Sorensen method

The Sorensen method of amino acid synthesis uses a modification of the malonic ester synthesis. In this modification an N-protected malonic ester is alkylated, hydrolyzed and decarboxylated to give an a-amino acid, as shown in equation 77. 

Other examples of the reaction are the cyanoacetic ester synthesis, in which Z is COOEt and Z is CN (as in the malonic ester synthesis, the product here can be hydrolyzed and decarboxylated), and the Sorensen method of amino acid synthesis, in which... 

I. Two liters of water are kept for a week on a hot plate at about 95°C, with continuous replacement of the evaporated water. Every day five drops each of the following solutions are added a) 16.9 g. of Ca(N03)a In one liter of CO -free water, b) 5.84 g. of KHgPO (Sorensen method for enzyme studies) in one liter of COg-free... 

This very widespread reaction is used in the assimilable nitrogen assay for assessing the potential fermentability of must and wine according to the Sorensen method, or formaldehyde titration (Ri = R2 = H). In a cold, aqueous phase, the condensation reaction stops at the carbinolamine stage,... 

The above method, due to Sorensen, is of great importance in following the course of hydrolysis of proteins by enzymes (p. 516). For example, if the protein and its hydrolysis are represented thus ... 

Only Sorensen s method is employed in the foltowing experiments. The Student should therefore first acquaint himself with the theory of the estimation of glycine (p. 463),... 

As just pointed out, the acidity or basicity of a solution can be described in terms of its H+ concentration. In 1909, Suren Sorensen (1868-1939), a biochemist working at the Carlsherg Brewery in Copenhagen, proposed an alternative method of specifying the acidity of a solution. He defined a term called pH (for power of the hydrogen ion ) ... 

For many purposes, especially when dealing with small concentrations, it is cumbersome to express concentrations of hydrogen and hydroxyl ions in terms of moles per litre. A very convenient method was proposed by S. P. L. Sorensen (1909). He introduced the hydrogen ion exponent pH defined by the relationships ... 

At this stage it should be pointed out that the original definition of pH = —log cH (due to Sorensen, 1909 and which may be written as pcH) is not exact, and cannot be determined exactly by electrometric methods. It is realised that the activity rather than the concentration of an ion determines the e.m.f. of a galvanic cell of the type commonly used to measure pH, and hence pH may be defined as... 

W. R. Sorensen and T. W. Campbell, Preparative Methods of Polymer Chemistry, Wiley-Interscience, New York, 1961, p. 74. 

K. C. Nicolaou and E. J. Sorensen, in Classics in Total Synthesis, Targets, Strategies, and Methods, VCH, Weinheim, 1996. 

By plotting the left-hand side of eqn. 2.65 against to and extrapolating back to to = 0 the intercept at to = 0 gave the value of J lgci/Ag = 0.2225 V at 25° C20 (cf., 0.2223 V21). Once E° is known, the measurement of E as a function of to provides an important method for determining molal ionic activity coefficients and a paH scale with the above type of cell, which permits a comparison with the Sorensen psH scale (cf., p. 33). 

M. Pingel, A. Volund, E. Sorensen, and A. R. Sorensen, Assessment of insulin potency by biological and chemical methods, in Hormone Drugs, U.S. Pharmacopeial Convention. Rockville, MD, 1982, pp. 200-207. 

Sorensen and Haugaard147 showed that by a suitable fractionation of crystalline albumin there could be obtained a series of fractions which, although crystalline, varied widely in their properties, particularly in regard to their carbohydrate contents. The most soluble fraction contained about fifty times as much carbohydrate as the least soluble. In most of these studies the carbohydrates were estimated by modification of the orcinol colorimetric method of Tillmans and Philipi181 which could... 

Sorensen (1993) Method for isolation and purification of enzyme-antibody conjugates. US Patent No. 5,266,686. 

Sorensen s method. The amino-acid is condensed with formal dehyde and the substance produced is now a sufficiently strong acid to be titrated. 

Sorensen is usually considered to be the first to have realized the importance of hydrogen ion concentration in cells and in the solutions in which the properties of cell components were to be studied. He is also credited with the introduction of the pH scale. Electrochemistry started at the end of the nineteenth century. By 1909, Sorensen had introduced a series of dyes whose color changes were related to the pH of the solution, which was determined by the H+ electrode. The dyes were salts of weak acids or weak bases. He also devised simple methods for preparing phosphate buffer solutions covering the pH range 6-8. Eventually buffers and indicators were provided covering virtually the whole pH range. 

Jamali, B., Theill, G. C., and Sorensen, L.-L. (2004). Generic, highly selective and robust capillary electrophoresis method for separation of a racemic mixture of glitazone compounds. ]. Chromatogr. A 1049, 183-187. 

Marques, P., Remy, C., and Sorensen, C.M. (2005) Monolithic zeolite coated structures and a method of manufacture. US Patent 6,935,551. 

Sorensen and Andersen in 1908 synthesised proline by the sodium phthalimidomalonic ester method, a yield of about 80 per cent, being obtained. Sodium phthalimidomalonic ester is condensed with trimethylene bromide,... 

Manes, L. A new method of statistical thermodynamics and its application to oxides of the lanthanide and actinide series, in Non-stoichiometric Oxides (ed. Sorensen, O. T.), Academic Press, New York, Chapt. 3, p. 99 (1981)... 

There are also other methods for measuring hydrogen ion concentration, for instance, Sorensen s (psH) unit or the activity coefficient unit (paH), based on emf measurements Refs l) L. Michaelis, Die Wasserstoffionen-Konzentration, translated from the 2nd German edition (1922) by W.A. Perlzweig and published by Williams Wilkins, Baltimore (1926) 2)... 

K. 2004. Control of seed-borne pathogens on vegetables by physical seed treatment methods. In Lammerts van Bueren, E.T., Ranganathan, R. and Sorensen, N. (eds) Proceedings of the First World IPOAM/ISF/FAO Conference on Organic Seed - Perspectives, Challenges and Opportunities. Rome, Italy, 5-7 July 2004. IFOAM, Bonn. pp. 177. 

The development of the chemistry of organometallic compounds containing the pentamethylcyclopentadienyl ligand has been hampered by the lack of a simple, high yield synthesis of 1,2,3,4,5-pentamethylcyclopentadiene (14). We have recently expanded the method first reported by Sorensen et al. (15) to a large scale preparation which follows Scheme 1 (16). This procedure is applicable... 

LK Sorensen, BM Rasmussen, JO Boison, L Keng. Simultaneous determination of 6 penicillins in cows raw milk by a multiresidue high-performance liquid chromatographic method. J Chromatogr B 694 383-391, 1997. 

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