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Butane

In the molecule CH 3 CH 2 CH 2 CH 3 size 12{ ital "CH" rSub { size 8{3} } ital "CH" rSub { size 8{2} } ital "CH" rSub { size 8{2} } ital "CH" rSub { size 8{3} } } {} , the methyl groups are equivalent and the methylene groups are equivalent. As described earlier, we would expect to see two signals in a 3:2 ratio. If we now consider coupling, we see that the methyl groups are attached to methylene groups. The CH 3 size 12{ ital "CH" rSub { size 8{3} } } {} protons will thus be split into triplets by the methylene protons. Likewise, the methylene protons will be split into quartets by the protons on the methyl groups. However, notice that because the methylene groups are equivalent, they do not couple to each other. Therefore, we expect to see the same pattern as that predicted for the ethyl group shown above.

More Complex Coupling Patterns

If a hydrogen atom is attached to a carbon atom to which nonequivalent carbon atoms with different numbers of protons are attached, then a more complex pattern is observed. One arrives at the total number of signals expected by multiplying the individual couplings. For example, consider 1,2-dichloropropane with three carbon atoms having different protons attached:

The CH 3 size 12{ ital "CH" rSub { size 8{3} } } {} protons will see one adjacent proton and the signal will be split into a doublet. The CH 2 size 12{ ital "CH" rSub { size 8{2} } } {} group will likewise be split into a doublet by the CH proton. Coupling between the CH 3 size 12{ ital "CH" rSub { size 8{3} } } {} group and the CH 2 size 12{ ital "CH" rSub { size 8{2} } } {} group will generally not be observed. However, the CH group in the middle is adjacent to two different types of carbon atoms with different numbers of protons attached. This CH group will be split into a quartet by the CH 3 size 12{ ital "CH" rSub { size 8{3} } } {} group and into a triplet by the CH 2 size 12{ ital "CH" rSub { size 8{2} } } {} group. The overall pattern will have 4 x 3 lines, or a total of 12, if our instrument is able to resolve all the lines. This pattern would be described as either a triplet of quartets or a quartet of a triplet, depending upon which coupling constant is larger. Often, these complex patterns are not cleanly resolved and a very complex spectrum results. The two limiting possibilities for the CH group would look something like the following. Notice that there are two different coupling constants in each case.

Quartet of triplets

Triplet of quartets

Experimental

You will be given a packet of several spectra. Using the chart and the information on chemical shifts, coupling patterns, and integrated intensities given above as a guide, identify the unknown organic compounds. Answer some review questions to refresh your mind. We will work on number 2 and 5 with you.

Lab Revision Questions: NM

(Total 20 Points)

On my honor, in preparing this report, I know that I am free to use references and consult with others. However, I cannot copy from other students’ work or misrepresent my own data.

…………………………………………………………….. (signature)

Print Name: _________________________________________

1. The atomic weight of Br is listed as 79.909 on the periodic table, but we use 79, not 80, when calculating the molecular weights of Br-containing compounds for mass spectrometry – why? (2 points)

2.

(a) Draw trans-3-bromo-1-butylcyclohexane in planar form (no chair). Be sure to indicate the stereochemistry in your drawing. (2 points)

(b) Now draw both chair conformations of trans-3-bromo-1-butylcyclohexane. (2 points)

(c) Circle the conformer above that is lower in energy. (1 point)

3.

(a) How many degrees of unsaturation does C 5 H 7 ClO size 12{C rSub { size 8{5} } H rSub { size 8{7} } ital "ClO"} {} have? (2 points)

(b) Draw an isomer of C 5 H 7 ClO size 12{C rSub { size 8{5} } H rSub { size 8{7} } ital "ClO"} {} that contains a ketone (There are many correct answers.). (2 points)

(c) Draw an isomer of C 5 H 7 ClO size 12{C rSub { size 8{5} } H rSub { size 8{7} } ital "ClO"} {} that does not contain a ketone. (Again, there are many correct answers.). (2 points)

4. Explain why 3-Chloropentane shows four different absorbencies in the 1 H size 12{ {} rSup { size 8{1} } H} {} NMR spectrum. (3 points)

5. Write the structure from the data given. (4 points)

Molecular formula C x H y NBr size 12{C rSub { size 8{x} } H rSub { size 8{y} } ital "NBr"} {}

IR:

1 H size 12{ {} rSup { size 8{1} } H} {} NMR:

13 C size 12{ {} rSup { size 8{"13"} } C} {} NMR:

Report QuestionsNMR Laboratory

(Total 70 Points)

On my honor, in preparing this report, I know that I am free to use references and consult with others. However, I cannot copy from other students’ work or misrepresent my own data.

…………………………………………………………….. (signature)

Print Name: _________________________________________

1. Explain each of the following observations. (3 X 2= 6 points)

(a) The compound CH 3 CH 2 CH = CH 2 size 12{ ital "CH" rSub { size 8{3} } ital "CH" rSub { size 8{2} } ital "CH"= ital "CH" rSub { size 8{2} } } {} shows an IR absorbance around 1550 cm–1, but its structural isomer CH 3 CH = CHCH 3 size 12{ ital "CH" rSub { size 8{3} } ital "CH"= ital "CHCH" rSub { size 8{3} } } {} does not-why?

(b) The 1 H size 12{ {} rSup { size 8{1} } H} {} -decoupled 13 C size 12{ {} rSup { size 8{"13"} } C} {} NMR spectrum of CHF 3 size 12{ ital "CHF" rSub { size 8{3} } } {} shows a single peak that is split into a quartet.

2.

(a) Draw trans-4-(1-ethylpropyl)cyclohexanol in planar form (no chair). Be sure to indicate the stereochemistry. (2 points)

(b) Now draw trans-4-(1-ethylpropyl)cyclohexanol in its lowest energy conformation. (2 points)

(c) Now draw cis-4-(1-ethylpropyl)cyclohexanol in its lowest energy conformation. (2 points)

(d) Considering your answers to (b) and (c), which is lower in energy, cis or trans-4-(1-ethylpropyl)cyclohexanol? Explain your answer briefly (one sentence). (2 points)

3. In the following compound, label symmetry-equivalent H atoms with the same letter and nonequivalent H atoms with different letters, as we did in class. Then predict the 1 H size 12{ {} rSup { size 8{1} } H} {} NMR spectrum of the compound, indicating the approximate chemical shift, integration, and multiplicity for each resonance that you expect to see. (20 points)

4. Below are the IR spectra of two isomers having the formula C 7 H 7 Cl size 12{C rSub { size 8{7} } H rSub { size 8{7} } ital "Cl"} {} . (Total 8 points)

1) What is the unsaturation number of these isomers? _____ (2 points)

2) Why is there such a difference in the intensity of the C-H stretching and C-H bending region between these two isomeric compounds? (2 points)

3) What structure would you assign to Compound A? Indicate on the spectrum which IR bands support your structure assignment. (4 points)

4. What structure would you assign to Compound B? Indicate which IR bands support your structure assignment. Note: NUJOL is a paraffin oil used to prepared the IR sample. (8 points)

5. Find the structure of the compound and explain each spectrum to support your answer.

(a) Compound contains C, H, and O. (10 points)

MS:

IR:

1 H size 12{ {} rSup { size 8{1} } H} {} NMR:

13 C size 12{ {} rSup { size 8{"13"} } C} {} NMR:

(b) Compound contains C, H, and O. (10 points)

MS:

IR:

1 H size 12{ {} rSup { size 8{1} } H} {} NMR:

13 C size 12{ {} rSup { size 8{"13"} } C} {} NMR:

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Chem 215 spring08. OpenStax CNX. Mar 21, 2008 Download for free at http://cnx.org/content/col10496/1.8
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