Preparation of derivatives

Derivatization procedures follow the rules for the performance of organic synthetic reactions on the micro-scale. Some special requirements associated with the type of application led to some peculiarities in the performance of the reactions and to the develop- 

Substance Support material Solvent system Reference 

Thiohydantoins of amino acids Silica gel, activated at 100°C for 1 h (1) n-Heptane-l-butanol-anhydrous formic acid (10 7 3) (2) Chloroform-95% ethanol-acetic acid (100 50 15) 17 

Alditols and alditol acetates Silica gel G Benzene-ethyl acetate (1.5 1) 18 

Metabolites of 3-deoxysteroids Silica gel G Benzene followed by ethyl acetate 19 

The compound selected for a derivative should ph sical and chemical properties which will enable an absolute differentiation to be made between the individual possibilities. 

Solid derivatives are preferable, because of the ease of manipulation of small quantities in preparation and purification, as well as in the determination of constants. 

The derivative should be prepared by a reaction which gives a good yield of fairly pure product. 

The derivative should be prepared preferably by a general reaction which under the same conditions would yield a definite derivative with the other individual possibilities. This will eliminate the necessity for a series of specific reactions. 

In connection with the application of class reactions, solid derivatives are often obtained which may serve for use in the final identification work. When this is the case, the time required to complete an ang.lysis will be materiall - lessened. 

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Note. Secondary amines, etc. in Class (ii) can be identified by their derivatives (C) and (D) above, and by their picrates when these can be readily isolated. The preparation of derivatives (D) requires the dry amine, whereas water does not aifect that of derivatives (C). 

Di- and poly-halogenated aliphatic hydrocarbons. No general procedure can be given for the preparation of derivatives of these compounds. Reliance must be placed upon their physical properties (b.p., density and refractive index) and upon any chemical reactions which they undergo. 

Experimental details for the preparation of derivatives with benzoyl chloride and with 3-nitrophthalic anhydride are given in Section IV,100,2 and 7. 

Hinsberg procedure for the separation of primary, secondary and tertiary amines is given under (viii) above, and this method may be used. The following experimental details may, however, be found useful for the preparation of derivatives of primary and secondary amines. 

Preparation of derivatives. If two distinct crystaUine derivatives of the unknown have the same melting point (or other physical properties) as those of the compound described in the hterature (or in the tables), the identity of the two compounds may be assumed. Further... 

The most important use of diketene is for the preparation of derivatives of acetoacetic acid, such as acetoacetate esters, acetoacetamides, and chloroacetoacetates, which have found many uses in life sciences, dyestuffs, adhesives, and coatings. 

Preparation and Properties of Organophosphines. AUphatic phosphines can be gases, volatile Hquids, or oils. Aromatic phosphines frequentiy are crystalline, although many are oils. Some physical properties are Hsted in Table 14. The most characteristic chemical properties of phosphines include their susceptabiUty to oxidation and their nucleophilicity. The most common derivatives of the phosphines include halophosphines, phosphine oxides, metal complexes of phosphines, and phosphonium salts. Phosphines are also raw materials in the preparation of derivatives, ie, derivatives of the isomers phosphinic acid, HP(OH)2, and phosphonous acid, H2P(=0)0H. 

The L-xylosone pathway to L-ascorbic acid was never commercialized because L-xylosone was not teaddy available and was too expensive to prepare. The route, however, was valuable for L-ascorbic acid stmcture determination and for the preparation of derivatives. 

Relatively few derivatives of organic substances are suitable for use as aids to purification. This is because of the difficulty in regenerating the starting material. For this reason, we list below, the common methods of preparation of derivatives that can be used in this way. 

Aniline [62-53-3] M 93.1, f -6.0", b 68.3/lOmm, 184.4"/760mm, d 1.0220, n 1.585, n s 1.5832, pK 4.60. Aniline is hygroscopic. It can be dried with KOH or CaH2, and distd at reduced pressure. Treatment with stannous chloride removes sulfur-containing impurities, reducing the tendency to become coloured by aerial oxidn. Can be crystd from Et20 at low temps. More extensive purifications involve preparation of derivatives, such as the double salt of aniline hydrochloride and cuprous chloride or zinc chloride, or A -acetylaniline (m 114") which can be recrystd from water. 

Sulfonation with sulfur trioxide, pyridine sulfur trioxide, pyridine bis-sulfur trioxide, and dioxane sulfur trioxide, which are useful sul-fonating agents for acidophobic substances, have been applied to the thiophene seriesd At room temperature the 2-monosulfonic acid (isolated as the barium salt) is obtained in 86% yield. Higher temperatures lead to a disulfonic acid. However, sulfonation with chloro-sulfonic acid appears to be more convenient,as the sulfonyl chloride obtained can be used directly for the preparation of derivatives. 

Oxidation with potassium permanganate was also used for the preparation of derivatives with a CH3(CH2)n (n = 2,4,6,8,12) and j0-substituted vinyP - group in the 6-position from the corresponding thioxo derivatives. ... 

However, for the preparation of derivatives which contain a functional group directly attached to position 6, the application of the foregoing cyclization method is considerably limited by the availability or existence of the required derivatives of -keto acids and may also be affected by differences in their reactivity. Cyclization of thiosemicarbazones was, therefore, used for these substances only in the case of the 6-carboxylic acid (see also Section II,B,2,a). Of the other derivatives known, the 6-acetic acid ester should be mentioned. Recently some further derivatives of dioxotriazine-6-carboxylic acid were reported. ... 

Other methods of identification include the customary preparation of derivatives, comparisons with authentic substances whenever possible, and periodate oxidation. Lately, the application of nuclear magnetic resonance spectroscopy has provided an elegant approach to the elucidation of structures and stereochemistry of various deoxy sugars (18). Microcell techniques can provide a spectrum on 5-6 mg. of sample. The practicing chemist is frequently confronted with the problem of having on hand a few milligrams of a product whose structure is unknown. It is especially in such instances that a full appreciation of the functions of mass spectrometry can be developed. 

Reduction and preparation of derivatives Concentrate the aqueous mixture to 0.5 ml. Add 20 mg of sodium borohydride dissolved in 0.5 ml of ion exchange water. Let this solution stand at room temperature for 1 hour. Destroy the excess sodium borohydride by adding acetic acid until gas evolution stops. Evaporate the solution to dryness. Add 5 ml of methanol and evaporate again to dryness. 

Deoxy-sugars. Part XVII. An Investigation of the Glycal Method for the Preparation of Derivatives of 2-Deoxy-D-galactose, W. G. Overend, F. Shafizadeh, and M. Stacey, /. Chem. Soc., (1951) 992-993. 

The antitumor alkaloid ellipticine (5,1 l-dimethyl-6//-pyrido[4,3-b]carbazole) has been isolated from many species of Ochrosia and Aspidosperma. Ellipticine and its derivatives are highly active versus several experimental neoplasms, and the compound has been widely subjected to studies devoted to its total synthesis, the preparation of derivatives, and metabolism. Metabolic transformation studies with ellipticines have been conducted, using microorganisms, in vivo and in vitro... 

Rivero IA, Gonzalez T, Pina-Luis G et al (2005) Library preparation of derivatives of 1,4, 10,13-tetraoxa-7,16-diaza-cycloctadecane and their fluorescence behavior for signaling purposes. J Comb Chem 7 46-53... 

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