Synthesis Of Catechols

Figure 15.9 Synthesis and in situ recovery of 3-phenylcatechol.

of 80 to 90%, and after desorption and isolation of product, overall yields of 60 to 80% were estimated.41 The entire process was scaled up to the 300 L scale, resulting in the formation of a total of 1.1 kg 3-phenylcatechol, at a purity of 77%. One crystallization was sufficient to bring 25 g of the material to a purity of >98%; this compound is now for sale by Fluka, in Switzerland.

Though a detailed life-cycle analysis has not yet been made, the reagents that go into these biocatalytic reactions already indicate a certain trend. Besides starting materials the route requires only salts, glucose, glycerol and air, XAD-4 for product extraction, acidified methanol for product elution, and a solvent for product polishing (hexane or methanol/acid mixtures). With the exception of the XAD-4 resin, all reagents are from renewable or almost inexhaustible stocks. With sufficient XAD-4 reuse—exceeding a hundred or so cycles—waste streams are minor and comparatively green since they consist mainly of biomass and water.

This bioconversion illustrates several points. First, E. coli is a highly adequate host for the bioconversion of toxic compounds. Second, it is possible to attain adequate fluxes at low concentrations of substrate. Third, it was relatively easy to scale up the system from laboratory (several liters) to pilot scale (several hundred liters).

TABLE 15.2 Production Data for the Bioconversion of Substituted Phenols to the Corresponding Catechols

Starting Material

Yield (Total)

Yield (Adsorbed and

Compound

Added (g)

(mole%)°

Eluted) (mole%)°

3-Et-catecholb

2.0

90

82

3-Pr-catechol

1.2

81

69

3-i-Pr-catechol

2.6

91

76

3-sec-Bu-catechol

1.8

84

78

3-Cl-catechol

1.1

91

71

3-Br-catechol

2.6

84

73

"Mole % of total starting-material added. bNo standard available.

"Mole % of total starting-material added. bNo standard available.

Growing Soilless

Growing Soilless

This is an easy-to-follow, step-by-step guide to growing organic, healthy vegetable, herbs and house plants without soil. Clearly illustrated with black and white line drawings, the book covers every aspect of home hydroponic gardening.

Get My Free Ebook


Post a comment