Sucrose specific rotation

Invertase Inverts Sucrose The hydrolysis of sucrose (specific rotation +66.5°) yields an equimolar mixture of D-glucose (specific rotation +52.5°) and D-fructose (specific rotation —92°). (See Problem 4 for details of specific rotation.)... 

Invertase Inverts Sucrose The hydrolysis of sucrose (specific rotation +66.5°) yields an... 

The specific rotation ia water is [0 ] ° — +66.529° (26 g pure sucrose made to 100 cm with water). This property is the basis for measurement of sucrose concentration ia aqueous solution by polarimetry. 100°Z iadicates 100% sucrose on soHds. 

Substituent effect, additivity of, 570 electrophilic aromatic substitution and, 560-563 summary of. 569 Substitution reaction, 138 Substrate (enzyme), 1041 Succinic acid, structure of, 753 Sucralose, structure of. 1006 sweetness of, 1005 Sucrose, molecular model of. 999 specific rotation of, 296 structure of, 999 sweetness of, 1005 Sugar, complex, 974 d, 980 L, 980... 

The following Tables constitute a list of most of the known, characterized derivatives of sucrose. The names of the solvents used for measuring the specific rotations are abbreviated as follows A, acetone C, chloroform Dm, dichloromethane E, ethanol M, methanol Mf, N,N-dimethylformamide P, pyridine and W, water. 

The reaction is pseudo-first order and rate is proportional to [Sucrose], The progress of the reaction can be studied by measuring the change in specific rotation of a plane of polarised light by sucrose. Let r0, r, and r are the rotation at initially (when t = 0), at any time t and final rotation, respectively. The initial concentration a is proportional to (r0 - r, ) and concentration at any time t, (a - x) is proportional to (r0 - rt). Thus, the rate constant may be obtained as... 

Problem 1.7 The specific rotation of sucrose in presence of hydrochloric acid at 35°C was measured and is given as follows ... 

Fia. l. —Decrease with time in specific rotation at 0° of approximately 5% sucrose solutions completely and quickly inverted by invertase. Plot II corresponds to a somewhat higher acidityj than plot I. 

The result, [a] D -f-110° with an error of not more than + 2°, showed that prior to mutarotation the D-glucose was the ordinary a-form of rotation approximately - -109°, now known as a-D-glucopyranose. Sucrose, then, was an a-D-glucoside. Inspection of Fig. 1 also shows that after inversion but before mutarotation the sum of the rotations contributed by the a-D-glucose and the D-fructose remained very close to the specific rotation of 66° possessed by the original sucrose. The relationship ... 

Problem 22.40 Hydrolysis of ( + )-sucrose gives a mixture of d-( + )-glucose ([aji, = 52.7°) and o-(-)-fructose ((ajo = -92.4°) called invert sugar. Calculate the specific rotation of invert sugar. 

One mole of sucrose produces 1 mol each of glucose and fructose, and the specific rotation is one-half the sum of those of the two monosaccharides i.e. 

Sucrose is a disaccharide that is composed of a unit of glucose (acetal form) and a unit of fructose (ketal form) linked through C-1 of glucose and C-2 of fructose, i.e. a 1,2 link. In sucrose, neither glucose nor fructose can exist in open chain form because of the formation of acetal and ketal as shown below. As a result, sucrose is not a reducing sugar, and does now exhibit mutarotation. The specific rotation [a]D of sucrose is +66°. 

Hydrolysis of sucrose yields glucose and fructose with specific rotations [q ]d + 52.5° and —92°, respectively, and makes the resulting mixture laevorotatory (—). This phenomenon of sucrose is called the inversion of sucrose, and the resulting mixture is known as invert sugar, which is the main component of honey, and is sweeter than sucrose itself. 

Specific Rotations of Sucrose and of D-Fructoae in 4 Jlf Solutions of Alkali Metal... 

Hudson10 showed that the mutarotation of fructose in water at 30° is eleven times faster than that of glucose. He therefore assumed that in a sucrose solution which is undergoing very rapid inversion with invertase at that temperature, practically all of the fructose has reached equilibrium and exists as a mixture of its a and 0 forms, while the glucose is being liberated in only one form which, however, slowly passes to its a, 0 equilibrium mixture. The drop in rotation between the apparent and real curves of inversion by invertase must therefore be due almost entirely to the mutarotation of glucose. Hudson thus showed that the D-glucose liberated from sucrose by invertase had a specific rotation between [< ]d +100° and +125° and is thus most likely the a-form. 

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