SPECTROSCOPY DATA of ASPIRIN

 Dear blog reader , this post is for brushing up our fundamentals of spectroscopy using simple molecules like aspirin
text may be less but graphs are educative. one can browse through this to brush up




Product Name: Acetylsalicylic acid CAS:50-78-2










1H NMR



 

    Assign.     Shift(ppm)

      A            11.
      B             8.125
      C             7.624
      D             7.356
      E             7.142
      F             2.352
  ABOVE IS PROTON NMR OF ASPIRIN AND ITS INTERPRETATION

abelled.



The peaks I have are:

2.30ppm (I this is a singlet and would be F)
7.07ppm (I think this is E)
7.29ppm (I think this is D)
7.53ppm (I think this is C)
8.05ppm (I think this is B)
11.44ppm (this is a singlet and would be A)


For B,C,D,E I need to say what kind of splitting pattern there would be and how many coupling constants are present and there approximate value. I think I know the assignments of them but I don't know the splitting pattern or coupling constants.

Would E and B be doublet of doublets because they couple with D and C so they would have ortho and meta coupling?

Would D and C be coupling with each other and B and E so would they be doublet of doublets of doublets, with two ortho and one meta coupling?

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 BELOW IS IR OF ASPIRIN KBR DISC









IR in nujol mull

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MASS SPECTRUM







above is mass spectrum of aspirin

o-acetoxybenzoic acid
C9H8O4              (Mass of molecular ion:    180)

 Source Temperature: 170 °C
   Sample Temperature: 100 °C
   DIRECT, 75 eV

13 C NMR

 


above is 13 C NMR OF ASPIRIN

50.18 MHz
C9 H8 O4	0.039 g : 0.5 ml CDCl3

 ppm   Int.  Assign.

      170.20   450      1
      169.76   510      2
      151.28   560      3
      134.90   924      4
      132.51  1000      5
      126.17   986      6
      124.01   974      7
      122.26   397      8
       20.99   674      9

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below is Raman spectra of aspirin





NMR INTERPRETATIONS

H-NMR spectral analysis

CAS NO. 50-78-2, Acetylsalicylic acid H-NMR spectral analysis

C-NMR spectral analysis

CAS NO. 50-78-2, Acetylsalicylic acid C-NMR spectral analysis H, H-COSY spectrum In H, H-COSY spectrum are on both axes, the 1 H chemical shifts plotted; In principle, both the axes 1 to see H-NMR spectra. Thus, there is a symmetric to the diagonal diagram. 1 H-NMR spectrum of acetylsalicylic acid Fig.2 H, H-COSY spectrum of acetylsalicylic acid In the spectrum, only the range from 7.0 to 8.2 ppm is applied, because only here HH scalar couplings can be expected. Fig.3 There are two types of signals: Diagonal signals: join the coordinates δ a δ a (in core A), δ b δ b (in core B) ... on, but play no role in the evaluation of the couplings between different cores, since it is only the signal of a nucleus is. The diagonal with all its signals corresponding to the 1D H-NMR spectrum. EXAMPLE Acetylsalicylic acid 7.13 ppm / 7.13 ppm = δ 2 δ 2 (H atom 2) 7.34 ppm / 7.34 ppm = δ 4 δ 4 (H atom 4) 7.61 ppm / 7.61 ppm = δ 3 δ 3 (H atom 3) 8.11 ppm / 8.11 ppm = δ 5 δ 5 (H atom 5) Cross signals: These signals are based on the scalar spin-spin coupling and are suitable for the evaluation of spectra of enormous importance. EXAMPLE Acetylsalicylic acid 7.13 ppm / 7.61 ppm (δ 2 δ 3 ), and 7.61 ppm / 7.13 ppm (δ 3 δ 2 ) - vicinal coupling between the H-atoms 2 and 3 7.34 ppm / 7.61 ppm (δ 4 δ 3 ) and 7.61 ppm / 7.34 ppm (δ 3 δ 4 ) - vicinal coupling between the H-atoms 4 and 3 7.34 ppm / 8.11 ppm (δ 4 δ 5 ) and 8.11 ppm / 7.34 ppm (δ 5 δ 4 ) - vicinal coupling between the H-atoms 4 and 5 In general it can be seen in the COSY spectrum each scalar coupling between two nuclei at four signals (two cross and two diagonal peaks) resulting connected a square; in the following example, the vicinal coupling between the H atoms is highlighted 3 and 4. Fig.4 With good resolution of the COSY spectrum, the coupling constants can be determined from the fine structure of the cross and diagonal signals, but this is rarely done because of the 1-D H-NMR spectra is easily possible. DRUG APPROVALS BY DR ANTHONY MELVIN CRASTO .....FOR BLOG HOME CLICK HERE Join me on Linkedin Join me on Facebook FACEBOOK Join me on twitter      Join me on google plus Googleplus  amcrasto@gmail.com KHAJURAHO INDIA Location of Khajuraho Group of Monuments in India. Location in Madhya Pradesh Khajuraho Group of Monuments - Wikipedia, the free ... en.wikipedia.org/wiki/Khajuraho_Group_of_Monuments The Khajuraho Group of Monuments are a group of Hindu and Jain temples in Madhya Pradesh, India. About 620 kilometres (385 mi) southeast of New Delhi, ... Hotel Chandela - A Taj Leisure Hotel