanying notes on this, and the full range of AS and A2 topics, are available

from the KNOCKHARDY SCIENCE WEBSITE at... www.knockhardy.org.uk/sci.htm Navigation is achieved by... either clicking on the grey arrows at the foot of each page or using the left and right arrow keys on the keyboard NMR SPECTROSCOPY CONTENTS Prior knowledge What is nmr? Origin of spectra Tetramethylsilane Chemical shift Resolution

Multiplicity - splitting patterns Integration OH signals and the use of D2O Working out spectra Questions on proton nmr Carbon-13 nmr NMR SPECTROSCOPY Before you start it would be helpful to know the names and structures of organic functional groups find the structures of isomers given the molecular formula PREVIEW WHAT IS NMR AND WHAT DOES AN NMR SPECTRUM TELL YOU? Proton nuclear magnetic resonance spectroscopy provides... information about the hydrogen atoms in molecules How does it work? involves the interaction of materials with the LOW ENERGY RADIO WAVES It provides the information by... spinning a sample of the compound in a magnetic field

hydrogen atoms in different environments respond differently to the field each different environment of hydrogen produces a signal in a different position the area under each peak / signal is proportional to the number of hydrogens signal can be split according to how many Hs are on adjacent atoms NMR SPECTROSCOPY ORIGIN OF SPECTRA All nuclei possess charge and mass. Those with either an odd mass number or an odd atomic number also possess spin. This means they have angular momentum. POSSESS SPIN 1 H 1 2 H 1 DON T POSSESS SPIN

12 C 6 A nucleus without spin cannot be detected by nuclear magnetic resonance spectroscopy. ENERGY A spinning nucleus such as 1H behaves as a spinning charge and generates a magnetic field. It can be likened to a bar magnet. When it is placed in an externally applied field it can align with, or against, the field. The energy difference between the two states () depends on the applied field.

13 C 6 19 F 9 31 P 15 aligned against the field h aligned with the field NMR SPECTROMETERS

The sample is spun round in the field of a large electromagnet and a radio-frequency (RF) field is applied. The magnetic field is increased and the excitation or flipping of nuclei from one orientation to another is detected as an induced voltage resulting from the absorption of energy from the RF field. THE BASIC ELEMENTS OF AN NMR SPECTROMETER RADIOFREQUENCY OSCILLATOR An nmr spectrum is the plot of the induced voltage against the sweep of the field. The area under a peak is proportional to the number of nuclei flipping Not all hydrogen nuclei absorb energy at the same field strength at a given frequency; the field strength required depends on the environment of the hydrogen. By observing the field strength at which protons absorb energy, one can deduce something about the structure of a molecule. NMR SPECTROSCOPY

INTERPRETATION OF SPECTRA NMR spectra provide information about the structure of organic molecules from the ... number of different signals in the spectrum position of the signals (chemical shift) intensity of the signals splitting pattern of the signals NMR SPECTROSCOPY INTERPRETATION OF SPECTRA NMR spectra provide information about the structure of organic molecules from the ...

number of different signals in the spectrum position of the signals (chemical shift) intensity of the signals splitting pattern of the signals NMR SPECTROSCOPY INTERPRETATION OF SPECTRA NMR spectra provide information about the structure of organic molecules from the ... number of different signals in the spectrum position of the signals (chemical shift) intensity of the signals splitting pattern of the signals

OBTAINING SPECTRA a liquid sample is placed in a tube which spins in a magnetic field solids are dissolved in deuterated solvents (CDCl3) or solvents without Hs (CCl4 ) [solvents with hydrogen atoms in them will produce peaks in the spectrum] TMS, tetramethylsilane, (CH3)4Si, is added to provide a reference signal when the spectrum is run, it can be integrated to find the relative peak areas spectrometers are now linked to computers to analyse data and store information TETRAMETHYLSILANE - TMS PROVIDES THE REFERENCE SIGNAL non-toxic liquid - SAFE TO USE inert - DOESNT REACT WITH COMPOUND BEING ANALYSED has a low boiling point - CAN BE DISTILLED OFF AND USED AGAIN all the hydrogen atoms are chemically equivalent - PRODUCES A SINGLE PEAK twelve hydrogens so it produces an intense peak - DONT NEED TO USE MUCH signal is outside the range shown by most protons - WONT OBSCURE MAIN SIGNALS given the chemical shift of = 0 the position of all other signals is measured relative to TMS

The molecule contains four methyl groups attached to a silicon atom in a tetrahedral arrangement. All the hydrogen atoms are chemically equivalent. CHEMICAL SHIFT each proton type is said to be chemically shifted relative to a standard (usually TMS) the chemical shift is the difference between the field strength at which it absorbs and the field strength at which TMS protons absorb the delta () scale is widely used as a means of reporting chemical shifts = Observed chemical shift (Hz) x 106

ppm (parts per million) Spectrometer frequency (Hz) the chemical shift of a proton is constant under the same conditions (solvent, temperature) the TMS peak is assigned a value of ZERO ( = 0.00) all peaks of a sample under study are related to it and reported in parts per million Hs near to an electronegative species are shifted downfield to higher values H Approximate chemical shifts - C-X ROH -CHO

-COOH 13 12 11 -C=CH10 9 The actual values depend on the environment - C-H 8

7 6 5 TMS 4 DOWNFIELD - deshielding 3 2 1 0

LOW RESOLUTION - HIGH RESOLUTION low resolution nmr gives 1 peak for each environmentally different group of protons high resolution gives more complex signals - doublets, triplets, quartets, multiplets the signal produced indicates the number of protons on adjacent carbon atoms LOW RESOLUTION SPECTRUM OF 1-BROMOPROPANE LOW RESOLUTION - HIGH RESOLUTION low resolution nmr gives 1 peak for each environmentally different group of protons high resolution gives more complex signals - doublets, triplets, quartets, multiplets the signal produced indicates the number of protons on adjacent carbon atoms HIGH RESOLUTION SPECTRUM OF 1-BROMOPROPANE The broad peaks are split into sharper signals

The splitting pattern depends on the number of hydrogen atoms on adjacent atoms MULTIPLICITY (Spin-spin splitting) low resolution nmr gives 1 peak for each environmentally different group of protons high resolution gives more complex signals - doublets, triplets, quartets, multiplets the signal produced indicates the number of protons on adjacent carbon atoms Number of peaks = number of chemically different Hs on adjacent atoms + 1 1 neighbouring H 2 peaks doublet 1:1 2 neighbouring Hs 3 peaks triplet 1:2:1 3 neighbouring Hs

4 peaks quartet 1:3:3:1 4 neighbouring Hs 5 peaks quintet 1:4:6:4:1 Signals for the H in an O-H bond are unaffected by hydrogens on adjacent atoms - get a singlet MULTIPLICITY (Spin-spin splitting) low resolution nmr gives 1 peak for each environmentally different group of protons high resolution gives more complex signals - doublets, triplets, quartets, multiplets the signal produced indicates the number of protons on adjacent carbon atoms Number of peaks = number of chemically different Hs on adjacent atoms + 1 0 neighbouring Hs 1 neighbouring H

2 neighbouring Hs 3 neighbouring Hs 4 neighbouring Hs signal isnt split signal split into 1 peak 2 peaks 3 peaks 4 peaks 5 peaks singlet doublet ratio = 1:1 triplet 1:2:1 quartet 1:3:3:1 quintet

1:4:6:4:1 MULTIPLICITY (Spin-spin splitting) low resolution nmr gives 1 peak for each environmentally different group of protons high resolution gives more complex signals - doublets, triplets, quartets, multiplets the signal produced indicates the number of protons on adjacent carbon atoms Number of peaks = number of chemically different Hs on adjacent atoms + 1 0 neighbouring Hs 1 neighbouring H 2 neighbouring Hs 3 neighbouring Hs 4 neighbouring Hs signal isnt split signal split into 1 peak 2 peaks 3 peaks 4 peaks

5 peaks singlet doublet ratio = 1:1 triplet 1:2:1 quartet 1:3:3:1 quintet 1:4:6:4:1 PASCALS TRIANGLE 1 It is interesting to note the relationship between the successive peak ratios. It follows the pattern found in Pascals triangle. 1 1

1 Each number in the series is the sum of the two numbers above it in the triangle What would be the pattern for 6 neighbouring hydrogens? PRESS THE SPACE BAR FOR THE ANSWER 1 1 2 3 4 1 3 6

1 4 1 1 5 10 10 5 1 1 6 15 20 15 6 1 MULTIPLICITY (Spin-spin splitting) Splitting patterns are worked out by considering the effect adjacent, chemically different protons have on another signal in a given environment. The spin of the proton producing the signal is affected by each of the two forms of the adjacent proton. One orientation augments/enhances its field and the other opposes/reduces it. This is done by calculating the various possible combinations of alignment of adjacent protons. HOWEVER Signals for the H in an O-H bond are not affected by hydrogens on adjacent atoms so are not split

MULTIPLICITY (Spin-spin splitting) ANALOGY Imagine you had an opinion on something. If nobody influenced you, your opinion would be the same. However if another person had a view on the topic, they would either agree or disagree with you. Their ideas would either enhance what you thought or diminish it. There would be two possibilities of equal chance. If there were two people offering views they could either be both for it (1 possibility) , both against (1 possibility) or one could be in favour and the other against (2 possibilities). There would be three possibilities of relative chance 1:2:1 CONTENTS CONTENTS FOR AGAINST

MULTIPLICITY (Spin-spin splitting) O adjacent Hs There is no effect MULTIPLICITY (Spin-spin splitting) O adjacent Hs There is no effect 1 adjacent H can be aligned either with or against the field there are only two equally probable possibilities the signal is split into 2 peaks of equal intensity MULTIPLICITY (Spin-spin splitting) O adjacent Hs There is no effect 1 adjacent H can be aligned either with or against the field there are only two equally probable possibilities the signal is split into 2 peaks of equal intensity

2 adjacent Hs more possible combinations get 3 peaks in the ratio 1 : 2 : 1 MULTIPLICITY (Spin-spin splitting) O adjacent Hs There is no effect 1 adjacent H can be aligned either with or against the field there are only two equally probable possibilities the signal is split into 2 peaks of equal intensity 2 adjacent Hs more possible combinations get 3 peaks in the ratio 1 : 2 : 1 3 adjacent Hs even more possible combinations get 4 peaks in the ratio 1 : 3 : 3 : 1

EXPLAIN THE THEORY BEHIND THE SPLITTING PATTERN FOR 4 ADJACENT Hs MULTIPLICITY (Spin-spin splitting) 4 adjacent Hs gives 5 peaks in the ratio 1 : 4 : 6 : 4 : 1 INTEGRATION the area under a signal is proportional to the number of hydrogen atoms present an integration device scans the area under the peaks lines on the spectrum show the relative abundance of each hydrogen type (old method) computers now display the information as numerical data By measuring the distances between the integration lines one can work out the simple ratio between the various types of hydrogen. before integration

NOTICE THAT THE O-H SIGNAL IS ONLY A SINGLET (see later for an explanation of this) after integration INTEGRATION Measure the distance between the top and bottom lines. Compare the heights from each signal and make them into a simple ratio. Computers now do the integration automatically

HOW TO WORK OUT THE SIMPLE RATIOS (OLD METHOD) Measure how much each integration line rises as it goes of a set of signals Compare the relative values and work out the simple ratio between them In the above spectrum the rises are in the ratio... 1:2:3 IMPORTANT: It doesnt provide the actual number of Hs in each environment, just the ratio O-H bonds and splitting patterns The signal due to the hydroxyl (OH) hydrogen is a singlet ... there is no splitting Hs on OH groups do not couple with adjacent hydrogen atoms Arises because the H on the OH, rapidly exchanges with protons on other molecules (such as water or acids) and is not attached to any particular oxygen long enough to register a splitting signal. O-H bonds and splitting patterns The signal due to the hydroxyl (OH) hydrogen is a singlet ... there is no splitting Hs on OH groups do not couple with adjacent hydrogen atoms Arises because the H on the OH, rapidly exchanges with protons on other molecules (such as water or acids) and is not attached to any particular oxygen long enough to register a splitting signal.

OH hydrogens are always seen as a singlet ... there is no splitting This is a quartet despite the fact that there are 4 Hs on adjacent atoms the H on the OH doesnt couple O-H bonds and the D2O shake As has been pointed out, the signal due to the hydroxyl (OH) hydrogen is a singlet. It is possible to identify which signal is caused by the H of an O-H group by doing a D2O shake. A small amount of deuterium oxide D2O, a form of water, is added to the sample and the spectrum is re-run. Any signal due to O-H proton disappears. The H in the O-H bond changes places with a deuterium atom, 2H or D, from D2O Deuterium doesnt exhibit nuclear magnetic resonance under the conditions used for proton nmr so the signal is removed to another part of the spectrum. . O-H bonds and the D2O shake As has been pointed out, the signal due to the hydroxyl (OH) hydrogen is a singlet. It is possible to identify which signal is caused by the H of an O-H group by doing a D2O shake. A small amount of deuterium oxide D2O, a form of water, is added to the

sample and the spectrum is re-run. Any signal due to O-H proton disappears. The H in the O-H bond changes places with a deuterium atom, 2H or D, from D2O Deuterium doesnt exhibit nuclear magnetic resonance under the conditions used for proton nmr so the signal is removed to another part of the spectrum. before shaking with D2O O-H bonds and the D2O shake As has been pointed out, the signal due to the hydroxyl (OH) hydrogen is a singlet. It is possible to identify which signal is caused by the H of an O-H group by doing a D2O shake. A small amount of deuterium oxide D2O, a form of water, is added to the sample and the spectrum is re-run. Any signal due to O-H proton disappears. The H in the O-H bond changes places with a deuterium atom, 2H or D, from D2O Deuterium doesnt exhibit nuclear magnetic resonance under the conditions used for proton nmr so the signal is removed to another part of the spectrum. . before shaking with D2O after shaking with D2O

HHatoms atomsattached attachedto tothe theNNin inamines aminesalso alsointerchange interchangewith withdeuterium deuterium NMR SPECTROSCOPY When is a hydrogen chemically different? TWO SIGNALS Quartet and triplet :- ratio of peak areas = 3 : 2 1 2

3 BUTANE 4 Carbons 1 & 4 are the similar and so are carbons 2 & 3 so there are only two different chemical environments. The signal for Hs on carbon 2 is a quartet - you ignore the two neighbours on carbon 3 because they are chemically identical. NMR SPECTROSCOPY When is a hydrogen chemically different? TWO SIGNALS Quartet and triplet :- ratio of peak areas = 3 : 2 1 2

3 4 BUTANE Carbons 1 & 4 are the similar and so are carbons 2 & 3 so there are only two different chemical environments. The signal for Hs on carbon 2 is a quartet - you ignore the two neighbours on carbon 3 because they are chemically identical. TWO SIGNALS both singlets :- ratio of peak areas = 2 : 1 ETHANE-1,2-DIOL Hydrogens on OH groups only give singlets. The signal for Hs on each carbon are not split, because - Hs on the neighbouring carbon are chemically

identical... and - Hs on adjacent OH groups do not couple. NMR SPECTROSCOPY - SUMMARY An nmr spectrum provides several types of information :number of signal groups tells you chemical shift peak area (integration) multiplicity the number of different proton environments the general environment of the protons the number of protons in each environment how many protons are on adjacent atoms In many cases this information is sufficient to deduce the structure of an organic molecule but other forms of spectroscopy are used in conjunction with nmr. NMR SPECTROSCOPY HOW TO WORK OUT AN NMR SPECTRUM 1.

2. 3. 4. Get the formula of the compound Draw out the structure Go to each atom in turn and ask the census questions Work out what the spectrum would look like ... signals due to Hs nearer electronegative atoms (Cl,Br,O) are shifted downfield to higher values THE THEBASIC BASICCENSUS CENSUS Ask Askeach eachhydrogen hydrogenatom atomto... to...

- -describe the position of describe the position ofthe theatom atomon onwhich whichititlives lives - -say sayhow howmany manyhydrogen hydrogenatoms atomslive liveon onthat thatatom atom

- -say sayhow howmany manychemically chemicallydifferent differenthydrogen hydrogenatoms atomslive live on onadjacent adjacentatoms atoms BUT, BUT,REMEMBER REMEMBERTHAT THAT HHatoms atomson onOH

OHgroups groups - - ONLY ONLYPRODUCE PRODUCEONE ONEPEAK PEAK - - DONT DONTCOUNT COUNTAS ASAANEIGHBOUR NEIGHBOUR NMR SPECTROSCOPY CENSUS CENSUSQUESTIONS QUESTIONS - -describe describewhere whereeach eachhydrogen

hydrogenlives lives - -say how many hydrogens live on say how many hydrogens live onthat thatatom atom - -say sayhow howmany manychemically chemicallydifferent differenthydrogen hydrogen atoms live

on adjacent atoms atoms live on adjacent atoms 1 2 3 1-BROMOPROPANE ATOM UNIQUE DESCRIPTION OF THE POSITION OF THE HYDROGEN ATOMS HS ON THE ATOM

CHEMICALLY DIFFERENT HS ON ADJACENT ATOMS SIGNAL SPLIT INTO 1 On an end carbon, two away from the carbon with the bromine atom on it 3 2 2+1 = 3 2

On a carbon atom second from the end and one away from the carbon with the bromine atom 2 3+2 = 5 5+1 = 6 3 On an end carbon atom which also has the bromine atom on it 2 2

2+1 = 3 Spectrum of 1-bromopropane CHEMICAL SHIFTS 1 2 3 3 environments = 3 signals Triplet Sextet Triplet = 3.4 = 1.9 = 1.0

Signal for Hs on carbon 3 is shifted furthest downfield from TMS due to proximity of the electronegative halogen TMS 5 4 3 2 1 0

Spectrum of 1-bromopropane INTEGRATION 1 2 3 Area ratio from relative heights of integration lines = 2 : 2 : 3 Carbon 1 Carbon 2 Carbon 3 2

3 TMS 3 2 2 2 5 4 3 2 1

0 Spectrum of 1-bromopropane SPLITTING 1 1 2 3 SPLITTING PATTERN Carbon 1 Chemically different hydrogen atoms on adjacent atoms = 2 TMS

2+1 =3 The signal will be a TRIPLET 5 4 3 2 1 0 Spectrum of 1-bromopropane

SPLITTING 2 1 2 3 SPLITTING PATTERN Carbon 2 TMS Chemically different hydrogen atoms on adjacent atoms = 5 5+1 =6 The signal will be a SEXTET 5

4 3 2 1 0 Spectrum of 1-bromopropane SPLITTING 3 1 2

3 SPLITTING PATTERN Carbon 3 TMS Chemically different hydrogen atoms on adjacent atoms = 2 2+1 =3 The signal will be a TRIPLET 5 4 3 2

The signal is shifted furthest away (downfield) from TMS as the hydrogen atoms are nearest the electronegative bromine atom. 1 0 Spectrum of 1-bromopropane SPLITTING 3 1 2 2 1

3 3 environments = 3 signals 1 Triplet = 1.0 2 Sextet = 1.9 3 Triplet = 3.4 3 Hs 2 Hs 2 Hs TMS Signal for Hs on carbon 3 is shifted furthest downfield from TMS due to proximity of the electronegative halogen 5

4 3 2 1 0 Spectrum of 1-bromopropane 1 2 3

TMS 4 SUMMARY Peaks Shift Splitting Integration 3 2 1 0

Three different signals as there are three chemically different protons. Signals are shifted away from TMS signal, are nearer to the halogen. Signals include a triplet ( = 1.0) sextet ( = 1.8) triplet ( = 3.4) The integration lines show that the ratio of protons is 2:2:3 The signals due to the protons attached to carbon ... C1 triplet C2 sextet C3 triplet ( = 1.0) ( = 1.8) ( = 3.4) coupled to the two protons on carbon C2 coupled to five protons on carbons C1 and C3 coupled to the two protons on carbon C2 ( 2+1 = 3 )

( 5+1 = 6 ) ( 2+1 = 3 ) NMR SPECTROSCOPY SUPPLEMENTARY QUESTIONS 1. Why is proton nmr more useful for the investigation of organic compounds ? 2. What other nucleus found in organic compounds is investigated using nmr ? 3. What compound is used as the internal reference for proton nmr chemical shifts ? How many peaks does it produce and at what delta () value does it appear ? 4. What uses have been made of nuclear magnetic resonance in other scientific areas ? Supplementary Questions - Answers SEE NEXT FORhydrogen ANSWERS 1. Because organic compounds tend PAGE to contain atoms. 2. Carbon 13

3. Tetramethylsilane (TMS) gives a strong single peak at = 0 4. Magnetic resonance imaging in body scanners NMR SPECTROSCOPY SUPPLEMENTARY QUESTIONS 1. Why is proton nmr more useful for the investigation of organic compounds ? 2. What other nucleus found in organic compounds is investigated using nmr ? 3. What compound is used as the internal reference for proton nmr chemical shifts ? How many peaks does it produce and at what delta () value does it appear ? 4. What uses have been made of nuclear magnetic resonance in other scientific areas ? Supplementary Questions - Answers 1. Because organic compounds tend to contain hydrogen atoms. 2. Carbon 13 3. Tetramethylsilane (TMS) gives a strong single peak at = 0 4. Magnetic resonance imaging in body scanners WHAT IS IT! C2H5Br

WHAT IS IT! C2H3Br3 WHAT IS IT! C2H4Br2 WHAT IS IT! C6H12 WHAT IS IT! C2H4O2 WHAT IS IT! C4H8O2

WHAT IS IT! C3H6O WHAT IS IT! C3H6O WHAT IS IT! C4H8O WHAT IS IT! C8H16O2 WHAT IS IT! C11H16

WHAT IS IT! C8H10 WHAT IS IT! C8H10 WHAT IS IT! C9H12 WHAT IS IT! C6H10O3 WHAT IS IT! C4H8Br2

CARBON-13 NMR SPECTROSCOPY CARBON-13 NMR SPECTROSCOPY After hydrogen, the most useful atom providing information is carbon-13. Natural carbon contains about 1% of this isotope so the instruments for its detection need to be sensitive and spectra will take longer to record. Only the chemical shift is important as each spectrum gives only single lines for each chemically equivalent carbon. CARBON-13 NMR SPECTROSCOPY After hydrogen, the most useful atom providing information is carbon-13. Natural carbon contains about 1% of this isotope so the instruments for its detection need to be sensitive and spectra will take longer to record. Only the chemical shift is important as each spectrum gives only single lines for each chemically equivalent carbon. Environment C - C (alkanes)

C - C=O C - Cl or C - Br C - N (amines) C - OH C = C (alkenes) aromatic Cs (benzene rings) C=O (esters, acids, amides) C=O (aldehydes, ketones) Chemical shift / 10 - 35 10 - 35 30 - 70 35 - 65 50 - 65 115 - 140 125 - 150 160 - 185 190 220

Carbon-13 nmr has wide applications in the study of natural products, biological molecules and polymers. CARBON-13 NMR SPECTRA Isomers of C3H7Br H H H H Br H HCCCBr HCCCH H H H H H H 3 peaks

all three carbons are different 2 peaks the two outer carbons are similar CARBON-13 NMR SPECTRA Isomers of C3H7Br H H H H Br H HCCCBr HCCCH H H H H H H

3 peaks all three carbons are different 2 peaks the two outer carbons are similar Ethanol C2H5OH H COH H H H H C C OH

H H H HC H This is where the proton nmr spectrum of ethanol would be on the same scale. CARBON-13 NMR SPECTRA The carbon-13 spectrum of 2-methylbutane (CH3)2CHCH2CH3 chemically equivalent carbon atoms

H CH3 H H HCCCCH H H H H There are four chemically different carbon atoms in the molecule so there are four peaks in the C-13 nmr spectrum. NO SPLITTING WITH C-13 ONLY ONE PEAK FOR

EACH CARBON Other isomers of C5H12 pentane CH3CH2CH2CH2CH3 3 peaks 2,3-dimethylpropane (CH3)4C 2 peaks CARBON-13 NMR SPECTRA - QUESTIONS How many peaks would you expect there to be in the carbon-13 spectrum of butane CH3CH2CH2CH3

2-methylpropane CH3CH(CH3)CH3 butanal CH3CH2CH2CHO butanone CH3COCH2CH3 pentan-2-one CH3COCH2CH2CH3 pentan-3-one CH3CH2COCH2CH3

cyclohexane C6H12 CARBON-13 NMR SPECTRA - QUESTIONS How many peaks would you expect there to be in the carbon-13 spectrum of butane CH3CH2CH2CH3 2 2-methylpropane CH3CH(CH3)CH3 2 butanal

CH3CH2CH2CHO 4 butanone CH3COCH2CH3 4 pentan-2-one CH3COCH2CH2CH3 5 pentan-3-one CH3CH2COCH2CH3

3 cyclohexane C6H12 1 19 CARBON-13 NMR SPECTRA - QUESTIONS Identify the isomers of C4H8O CARBON-13 NMR SPECTRA - QUESTIONS Identify the isomers of C4H8O A butanal B butanone C 2-methylpropanal

CARBON-13 NMR SPECTRA - QUESTIONS Identify the isomers of C6H12 CARBON-13 NMR SPECTRA - QUESTIONS Identify the isomers of C6H12 X hex-1-ene or hex-2-ene 2-methylpent-1-ene 3-methylpent-1-ene 2-methylpent-2-ene 3-methylpent-2-ene Y cyclohexane Z 2,3-dimethylbut-2-ene or or or or or

REVISION CHECK What should you be able to do? Recall the how an nmr spectrum is produced Explain and understand the origin of chemical shift Explain and understand the purpose of integration Explain and understand the purpose of shaking with D2O Recall the differences between high and low resolution spectra Explain and understand the origin of splitting patterns Interpret and explain a simple proton or carbon-13 nmr spectrum NUCLEAR MAGNETIC RESONANCE SPECTROSCPY THE END KNOCKHARDY PUBLISHING

Recently Viewed Presentations

  • Guideline Pearls - Thrombosis Canada

    Guideline Pearls - Thrombosis Canada

    Guideline PearlsDo's and Don'ts. Cerebrovascular. d. isease. Provide lifetime antiplatelet Rx to all patients post ischemic stroke or TIA. Consider DAPT with ASA + Clopidogrel in patients with high risk TIA or minor stroke for 30 days.
  • LITERARY TRANSLATION IN PRACTICE Lecce 10-12 May, 2012 ...

    LITERARY TRANSLATION IN PRACTICE Lecce 10-12 May, 2012 ...

    Gay "fourvery big BARMBRACKS...werereadytobehanded round at tea.". The term BARMBRACK . is. a modificationof BORREEN-BRACK whichderivesfrom the Irish BAIRGHIN (a cake/una torta) and BREAC (spotted/picchiettato) and refersto a cakewithcurrants.
  • 微少試験片を用いた 人工関節用uhmwpeの疲労特性評価

    微少試験片を用いた 人工関節用uhmwpeの疲労特性評価

    Delamination in virgin UHMWPE. Virgin UHMWPE. Virgin UHMWPE. Gamma air, AA. U-shaped motionat 100 cycles. Simple reciprocationat 1,000,000 cycles. U-shaped motionat 160,000 cycles. 10 mm. 1 mm. So, I'd like to introduce the U-shape motion. The U-shape motion was first...
  • Salsa and ChaCha: An Advanced Cryptanalysis

    Salsa and ChaCha: An Advanced Cryptanalysis

    Motivation. Standardization process for inclusion of cipher suite based on ChaCha20-Poly1305 AEAD in TLS1.3 is almost complete.. Existing cryptanalysis treats ciphers as . black-boxes. Brute force . search for multiple components in cryptanalysis. We need to know its security margins.
  • Microsoft Innovative Teachers Worldwide Forum

    Microsoft Innovative Teachers Worldwide Forum

    Siek aukštai, nes Tavo sieloje slypi žvaigždės. Svajok giliai, nes kiekviena svajonė ateina pirmiau už tikslą /Pamela Vaull Sarr/ TARPTAUTINĖ MOKYTOJŲ, TAIKANČIŲ IKT, PATIRTIS Redmondas, Vašingtono valstija, JAV, Liepos 18-19d., 2005 m.
  • Leaves: Structure and Function

    Leaves: Structure and Function

    Times New Roman Arial Wingdings Calibri Maple 1_Maple Leaves: Structure and Function Main Functions PowerPoint Presentation Structures Leaf Scars and Bundle Scars… PowerPoint Presentation PowerPoint Presentation PowerPoint Presentation Black Walnut Structure STRUCTURE 5.
  • 9A Inheritance and Selection - KirkmanEd - Home

    9A Inheritance and Selection - KirkmanEd - Home

    KS3 Biology 9A Inheritance and Selection Contents Contents Contents Contents Contents Glossary Anagrams KS3 Biology 9A Inheritance and Selection Contents Contents Contents Contents Contents Glossary Anagrams Note that this activity may raise some discussion, as some of the features are...
  • Memory-like NK Cells Exploit Innate Priming and Alternative

    Memory-like NK Cells Exploit Innate Priming and Alternative

    Memory-like NK Cells Exploit Innate Priming and Alternative Signaling Mechanisms to Enhance Function in HIV/SIV infection . R. Keith Reeves, Ph.D. Center for Virology and Vaccine Research . Harvard Medical School/BIDMC