29 Flashcards
What is in a TLC plate
How to locate
Stationary phase is the silica or alumina powder
Thid I’d an ADSROBENT SUBSTANCE, adsorbents are things that absorb, absorbent are things that get abdorbed
Based on relative interaction strength with the mobile phase or stationary phase, the different components will travel different distances
2) at the end use Uv light , or dry in fume cupboard and use iodine crystals thst shoe thr spots so yiu can cauktte raf
Gas chrmathrouph
Here the stationary phase is some liquid adsrobed onto a solid support
Mobile phade is inert carrier gas helium
The sample is injected in snd volatile it becomes gas
It then based on relative intervstikns with the inert gas csrrier or the liqhid adbsorbe staginsry ohase will spend different times in thr chamber, and so will have different retention time. Base Dom these you can seed
Gas Chor Tag roh used for
Volatile usbstanced idmfitnyijg substances and impurieted
Two things cna interpret from gas
So you will have retention time on x axis
And then y axis is peak area
Peak area is prottonsl to the concentration of substance in the sample
Thus you can make calibration curbed with peak area of known cknc to work out conc of an actual sample
And to idneifty it you use retention time data based on the things you used
For Halloween
Silver nitrate and aqueous ETHANOL in water bath heat and see milk cream butter
What is the idea behind NMR
Like electrons, nucleus with nucleons also have spin states , and this becomes significant only with an ODD number of nucleons, because it means the spin will not always align with the magnetic field, and so this can absorb radio frequency to change spin to be alligned and this is dtected
Infrared spec based on bonds abosvomb infrared , here itsodd nucleons absorbing radio waves
I’m this case when the nucleon rapidly changes spin state, this is called resonance
- we can checked what was absorbed by seeing what didn’t come out, and then co sore to database
How does a machine made
Will need a magnetic field , so typically asuperconducting electromagnet is used, which is a,de by using liquid helium to cool it down, so chlinderkwht electro agent and this is expensive
What kind stuff changed thr malunt of radio wave needed to aborb and cause resistance. What is this called
Based on the different ENVIRONMENT the carbon is in, and the atoms and proximity form it, will change the amount of frewuency needed. This is a CHEMICAL SHIFT , which is measured relative to TMS
Why is TMS THE STANDARD
Because it is a comoellety syu ethical susbtance, where all the carbons exist in the same environment snd all the Hydrogens too. As a result, it as a whole substance only absorbed ONE FREWUENCY
- on top of that it is an inert substance so won’t react
- also volatile so can be removed eaillh
Why is nmr so valuable to the organic chemist
We said can only be used for odd humber ncuekon thigns right
Well in ever hundred molecules there will be a carbon 13 isotope, so cna be used
And Hydrogens are odd anyways, so proton spec used
So very useful as can identify many substances
What is present in every sample thrn, but is filtere
Thr peak for thst is always ar 0 sometimes Fliegerei
And then to the left is chemical shift in PPM
Again why are like IR spec and N,R spec useful
Because no damage happens to the organic compund, and no change needs g9 happen using a trafionsl chemcils tedt which is long
How does Nkr work procedure prepared
1) dissolve din a solvent
2) tms is added
3) put in spectrometer which spins to even out magnetic imperfections
4). Eroded against tms and pulses of radio different sent through
Then a lauded after detected on co,liter.
Finally csn be recovered sgsin by evspfsting solvent, snd tms is voltisle do cuts anywahd
What is a deuterwted s9enf and why typically sued
Det rusted is like deutierukm, it got 2 1 hydrogen atoms, so isotope with more neutrons
As a result now is EVEN NUCELONS, so won’t produce a spec
Thus deuteltet compounds are typically Süd- as they will produce no spec and won’t interfere, they might produce a small one but computer will filter out
So it s because they habe eben amount of nucleons
How to identify chemical emebruoments
Base din the DIFFERENCE IN ATOMS THEY ARE BONDED TOO
- so like ch2 bs ch vs ch3 will all be differently
2) if SAME atoms bonded to, check if the PROXIMITY TO A SPECIAL ELECTONEGATIVE ATOM IS DIFFERENT
- closed atoms to it will be HIGHER CHEMICAL SHIFTZM WILL BE DIFFERENT ebbrjometn
If symmetrical. Then they exist in the SAMS CABRIN EMBRIOMENTZ, and remember to draw bith lines of symmetry
