HPOPS

The reaction can be followed by measurement of dye formation. The rate of oxygen depletion can be measured using an oxygen electrode. Additional reagents can be added to prevent the formation of oxygen from the generated HpOp. The reactions ate as follows ... 

HPOPS=(i )-2-(4-hydroxyphenoxy)propionic acid POPS=(R)-2-phenoxypropionic acid (Dingier et al, 1996)... 

In crop protection, the processes to herbicide intermediates (I )-HPOPS and (S)-MOIPA are described. A process catalyzed by an organometallic compound (Ir— ferrocene derivative) has turned out to be superior to the transaminase-catalyzed biocatalytic route to (S)-MOIPA whereas enzymatically-catalyzed aromatic hydroxy-lations with HPOPS as an example are the method of choice. 

BASF (Ludwigshafen, Germany) produces isomerically pure (i )-2-(4-hydroxy-phenoxy)-propionic acid (HPOPS) from (P)-2-phenoxypropionic add (POPS) on a 100 m3 fermenter scale for use as a herbicide intermediate (Figure 7.30) (Cooper, 1990). 

For the illustration of a typical timescale of the development of a biotransformation at BASF, the hydroxylation of aromatics serves as an example BASF took three years to increase the product titer from 1-5 g I. 1 to 40 g I.1, another four years after mutation of the parent strain to jump from 40 to 120 g I.1. The hydroxylation of aromatics (POPS to HPOPS) today runs on a scale of > 100 tpy. 

Figure 16.3-14. Regioselective para-hydroxylation of (R)-2-phenoxypropionic acid catalyzed by Beauveria bassiana (HPOPS process).

The hydroxylation of aromatics serves as an example for a sussessfiiU industrial production of intermediates in a technical scale. BASF Ludwigshafen produces iso-merically pure (iJ)-2-(4-hydroxyphenoxy)-propionic acid (HPOPS) from (iJ)-2-phe-noxypropionic acid (POPS) in a 100 m fermenter for use as a herbicide intermediate (Eq. 4-19). 

The acid phosphates of tetravalent metals are well known as ion-exchangers. They can be prepared as layered crystalline materials in two different structural modifications labeled a- and y-forms respectively. The alpha products have the general formula M(rV)(HPOp H O (with M(TV) = Zr, Ti,... 

Methyl 6-deoxy-6-hydroxyamino-a-D-glucopyranoside has been synthesized by oxidation of the 6-amino-glycoslde to a 6-oxlme (HpOp-Na tungstate), and reduction (NaBH CN) 6 -N-hydroxy-... 

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