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