comparison of india and china architecture
Reducing Sugars :
Sugars that contain aldehyde groups that are oxidised to carboxylic acids are classified as reducing sugars.
Common test reagents are :
Benedicts reagent (CuSO4 / citrate)
Fehlings reagent (CuSO4 / tartrate)
They are classified as reducing sugars since they reduce the Cu2+ to Cu+ which forms as a red precipitate, copper (I) oxide.
Remember that aldehydes (and hence aldoses) are readily oxidised (review ?)
In order for oxidation to occur, the cyclic form must first ring-open to give the reactive aldehyde.
So any sugar that contains a hemi-acetal will be a reducing sugar.
But glycosides which are acetals are not reducing sugars.
A reducing sugar is any sugar that, in basic solution, forms some aldehyde or ketone. This allows the sugar to act as a reducing agent, for example in the Maillard reaction and Benedict's reaction. Reducing sugars include glucose, glyceraldehyde, lactose, arabinose and maltose. All monosaccharides which contain ketone groups are known as ketoses, and those which contain aldehyde groups are known as aldoses. Significantly, sucrose is not a reducing sugar. It is in fact known as a non-reducing sugar.
Benedict's reagent is used to determine if a reducing sugar is present. If it is a reducing sugar, the mixture will turn green/orange/red. Fehling's solution can also be used for the same purpose, as both contain copper (II) ions, which are reduced to a brick red precipitate of copper (I) oxide when the solution is heated.
A reducing sugar occurs when its anomeric carbon is free. Since sugars occur in a chain as well as a ring structure, it is possible to have an equilibrium between these two forms. When the hemi-acetal or ketal hydroxylgroup is free, it is not locked, not linked to another (sugar)molecule, the aldehyde (or keto-) form (i.e. the chain-form) is available for reducing copper (II) ions. When a sugar is oxidized its carbonyl group (i.e. aldehyde or ketone group) is converted to a carboxyl
Sugars that contain aldehyde groups that are oxidised to carboxylic acids are classified as reducing sugars.
Common test reagents are :
Benedicts reagent (CuSO4 / citrate)
Fehlings reagent (CuSO4 / tartrate)
They are classified as reducing sugars since they reduce the Cu2+ to Cu+ which forms as a red precipitate, copper (I) oxide.
Remember that aldehydes (and hence aldoses) are readily oxidised (review ?)
In order for oxidation to occur, the cyclic form must first ring-open to give the reactive aldehyde.
So any sugar that contains a hemi-acetal will be a reducing sugar.
But glycosides which are acetals are not reducing sugars.
A reducing sugar is any sugar that, in basic solution, forms some aldehyde or ketone. This allows the sugar to act as a reducing agent, for example in the Maillard reaction and Benedict's reaction. Reducing sugars include glucose, glyceraldehyde, lactose, arabinose and maltose. All monosaccharides which contain ketone groups are known as ketoses, and those which contain aldehyde groups are known as aldoses. Significantly, sucrose is not a reducing sugar. It is in fact known as a non-reducing sugar.
Benedict's reagent is used to determine if a reducing sugar is present. If it is a reducing sugar, the mixture will turn green/orange/red. Fehling's solution can also be used for the same purpose, as both contain copper (II) ions, which are reduced to a brick red precipitate of copper (I) oxide when the solution is heated.
A reducing sugar occurs when its anomeric carbon is free. Since sugars occur in a chain as well as a ring structure, it is possible to have an equilibrium between these two forms. When the hemi-acetal or ketal hydroxylgroup is free, it is not locked, not linked to another (sugar)molecule, the aldehyde (or keto-) form (i.e. the chain-form) is available for reducing copper (II) ions. When a sugar is oxidized its carbonyl group (i.e. aldehyde or ketone group) is converted to a carboxyl