elusidasi struktur isolat

1. ELUSIDASI
STRUKTUR

3. BANYAK SAMPEL
Selective methods Number of sample
Chemical characterization 10 mg
Physical identification 1 mg
Infra red spectrophotometer 1 mg
Ultraviolet/visible spectro. 1 µg
Mass spectrometer 1 µg
GCMS 1 mg
NMR (H) 60 – 600 MHz 5 – 50 mg
NMR (C) 15 – 150 MHz 5 – 50 mg

4. LANGKAH-LANGKAH
ELUSIDASI STRUKTUR
1. Penentuan DBE/UN
n UN jumlah dari ikatan rangkap yang
mungkin dimiliki oleh suatu senyawa
n Misal senyawa : CaHbOcNdXe
n UN = (2a+2)-(b-d+e)
2

5. U = UN = the unsaturation number
U or UN can be interpreted as follows ;
U = 0 ; no doble bonds, no triple bonds, no rings
U = 1 ; one doble bond, or one ring
U = 2 ; two doble bonds, or two rings, or one doble bond and
one ring or one triple bond
U = 3 ; three doble bonds, or three rings, or two
doble bonds and one ring, or one doble bond and two rings,
or one triple bond and one ring, or one triple bond and one doble
bond.
U = 4 ; usually benzene ring or
U = 5 ; benzene plus one doble bond or one ring

6. LANGKAH-LANGKAH
ELUSIDASI STRUKTUR
2. Spektrofotometri Ultraviolet
- Panjang gelombang maksimum
3. Spektrofotometri Inframerah
- Bilangan gelombang pada daerah gugus fungsi
4. Spektrometri Massa
- Massa molekul
- Rumus molekul dan formula
- Pola fragmentasi

7. 5. H-NMR
Empat informasi yang dibutuhkan dalam
interpretasi spektra H-NMR :
1. Banyaknya sinyal yang berbeda, menunjukkan
tipe proton yang terkandung dalam senyawa
tersebut.
2. Geseran Kimia, menunjukkan lingkungan
elektron.
3. Intensitas atau Integrasi, menunjukkan jumlah
proton dirinya sendiri
4. Splitting, menunjukkan jumlah proton dari atom
H tetangga

8. Proton dalam satu molekul
Depending on their chemical
environment, protons in a molecule are
shielded by different amounts.
=>

9. Jumlah Sinyal
Hidrogen yang ekivalen memiliki geseran
kimia yang sama
=>

14. Pelarut 1H NMR 13C NMR
Acetic Acid 11.65 (1) , 2.04 (5) 179.0 (1) , 20.0 (7)
Acetone 2.05 (5) 206.7 (13) , 29.9 (7)
Acetonitrile 1.94 (5) 118.7 (1) , 1.39 (7)
Benzene 7.16 (1) 128.4 (3)
Chloroform 7.26 (1) 77.2 (3)
Dimethyl Sulfoxide 2.50 (5) 39.5 (7)
Methanol 4.87 (1) , 3.31 (5) 49.1 (7)
Methylene Chloride 5.32 (3) 54.00 (5)
Pyridine 8.74 (1) , 7.58 (1) , 7.22 (1) 150.3 (1) , 135.9 (3) , 123.9 (5)
Water (D2O) 4.8

15. Integration
Integration is defined as the area underneath each
signal.
This area is proportional to the number of
hydrogens contributing to that signal.
In most instances, the student will not have
available the chemical formula of the unknown
compound.

16. To calculate the number of hydrogens per signal,
first add up all of the integration values.
Divide each area by the total area.
Divide by the lowest number and multiply by the
same factor to get all of the numbers to whole
values.
If there are three signals, the following equations
are used.

20. Intensity of Signals
n The area under each peak is
proportional to the number of protons.
n Shown by integral trace.
=>

21. How Many Hydrogens?
When the molecular formula is known,
each integral rise can be assigned to a
particular number of hydrogens.
=>

22. Multiplisitas
The theoretical measure of the line composition in
multiplets arises from the coefficients of the
expanded polynomial, as seen in Pascal's triangle
In simple terms, the number of peaks, within a signal,
is equal to the number of hydrogens on the adjacent
carbons plus one.
On a spectrum, the number of peaks, within a signal,
minus one is equal to the number of hydrogens on
adjacent carbons.

25. SPEKTRA KARBON C-13
Tiga tipe informasi yang dapat digunakan dalam
interpretasi spektra :
1. Jumlah sinyal yang berbeda, mengindikasikan
jumlah tipe karbon yang ada
2. Geseran kimia, mengindikasikan lingkungan
elektronik
3. Metode DEPT, Sinyal diinterpretasi sebagai CH3,
CH2, CH, or C.

28. GESERAN KIMIA

32. Splitting
Nowadays, all carbon-13 NMR spectra are run
decoupled.
Decoupling removes all of the splitting between
carbon and hydrogen.
If the spectra were run coupled, then a CH3 would
show up as a quartet, a CH2 would show up as a
triplet, a CH would show up as a doublet, and a C
would show up as a singlet.
This type of information is obtained from DEPT
spectra

33. DEPT
Metode ini (Distortionless Enhancement by
Polarization Transfer (DEPT)) spektrum, CH3, CH2,
CH, dan C dapat dibedakan .
A proton pulse is set at 45°, 90°, and 135° in three
separate experiments.

34. DEPT spectra are presented in two basic ways.
In one type of DEPT spectra,
the methyls are positive at 135°, zero at 90°, and
positive at 45°;
methylenes are negative at 135°, zero at 90°, and
positive at 45°;
and the methines are positive at 135°, positive at
90°, and positive at 45°.
In a second type of DEPT spectra, separate
spectra are obtained for the methyls, methylenes,
and methines.