Question

Draw the products formed when D-arabinose is treated with each reagent. (a) ${\mathbf{Ag}}_{\mathbf{2}}\mathbf{O}\mathbf{,}\mathbf{}{\mathbf{NH}}_{\mathbf{4}}\mathbf{OH}$; (b)${\mathbf{Br}}_{\mathbf{2}}\mathbf{,}\mathbf{}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}$ ; (c)${\mathbf{HNO}}_{\mathbf{3}}\mathbf{,}\mathbf{}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}$ ,

Short answer

Answer

(a.)

(b.)

(c.)

Step-by-step solution

Arabinose

Arabinose constitutes a monosaccharide comprising five carbon atoms. The different arabinoses include D-arabinose and L-arabinose.The more common form of arabinose is L-arabinose.

Oxidation of aldoses

Aldoses comprise primary and secondary alcohol and an aldehyde. These functional groups are oxidizable.Aldehydes get oxidized to carboxylic acid producing an aldonic acid.

Another oxidation is the oxidation of aldehyde and primary alcohol to a diacid termed the aldaric acid.

Treatment of D-arabinose with various reagents

(a) The treatment of D-arabinose with ${\mathrm{Ag}}_2\mathrm{O}\mathrm{and}{\mathrm{NH}}_4\mathrm{OH}$oxidizes the aldehyde group to carboxylic acids. Aldonic acids are generated from the oxidation of aldoses. The reaction can be given as:

Treatment of D-arabinose with ${\mathrm{Ag}}_2\mathrm{O}\mathrm{and}{\mathrm{NH}}_4\mathrm{OH}$

(b) The aldehyde group of the aldoses get converted to the carboxylic acid group during the reaction of D-arabinose with ${\mathrm{Br}}_2\mathrm{and}{\mathrm{H}}_2\mathrm{O}$. The reaction can be given as:

Treatment of D-arabinose with ${\mathrm{Br}}_2\mathrm{and}{\mathrm{H}}_2\mathrm{O}$

(c)The reaction of D-arabinose with and converts the aldehyde group and primary alcohol of aldoses to carboxylic acids. The reaction can be given as:

Treatment of D-arabinose with${\mathrm{HNO}}_3\mathrm{and}{\mathrm{H}}_2\mathrm{O}$