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ULTRAVIOLET SPECTROCOPY (UV)ULTRAVIOLET SPECTROCOPY (UV)[[ : 100-190 (Vacuum UV), 190-400 (Near UV)]
ELECTRON TRANSITION BETWEEN ELETRONIC ENERGY LEVEL (n)
* (max 200 nm) * (max: 200-700
nm)n * (max: 150-250
nm)n * (max: 200-700
nm)
CHROMOPHORIC GROUP OF ORGANIC COMPOUND
CHROMOPHORIC GROUP
ABSORB ULTRAVIOLET ENERGY
CONJUGATED AND UNCONJUGATED DIENE CONJUGATED AND UNCONJUGATED TRIENE COMBINATION DIENE AND TRIENE KETONE CONJUGATED AND UNCONJUGATED OF UNSATURATED KETONE etc
THE MAIN TERMINOLOGIES OF THE UV SPECTROSCOPY
CHROMOPHORIC GROUPAUXOCHROME GROUP
RED SHIFT (BATOCHROMIC SHIFT)BLUE SHIFT (HYPSOCHROMIC SHIFT)
HYPERCHROMIC EFFECTHYPOCHROMIC EFFECT
maks = 256 nmmaks = 200 maks = 270 nm
maks = 1450
OHAuxochrome group
AUXOCHROME GROUP
BATOCHROMIC-HYPSOCHROMIC SHIFT AND HYPERCHROMIC-HYPOCHROMIC EFFECT
METHOD FOR PREDICTING THE MAXIMUM WAVELENGTH ( maks) OF UV ABSORBTION OF
ORGANIC COMPOUND
WOODWARD RULES
CONJUGATED DIENE ENONE
SUBTITUTED BENZENE
WOODWARD RULE FORCONJUGATED DIENE
BASE VALUE OF max : 1. ACYCLIC DIENE AND HETEROANNULAR ………………215 nm 2. HOMOANNULAR DIENE..……………………………………253 nm
INCREMENTS FOR: 1. – R (ALKYL) …………+ 5 nm 2. – OR (ALCOXY)……………+6 nm 3. – SR (TIOPHENE)……………………...+30 nm 4. – Cl, Br……………………………………...+5 nm 5. – OCOR ………………………………………....+0 nm 6. EXTENDING CONJUGATION –CH=CH-……………..+30 nm 7. EXOCYCLIC DOUBLE BOND…….………………………+5 nm
EXERCISES
CH2
CH2(a)
H3C CH3
(b) (c)
(d)(e)
AcO
(f)
AcO
(g)
HO
(h)
EXAMPLE OF UV SPECTRUM
WOODWARD RULE FOR ENONE
BASE VALUE OF max: AND 1. ACYCLIC ,-UNSATURATED KETONES AND SIX MEMBERED CYCLIC ,-UNSATURATED KETONES ….....................................215 nm 2. FIVE MEMBERED CYCLIC ,-UNSATURATED KETONES ……202 nm 3. ,-UNSATURATED ALDEHYDES………………… ……………..207 nm 4. ,-UNSATURATED CARBOXYLIC ACIDS AND ESTERS ……..195 nm
INCREMENTS FOR: 1. – R (ALKYL) ………………………+ 10 (), 12 (), 18 ( ), 18 () nm 2. – OR ……………………………….+ 35 ( ), 30 ( ), 17 ( ), 30 () nm 3. – SR…………………………………+ 85 () nm 4. – OH…………………………….....+35 ( ), 30 ( ), - (), 50 () nm 5. – Cl………………………….....…...+ 15 (), 12 () nm 6. – Br…………………………….…...+25 (), 30 () nm 7. – OCOR , -OCOAr…………..……+ 6 (, , , ) nm 8. – NR2…………………………...….+95 () nm 9. EXTENDING CONJUGATION –CH=CH-………………+30 nm 10. EXOCYCLIC DOUBLE BOND…….………………………+5 nm 11. HOMODIENE COMPONENT ………………………….+ 39 nm
EXERCISES
H3C
H3C
O
CH3
(a)
H3C
H3C
O
CH3OH
(b)
O
OCH3(c)
O
OH
OCH3
(d)
O
OH
(e)
H3CO
O
OC2H5
(f)
FIESER-KUHN RULE FOR POLIENE
max = 114 + 5 M + n (48 – 1,7 n) – 16,5 Rendo – 10 Rexo nm Max = (1,74 X 104) n
n = Sum of conjugated double bondM = Sum of alkyl group or like alkyl group on conjugated systemR endo = Sum of ring with endocyclic double bond on conjugated systemR exo = Sum of ring with exocyclic double bond on conjugated system
EXERCISES
O
HO
O
OH
(a)
O
CH3
HO
(b)
EXERCISES
EXERCISES
THE SUBTITUTED BENZENE
BASE VALUE maks OF PARENT CHROMOPHORES: 1. Z = R OR RING RESIDUE …………………….………………….....246 nm 2. Z = H ……………………………………………………………………..250 nm 3. Z = OH OR OR …………………………….………………………..230 nm INCREMENTS FOR: ortho meta para 1. – ALKYL /RING RESIDUE………… 3 3 10 2. – OH,OR ………………………………. 7 7 25 3. – O………………………………………11 20 78 4. – Cl………………………….....……….. - - 10 5. – Br…………………………….……….. 2 2 15 6. – NH2………………………...……..…..13 13 58 8. – NHAc….…………………………...…20 20 45 9. –NHMe…………………………….…….- - 73 10. –NMe2…………….……………………20 20 85
EXERCISES
(a)
O
OC2H5
H2N
OCH3(b)
O
OH
H3CO
O(c)
O
(d)
Cl CH3 O
OC2H5
(e)O
H3CO
OCH3