Optical rotation specific

The specific optical rotations of pure a and p o mannopyranose are +29 3° and -17 0° respectively When either form is dissolved in water mutarotation occurs and the observed rotation of the solution changes until a final rotation of +14 2° is observed Assuming that only a and p pyranose forms are present calculate the percent of each isomer at equilibrium... 

The a-carbon of glutamic acid is chiral. A convenient and effective means to determine the chemical purity of MSG is measurement of its specific rotation. The specific optical rotation of a solution of 10 g MSG in 100 mL of 2 A/HQ is +25.16. Besides L-glutamic acid [56-86-0] D-glutamic acid [6893-26-1] and the racemic mixture, DL-glutamic acid [617-65-2] are known. Unique taste modifying characteristics are possessed only by the L-form. 

Specific optical rotation values, [a], for starch pastes range from 180 to 220° (5), but for pure amylose and amylopectin fractions [a] is 200°. The stmcture of amylose has been estabUshed by use of x-ray diffraction and infrared spectroscopy (23). The latter analysis shows that the proposed stmcture (23) is consistent with the proposed ground-state conformation of the monomer D-glucopyranosyl units. Intramolecular bonding in amylose has also been investigated with nuclear magnetic resonance (nmr) spectroscopy (24). 

Sucrose, in contrast, is a disaccharide of almost universal appeal and tolerance. Produced by many higher plants and commonly known as table sugar, it is one of the products of photosynthesis and is composed of fructose and glucose. Sucrose has a specific optical rotation, of +66.5°, but an... 

A classical, and still most useful, physicochemical parameter for characterizing glycosaminoglycans is their specific optical rotation. For pure heparins from common sources, [a]80 = + 45 to + 53 ° (see Table II). The actual value depends on the relative proportions of monosaccharide constituents (that is, the L-idosyluronic acid residues make a less positive contribution than the n-glucosyluronic residues), and on the degree of sulfation of the preparation (that is, although sulfate groups may have little direct influence on the molecular rotation, they lower the value by acting as diluents ). 

Fig. 26. a Specific optical rotations for the model building blocks for core 78, interior building block 79 and peripheral unit 80 of dendrimers of type 77 b calculated average optical rotations for the doubly branching dendrimers of Oth to 4th generation c measured optical rotations in CHC13 at different temperatures and concentrations [94]... 

M Determined by HPLC analysis using DAICEL CHIRACEL AD-H (hexane/2-propanol 9 1). M Absolute configuration was determined by comparison of the sign of specific optical rotation with the reported one. idl Reaction was carried out at room temperature. t l Reaction was carried out at 0 °C. 

Dissolve 0.500 g in 1 M sodium hydroxide, and dilute to 10.0 mL with the same solvent. The specific optical rotation is —61.0° to —65.0°, calculated with reference to the dried substance. 

The specific optical rotation of bromocriptine mesilate in different solvents is given below for 20° C corrected for loss on drying. A Perkin Eliper polarimeter 241 was used, the actual concentration being 10 mg/ml. 

Activity in the field was, however, expanding. For example, in 1927 Drew and Haworth (65) obtaind a crystalline polymeric powder by the action of hydrogen chloride on the lactone of 2,3,4-trimethyl-l-arabonic acid. Citing the increase in melting point and molecular weight, and loss of specific optical rotation, they ascribed a cyclic, high polymer structure to this polyester. 

Determination of specific optical rotation of pharmaceutical substances... 

The two characteristic parameters related to optical activity of the pharmaceutical substances, namely (a) optical rotation, and (b) specific optical rotation, can be measured satisfactorily by the help of a Polarimeter as stated below ... 

DETERMINATION OF SPECIFIC OPTICAL ROTATION OF PHARMACEUTICAL SUBSTANCES... 

The specific optical rotation of a solid substance is usually determined by measuring the angle of rotation at the wavelength of the sodium D-line at a temperature of 20°C, and calculating the result with reference to a layer 1 dm thick of a solution containing 1 g of the substance per ml. It is pertinent to mention here that the specific optical rotation of a solid is always expressed to a given solvent and concentration. 

Procedure Determine the angle of rotation of the freshly prepared 4% w/v solution of adrenaline in 1 M hydrochloric acid with the help of a previously checked polarimeter. The mean value of at least five similar determinations is employed in the calculation of the specific optical rotation. 

Calculations Calculate the specific optical rotation using the following expression, namely ... 

The specific optical rotation of a large number of potent pharmaceutical substances may be determined by the above mentioned procedure but specific concentrations and method of preparation of solutions is according to the official compendium as stated in Table 19.2 below ... 

Table 19.2 Specific Optical Rotation of Some Important Official Compounds...

S.No. Substance Concentration/Preparation of Solution Specific Optical Rotation [a]p°... 

Superimposability and loss of optical activity, and (Hi) Specific optical rotation. 

How would you carry out the determination of specific optical rotation of the following official compounds (f) Adrenaline, (ii) Betamethasone,... 

Part—IV has been entirely devoted to various Optical Methods that find their legitimate recognition in the arsenal of pharmaceutical analytical techniques and have been spread over nine chapters. Refractometry (Chapter 18) deals with refractive index, refractivity, critical micelle concentration (CMC) of various important substances. Polarimetry (Chapter 19) describes optical rotation and specific optical rotation of important pharmaceutical substances. Nephelometry and turbidimetry (Chapter 20) have been treated with sufficient detail with typical examples of chloroetracyclin, sulphate and phosphate ions. Ultraviolet and absorption spectrophotometry (Chapter 21) have been discussed with adequate depth and with regard to various vital theoretical considerations, single-beam and double-beam spectrophotometers besides typical examples amoxycillin trihydrate, folic acid, glyceryl trinitrate tablets and stilbosterol. Infrared spectrophotometry (IR) (Chapter 22) essentially deals with a brief introduction of group-frequency... 

It is possible to separate the two anomeric forms of glucose by careful recrystallization from water. The two forms have different specific optical rotations (see Section 3.4.1), [aJo + 112° for a-o-glucopyranose, and [ajo + 18.7°... 

Although the majority of current pharmacopoeial methods describe the use of specific optical rotation ([a]) for the determination of stereoisomer identity and/or content, separation techniques such as HPLC and CE are now the most frequently applied technologies during drug development and for new pharmaceutical products entering the market. Indeed, Supplementary Chapter K in Volume IV of the 2004 British Pharmacopoeia (BP) deals with this specific issue [22]. It states that in future when a monograph describes an enantiomer it will include both a test for identity ([a]) and a test to control stereoisomeric purity... 

First item in a series (for example, the first carbon linked to a carboxyl group). 2. Abbreviation for alpha particle. 3. Symbol for angle of optical rotation. 4. Symbol for degree of dissociation. 5. Symbol for electric polarizability of a molecule. 6. Often with a subscript number (i) the coefficient of [A] in the numerator of the generalized rate expression. 7. Symbol for is proportional to. 8. Symbol for Napierian absorption coefficient. 9. In brackets, symbol for specific optical rotation. 

Figure 6.5 Temperature dependence of the characteristics of sodium k-carrageenan particles dissolved in an aqueous salt solution (0.1 M NaCl). The cooling rate is 1.5 °C min-1, (a) ( ) Weight-average molar weight, Mw, and (A) second virial coefficient, A2. (b) ( ) Specific optical rotation at 436 nm, and ( ) penetration parameter, y, defined as tlie ratio of the radius of the equivalent hard sphere to the radius of gyration of the dissolved particles (see equation (5.33) in chapter 5). See the text for explanations of different regions I, II, III and IV.

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