Glucose reaction with hydroxide ions

Additional tests with ammonium compounds were performed to address the effect of ammonium ion (see Fig. 8). It is clear that the catalyst inhibition was not based only on the presence of ammonium ion. Ammonium carbonate showed the largest inhibition of the glucose hydrogenation reaction, while chloride and hydroxide had lesser effects. Ammonium nitrate caused no apparent inhibition on glucose conversion. A similar lack of effect was shown with potassium nitrate. In the case of ammonium nitrate, the glucose conversion mechanism was affected, so that the sorbitol yield was reduced by about 20%, but numerous byproducts and overreaction products (lower molecular weight polyols) were evident. 

Whether these alkaline-earth metal ions are capable of directing the course of the transformation is at present unclear. Kusin reported that, when D-glucose reacts in calcium hydroxide solution at 25°, no D-fructose appears, whereas sodium hydroxide brings about formation of D-fructose under the same conditions of time and temperature. However, this claim is contrary to the findings of Lobry de Bruyn and Alberda van Ekenstein, Sowden and Schaffer, and Topper and Stetten, all of whom isolated D-fructose from the reaction of D-glucose with calcium hydroxide under comparable conditions. 

Further studies of the formose reaction have been reported. Alkaline-earth metal hydroxides initiated zero-order reactions at intermediate conversions of formaldehyde, and the formation of glyceraldehyde or tetroses and pentoses, etc., from formaldehyde in the presence of calcium hydroxide depended on whether or not glycolaldehyde was present. Self-condensation of formaldehyde in the presence of alkaline-earth metal hydroxides has also been studied in the absence and in the presence of a co-catalyst such as D-glucose and in the presence of glycolaldehyde. Self-condensation of formaldehyde in the presence of lead(ii) oxide appears to involve a soluble complex in which the lead atom co-ordinates with the carbonyl oxygen atom of formaldehyde. " The catalytic functions of calcium ion species in a homogeneous formose reaction and the distribution of products in a photochemical formose reaction have been investigated. 

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