Alkaline degradation dehydration reactions

Lactulose is unstable in alkaline solution, degrading by alkaline peeling and /3-elimination reactions to yield galactose, isosaccharinic acids, and other acid products (Corbett and Kenner 1954). Amines can bring about dehydration and degradation reactions (Hough et al. 1953). Lactulose is similar to sucrose in humectant properties (Huhtanen et al. 1980). 

Deoxy-D-glycero-hexo-2,3-diulose is a typical product of degradation and 4-0-substituted derivatives of fructose (e.g. lactulose, which arises by isomerisation of lactose). 1,2-Enolisation of 4-deoxy-D-g lycero-hexo-2,3-diulose yields, via the appropriate l-ene-l,2-diol, unstable 4-deoxyhexos-3-ulose, which splits into formic acid and 1,2-enediol of 3-deoxy-D-glycero-pentulose in neutral or alkaline solutions by a reverse Claisen condensation mechanism. This sugar can be oxidised to 3-deoxy-D-glycero-pentos-2-ulose or may dehydrate to form 3,4-dideoxypentosulose (Figure 4.32). Other reaction products are isosaccharinic acids. 

Butylation of phenylacetonitrile with aqueous NaOH, as shown in Scheme 25, proceeds faster by use of high DF (>0.5) anion exchange resins.The strongly alkaline conditions degrade the quaternary ammonium ions of the catalyst. Catalyst (64) (1% DVB) is active for alkylation of phenylacetonitrile and benzyl phenyl ketone, and for Williamson ether synthesis, and it is much more stable in base than AERs. AERs in OH form are catalysts for dichlorocyclopropane syntheses from alkenes, chloroform and solid sodium hydroxide, and for dehydration of amides to nitriles. AERs in the appropriate hydroxide, acetate, or cyanide form are catalysts for aldol condensations, Michael reactions, Knoevenagel condensations, cyanoethylations and cyanohydrin syntheses. " ... 

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