DR ANTHONY MELVIN CRASTO,WorldDrugTracker, helping millions, A 90 % paralysed man in action for you, I am suffering from transverse mylitis and bound to a wheel chair, With death on the horizon, nothing will not stop me except God................DR ANTHONY MELVIN CRASTO Ph.D ( ICT, Mumbai) , INDIA 25Yrs Exp. in the feld of Organic Chemistry,Working for GLENMARK GENERICS at Navi Mumbai, INDIA. Serving chemists around the world. Helping them with websites on Chemistry.Million hits on google, world acclamation from industry, academia, drug authorities for websites, blogs and educational contribution
Showing posts with label Mass of 2-heptanone. Show all posts
Showing posts with label Mass of 2-heptanone. Show all posts

Friday 18 September 2015

Mass of 2-heptanone

.

Steps to interpret a mass spectrum:
1.  Look for the molecular ion peak.
  • This peak (if it appears) will be the highest mass peak in the spectrum, except for isotope peaks.
  • Nominal MW (meaning=rounded off) will be an even number for compounds containing only C, H, O, S, Si.
  • Nominal MW will be an odd number if the compound also contains an odd number of N (1,3,...).
2.  Try to calculate the molecular formula:
  • The isotope peaks can be very useful, and are best explained with an example.
    • Carbon 12 has an isotope, carbon 13.  Their abundances are 12C=100%, 13C=1.1%.  This means that for every 100 (12)C atoms there are 1.1 (13)C atoms.
    • If a compound contains 6 carbons, then each atom has a 1.1% abundance of (13)C.
    • Therefore, if the molecular ion peak is 100%, then the isotope peak (1 mass unit higher) would be 6x1.1%=6.6%.
    • If the molecular ion peak is not 100% then you can calculate the relative abundance of the isotope peak to the ion peak.  For example, if the molecular ion peak were 34% and the isotope peak 2.3%:  (2.3/34)x100 = 6.8%.  6.8% is the relative abundance of the isotope peak to the ion peak.  Next, divide the relative abundance by the isotope abundance:  6.8/1.1=6 carbons.
  • Follow this order when looking for information provided by isotopes:  (A simplified table of isotopes is provided in the introduction, more detailed tables can be found in chemistry texts.)
    • Look for A+2 elements:  O, Si, S, Cl, Br
    • Look for A+1 elements:  C, N
    • "A" elements:  H, F, P, I
3.  Calculate the total number of rings plus double bonds:
  • For the molecular formula:  CxHyNzOn
    • rings + double bonds = x - (1/2)y + (1/2)z + 1
4.  Postulate the molecular structure consistent with abundance and m/z of fragments.
  • More information on specific fragmentation can be found in the quiz for each functional group.


 electron impact mass spectrum of 2-heptanone. The whole molecule is 114, the acylium ion is 43: