structural elucidation fructose

1. STRUCTURAL ELUCIDATION OF FRUCTOSE
Presented by;
M Pharm (Pharmaceutical Chemistry) students
Gunturu .Aparna
Akshintala. Sree Gayatri
Thota. Madhu latha
Kamre. Sunil
Daram. Sekhar
University college of pharmaceutical sciences
Department of pharmaceutical chemistry
Acharya Nagarjuna University
Guntur
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2. STRUCTURAL ELUCIDATION
OF FRUCTOSE
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3.  Fructose also known as levulose or fruit sugar is found in many
fruits and in honey.
 It occur in combination with glucose in cane and beet sugars.
The most important source of fructose is the polysaccharide
inulin.
 Commercially, fructose is obtained by the hydrolysis of inulin.
 Crystalline D-fructose melts at 1040c, it is the sweetest of the
sugars, but is seldom used in pure form .it exibits mutarotation;
the specific rotation values of alfa- and beta –and equilibrium
mixture are -210, 133.50 and -92.30; respetively.
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4.  Fructose responds most of the usual properties of the ketonic
and hydroxyl groups.
 A very important property of the fructose is that although it
has no aldehydic group ,it reduces fehling solution and Tollen’s
reagent.
 This reducing property of fructose is said to be due to the
presence on an α-hydroxy ketonic group which is readily
oxidised by fehling and Tollen’s reagent.
Tartaric acid 4

5.  Fructose from an insoluble calicium fructosate with lime
water (difference from glucose) . This fact is utilised in the
separation of glucose and fructose by the hydrolysis of sucrose.
CONSTITUTION OF FRUCTOSE :
 From the qualitative and quantitative analysis ,fructose is
found to have its molecular formula as C6H12O6
 Fructose is found to have five hydroxyl groups on five
different carbon atoms .
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6.  Fructose forms a cyanohydrin and an oxime
indicating the presence of carbonyl group, since
fructose on oxidation with nitric acid gives a mixture
of tartaric acid and glycolic acid (each having lesser
number of carbon atoms), the carbonyl group is ketonic
in nature.
 The formation of glycolic and tartaric acids
indicates that the ketonic group is present at second
position.
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7.  On reducing with sodium amalgam and
water, fructose gives hexahydric acid and
sorbitol and mannitol.
 Which on further reduction with
hydriodic acid and red phosphorus gives
2-iodohexane and n-hexane which suggest
that in fructose molecule the six carbon
atoms are present in a straight chain.
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8.  Fructose on treatment with hydrogen cyanide gives
cyanohydrin which on hydrolysis followed by reduction
hydriodic acid and red phosphorus give n-butylmethylacetic
acid, CH3CH2CH2CH2CH(CH3).COOH
 The formation of this compound again indicates that the
ketonic group present at second position .
The straight chain structure of fructose may be written as
n-butylmethylacetic acid
Fructose
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9. Tartaric acidGlycolic acid
Fructose
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10.  CONFIGURATION OF FRUCTOSE:
 Since the above structure has three asymmetric carbon
atoms it may exist in eight (2
3 =8) optical isomers.
 The exact configuration of the fructose is established by that
it forms the same osazone as glucose indicating there by that
the configurations of C3to C6 atoms of fructose is same
as that of glucose.
 Hence the complete open-chain formula of fructose may be
written as below.
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11.  RING STRUCTURE OF FRUCTOSE:
 Fructose exhibits mutarotation and forms two methyl fructosides.
That is α and β forms.
 The commercial and natural free fructose is most probably β-isomer
with a pyranose ring. But the fructose found in sucrose (a
disaccharide) and inulin (a polysaccharide) is present inn furanose
ring which during hydrolysis is converted into more stable pyranose
form.
 Lastly , since the fructose is laevorotatory and has D-configuration
of glucose ,it is denoted by D(-)-fructose.
D-Fructose
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