Catalyst‐Free Synthesis of Alkylpolyglycosides Induced by High‐Frequency Ultrasound

Abstract

The irradiation of concentrated feeds of carbohydrates in alcoholic solution by high-frequency ultrasound (550 kHz) induces the formation of alkylpolyglycosides (APGs). This work is distinct from previous reports in that it does not involve any (bio)catalyst or activating agent, it takes place at only 40 °C, thus avoiding degradation of carbohydrates, and it selectively yields APGs with a degree of polymerization in a window of 2-7, an important limitation of the popular Fischer glycosylation. This ultrasound-based technology proved successful with a range of different valuable carbohydrates and alkyl alcohols. The elucidation of the structure of all the produced glycosides strongly suggests that 1,6-anhydrosugars formed in situ are key intermediate species.

(Non-)Kolbe electrolysis in biomass valorization – a discussion of potential applications

“…cellulose, saccharides, furans, alcohols, aldehydes, and acids. [5][6][7][8][9][10] In recent years the electrochemical conversion of bio-derivable compounds has found growing implementation, thus enriching the portfolio of available technologies for biomass down-streaming. [11][12][13] The growing interest in electrochemistry in the context of biomass utilization and renewable electricity can be traced down to several advantages: due to fluctuations in the increased share of renewable feeds, efficient ways for the use and storage of over-produced green electricity during peak hours are required in order to ensure a steady supply.…”

Like Visiting an Old Friend: Fischer Glycosylation in the Twenty-First Century: Modern Methods and Techniques

“…The parameters that were modified included temperature (40 °C, 20 °C, and 0 °C at 40 wt.% man. under air), wt.% mannose (40% and 80% at 40 °C under air), and type of gas (air, Ar, and O 2 at 40 °C with 40 wt.% mannose) (Table 25 ) [ 54 ].…”

“…under air), wt.% mannose (40% and 80% at 40 °C under air), and type of gas (air, Ar, and O 2 at 40 °C with 40 wt.% mannose) (Table 25 ) [ 54 ].…”

“…Furthermore, the group was able to increase the concentration of mannose to 80 wt.% (Table 25 , entry 6), resulting in a mannose conversion of 73% with APGs with DPs from 2–7 at 66% yield. The space–time yield in this scenario was found to an unprecedented 876 kg m −3 h −1 [ 54 ].…”

“…The group concluded that high-frequency ultrasound allows selective activation (with no product having a methoxy group at a position other than the anomeric center) of the anomeric position of the analyzed sugars without the use of a catalyst as in traditional Fischer glycosylation [ 54 ].…”