[pinke]

Hi

I just have synthesized a chemical compound, now i want to go for characterization part. please tell me the important steps.

1.Melting point
2.Mass spec
3.Nmr
4.IR

Is there anything else to be done ? among 1H nmr, 13C nmr, which one is costlier ?


PS: Iam a biologist , iam not so good at chemistry. so please suggest me

Thank you

[Dan]

1.Melting point
2.Mass spec
3.Nmr
4.IR

That is enough for most chemistry journals (assuming you do high resolution mass spec [HRMS]). Other techniques that spring to mind are elemental analysis and X-ray analysis.

Another property that is usually given is the retention factor (R_f) on a silica TLC plate.

among 1H nmr, 13C nmr, which one is costlier ?

¹³C NMR is more expensive than ¹H because it takes longer (due to the low natural abundance of ¹³C), but you need both ¹H and ¹³C. Depending on the complexity of the structure, you may require additional experiments such as DEPT, COSY, HSQC, HMBC, NOESY etc. for a convincing structural assignment. If your molecule contains F or P, you should get ¹⁹F and ³¹P spectra as well.

[pinke]

Thanks for the clarification Dan 

please tell me Why do we need both Nmr's ? iam planning to get only 1H nmr ? isn't it alone sufficient ?

[Dan]

please tell me Why do we need both Nmr's ? iam planning to get only 1H nmr ? isn't it alone sufficient ?

While a ¹H NMR is often sufficient for a quick identification of simple molecules with good confidence, it doesn't provide information about the C atoms, so it is not enough for a completely convincing structural assignment - ¹³C NMR is more evidence for the assigned structure, the more evidence you have, the more confidence in your assignment. In some cases, even more NMR experiments would be required for convincing assignment.

A simple case illustrating the need for ¹³C is:

and

They would have very similar ¹H NMR spectra.

Many journals insist on ¹³C spectra for novel compounds. Whether ¹H is enough for publication depends on the molecule, the method of preparation and the journal in which it is published. My personal opinion is that you should report a ¹³C spectrum for any novel compound regardless of whether the journal requires it.

If the compound is not novel - i.e. it has already been characterized in the literature - then ¹H NMR is "enough" provided your data matches the literature, and the literature interpretation of the data is sound.

[pinke]

Okay...Thanks for explaining dan, stay blessed

[pinke]

I have been given four spectra, how to identify /  differentiate   UV, IR Spectra, 1H Nmr, 13C Nmr ? initially just by looking at them ? please help me   

Thank you


PS: Iam from pure biology stream, not so good at chemistry

[kriggy]

Yeah you can identify them just by looks..
UV is absorbance vs vawelenght.. like this http://chemwiki.ucdavis.edu/@api/deki/files/5066/image037.png?revision=1
IR is transmitance vs vawenumber like this https://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/Spectrpy/Images/vanillin.gif
NMR looks like this one http://cnx.org/resources/28eae6eb8c507d72a5fbf0595969085dbaa43442/Fig21.jpg
the difference between 1H and 13C is that is different range of chemical shift (x axis) in hydrogen spectra its 0-13 usualy and in carbon its 0-250 and that the peaks in 13C doesnt show the splitting patterns like hydrogen spectrum usualy.

Also, usualy in the spectra its written somewhere on the side - if you print them - that its IR/UV/NMR etc..

[pav]

Thank you soo much..now its clear for me..

 Can you please help me in this issue too..

we have sent few samples to a lab and got Hplc data , they sent us hplc chromatogram in
*.fid format, its a raw data format, we are unable to open that file to get the data from it. could you please kindly tell me what kind of tool is required to access that chromatogram file ? i need to submit the data immidiatley. i tried with all these softwares LC Solutions, mestrenova, .openchrom, and other chromatogram visualizing tools. it was saying as incorrect /unknown file format, when i contacted that lab, they said there is nothing wrong with that .fid file,It was opening in their system and stopped responding further, so please kindly help me.. i want it in a pdf or image format.

pleaseeee help me. Thank you

[Arkcon]

they sent us hplc chromatogram in
*.fid format, its a raw data format, we are unable to open that file to get the data from it.

It appears that you can use this software to access this particular file extension:  https://en.wikipedia.org/wiki/OpenChrom

Failing that, you can ask whoever ran it for you to help.

could you please kindly tell me what kind of tool is required to access that chromatogram file ? i need to submit the data immidiatley. i tried with all these softwares LC Solutions, mestrenova, .openchrom, and other chromatogram visualizing tools. it was saying as incorrect /unknown file format, when i contacted that lab, they said there is nothing wrong with that .fid file,It was opening in their system and stopped responding further, so please kindly help me.. i want it in a pdf or image format.

Can you read that out loud, to yourself or anyone else, and possibly see if there's anything wrong with your request?

pleaseeee help me. Thank you