Selective Biocatalytic Oxidation of Alcohols:

Developing a ‘Green’ Oxidizing Agent

NITU SINHASTELLA MARIS COLLEGE

@ Indian institute of Madras

INTRODUCTION WHY BIO OXIDATION OBJECTIVE METHODLOGY RESULT

CONTENTS:-

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An enantiopure drug is a pharmaceutical that is

available in one specific enantiomeric form.

Most biological molecules (proteins, sugars, etc.) are

present in only one of many chiral forms, so different

enantiomers of a chiral drug molecule bind

differently (or not at all) to target receptors.

INTRODUCTION:-

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One enantiomer of a drug may have a desired

beneficial effect while the other may cause serious

and undesired side effects.

Ethambutol: One enantiomer is used to

treat tuberculosis, the other causes blindness.

Naproxen: One enantiomer is used to treat arthritis

pain, but the other causes liver poisoning with no

analgesic effect

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Biocatalysts for oxidation ….Why?

1.Mild Reaction Conditions 25-35º C, near neutral pH and std. pressure.

2.High Specificity

Chemo specificity

Selectivity for a compound or group of compounds (eg: Chemo selective bio-oxidation of primary alcohol by Janibacter terrae DSM 13953)

Regio specificity:-

Selectivity among similar groups on the same molecule

(eg: Selectivity among hydroxyl groups at different positions in the same molecule of polyol)

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O OH

OH

HO

OHHO

O

OH

HO

OHHO

OADH/AlcOx

Stereo specificity :-

Selective for one stereoisomerStereo-selectivity between a (S)- and (R) configured sec-alcohol centers in a meso-diol

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3. Controllability (eg: bio-oxidation of benzyl alcohol to the corresponding aldehyde avoiding over oxidation to benzoic acid using oxidases, isolated alcohol dehydrogenases (ADHs).

Janibacter terrae DSM 13953 )

4. Biodegradable waste management problems reduced.

5. Primary and secondary alcohols are important in the pharmaceutical, agricultural and food

Industries.

Orbegozoa. T, I. Lavanderab, W. M.F. Fabiana, B. Mautnerb, J. G. de Vriesc and W. Kroutil. Tetrahedron 2009: 65, 346805-6809

- : Potentially– biological oxidation reactions can provide feasible alternative to chemical synthesis.

Fast gaining importance as eco friendly “GREEN TECHNOLOGY”

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1. Traditional alcohol oxidation has been performed with heavy metals (eg. Cr,Mn)2. Metal-free alcohol oxidation usually depends on moisture – sensitive oxidants and environmentally undesirable reaction media such as chlorinated solvent. (eg: Dimethyl sulfoxide as oxidant in the presence of an ‘activating’ reagent such as N,N’-dicyclohexylcarbodimide) 3. Aldehydes are in general not stable in the conventional chemical oxidation conditions of

primary alcohols

Why not CHEMICAL????????

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Biocatalytic oxidation:- 1. Whole-Cell oxidation

Whole-cell oxidations are used when - enzyme is intracellular.

- enzyme needs a cofactor to carry out the catalysis. - for multienzymatic process.

Enzymes as catalyst-For the oxidation of alcohols two types of

oxidoreductase have been employed most frequently Dehydrogenases and Oxidases. (Peroxidase and mono oxygenases were employed to lesser extent).

Chemo-enzymatic methods - Example: TEMPO (2,2,6,6-tetramethylpiperidin-1-

yloxy) and enzymes (Laccase) for the oxidation of primary alcohols.

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This is a chemical reduction of alpha tetralone with ethanol.In order of preparation of substrate.It’s a overnight reduction over a magnetic stirrer in round bottom flask.Then work up process for reduction was done with DCM in separating flask.

SODIUM BOROHYDRIDE REDUCTION

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1. Silica gel with 100% hexane in column. 2. solvent :- 1% ,2%,3% ,4%,5%,6%,7% and 8% of ethyl acetate and hexane. 3. with condition column was eluted and tlc was check with every alternative tubes of column fraction. 4. Then fraction having the desired compound is concentrated by vacuum Rota vapor.

-By this compound is collected.

COLUMN CHROMATROGRAPHY

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1.Biocatalytic oxidation of selected secondary alcohol using candida parapsilosis ATCC 7330.2.Optimization for Biocatalytic oxidation condition such as:-Biomass:-pH:-Substrate concentration:-solvent concentration for dissolving substrate. :-Reaction volume:-Reaction time.

OBJECTIVE:-

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BIOTRASFORMATION PROCEDURES Candida parapsilosis ATCC 7330 is grown in YMB medium.(40hr)Cells were harvested by centrifuge.(4.c, 6000 rpm, 15mins)Wasted twice and suspended with distilled water (7.6pH)Reaction was done in orbital shaker at 150 rpm, 25.c.The product was isolated wit ethyl acetate by vacuum rotator vapor.

METHDOLOGY:-

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Conversion of substrate can determine by reverse phase HPLC using C-18.

FTIR is done for, functional groups detection.

NMR is done for determination compound purity.

METHOD OF ANALYSIS:-

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Oxidation by candida parapsilosis was successfully performed and the conversion was 30% in chrial column.

RESULTS:-

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