Consider the following statements about sucrose. 1\. Hydrolysis of sucrose with dilute acid yields an equimolar mixture of D-glucose and D-fructose 2\. Acid hydrolysis of sucrose is accompanied by a change in optical rotation 3\. In sucrose, the glycosidic linkage is between \(\mathrm{C}-1\) of glucose and \(\mathrm{C}-2\) of fructose 4\. Aqueous solution of sucrose exhibits mutarotation Which of the statements are correct? (a) 1 and 2 only (b) 2 and 3 only (c) 1,2 and 3 (d) 1,3 and 4

Understanding the hydrolysis of sucrose is fundamental in biochemistry. This process involves breaking down sucrose, a disaccharide, into its component monosaccharides with the aid of water and usually an enzyme or an acid. Sucrose is composed of one molecule each of glucose and fructose. During hydrolysis, the bond between these two sugars, known as a glycosidic linkage, is cleaved, yielding an equimolar mixture of D-glucose and D-fructose. This reaction not only plays a crucial role in digestion but also provides a clear example of how complex sugars are broken down into simpler forms that can be utilized by the body as an energy source.

Interestingly, this reaction can be observed when sweetening a cup of tea with sugar which is sucrose. Over time, particularly under acidic conditions or heat, the tea may become less sweet as the sucrose is hydrolyzed, decreasing its sweetening power as glucose and fructose are not as sweet as sucrose.

The concept of optical rotation is pivotal when analyzing sugars. Most sugars can rotate the plane of polarized light, which is a property called optical activity. This rotation can be either to the right (dextrorotatory) or to the left (levorotatory), depending on the sugar structure. Because glucose and fructose, the products of sucrose hydrolysis, rotate polarized light differently than sucrose itself, the overall optical rotation of the solution changes after hydrolysis.

This characteristic is not only fascinating but also of practical importance, as it allows chemists and biochemists to measure the concentration of sugars in a solution using polarimetry. This technique is commonly used in industries like food processing and pharmaceuticals where precise sugar measurements are crucial.

The glycosidic linkage is a type of covalent bond that connects two sugar molecules in carbohydrates. In sucrose, this particular bond is between the carbon-1 (C-1) atom of glucose and the carbon-2 (C-2) atom of fructose. The nature of this bond defines the properties of disaccharides, such as their ability to be hydrolyzed and their behavior in water. Other disaccharides have different glycosidic linkages, which determines whether they are reducing or non-reducing sugars, a characteristic that impacts their reactivity and how they are metabolized by the body.

Breaking down these glycosidic linkages is a critical step in digestion, emphasizing the importance of enzymes like sucrase that facilitate this process. Without the ability to break these bonds, people would not be able to derive energy from many common dietary carbohydrates.

Mutarotation is a phenomenon observed in carbohydrates where the optical rotation of a sugar solution changes over time. It occurs when an aldose or ketose sugar in aqueous solution interconverts between its alpha and beta anomeric forms, which have different optical rotations. The process is facilitated by the presence of an aldehyde or ketonic group capable of forming rings with the sugar molecule.

In the case of sucrose, because it possesses a non-reducing character due to its acetal bond between the glucose and fructose units, it cannot open up to form a free aldehyde or keto group. Thus, sucrose in aqueous solution does not undergo mutarotation. This distinguishing feature separates it from other sugars, such as glucose, which freely mutarotates in solution, transitioning between alpha and beta forms.