Early Preparations

Silver azide was first prepared in 1890 by Curtius [14] by passing HN, into silver nitrate solutions. Various other methods (discussed in Volume 1, Chapter 1) were developed, but the most feasible is the reaction of the readily available sodium azide with silver nitrate. 

Silver azide has a low solubility in water (variously reported as 0.001- 

008 g/liter [15-18]) and a tendency to nucleate profusely, so it normally precipitates as a fine powder. Taylor and Rinkenbach [2] reported a reduced sensitivity for finely divided silver azide, prepared by adding a 5% sodium azide solution to a 25% silver nitrate solution in stoichiometric proportions. However, later efforts were directed at producing silver azide in a coarsely granulated, free- 

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Butanediol. 1,4-Butanediol [110-63-4] tetramethylene glycol, 1,4-butylene glycol, was first prepared in 1890 by acid hydrolysis of N,]S3-dinitro-l,4-butanediamine (117). Other early preparations were by reduction of succinaldehyde (118) or succinic esters (119) and by saponification of the diacetate prepared from 1,4-dihalobutanes (120). Catalytic hydrogenation of butynediol, now the principal commercial route, was first described in 1910 (121). Other processes used for commercial manufacture are described in the section on Manufacture. Physical properties of butanediol are Hsted in Table 2. 

Low Pressure Syntheses. The majority of metal carbonyls are synthesized under high pressures of CO. Early preparations of carbonyls were made under superpressures of 1 GPa (ca 10,000 atm). Numerous reports have appeared in the Hterature concerning low pressure syntheses of metal carbonyls, but the reactions have been restricted primarily to the carbonyls of the transition metals of Groups 8—10 (VIII). A procedure for preparing Mn2(CO)2Q, however, from commercially available methylcyclopentadienyknanganese tricarbonyl [12108-13-3] and atmospheric pressures of CO has been reported (117). The carbonyls of mthenium (118,119), rhodium (120,121), and iridium (122,123) have been synthesized in good yields employing low pressure techniques. In all three cases, very low or even atmospheric pressures of CO effect carbonylation. Examples of successful low pressure syntheses are... 

Prior to the bating process, the hides are delimed with ammonium sulfate and/or ammonium chloride. Proteases are then appUed. The early preparation proposed by Rn hm was pancreatic trypsin. The use of a bating enzyme makes the hides soft and supple to prepare them for tanning. A new microbial protease, Pyrase 250 MP (82) (Novo Nordisk A/S) has been found to be a promising substitute for pancreatic trypsin [9002-07-7] which is more expensive because it must be extracted from pancreatic glands. 

A useful reaction in early preparations of parent pyridopyrimidines was the McFadyen-Stevens decomposition of tosyl hydrazides, e.g. (93) -> (3) (62JCS4094). 

An early preparation used 1 mol base in alcoholic solution as the reducing agent ... 

Many complexes containing the octahedral CrS chromophore are known (95). The early preparative work was performed by Delepine (96) and Malatesta (97), who synthesized various chromium(III) dial-... 

Some representative examples. Many crown macrocycles incorporating other heteroatom types besides ether oxygens have been synthesized. In an early preparation of this type, Lehn et al. reported a synthesis for the 04N2-system (175, diaza-18-crown-6) usingthe procedure outlined by [4.5] (Dietrich, Lehn Sauvage, 1969). 

Besides the early preparation by Gilman173 of alkynyllead compounds using sodium acetylides and triorganolead halides, and the following modification of the method174 ... 

A second field of rapid development in the l.c. of carbohydrates is in practical, preparative chromatography. Early preparative systems used large, expensive columns with low resolving power, and hence, were not extensively applied in carbohydrate research. New research is showing that various carbohydrates can be separated on the gram scale, using normal l.c. equipment and large columns home-packed with relatively... 

The selective electrophilic aromatic substitution carried out by displacement of a metallic substituent (Hg, Sn) ( F-fluorodemetallation) using [ F]p2 or [ F]AcOF remains a method of choice to introduce a fluorine atom on a specific position. In the early preparations of [6- F]fluoro-L-DOPA, the reaction of a 6-substituted mercuric derivative with [ F]acetyl hypofluorite yielded the expected compound in 11 % yield [73,74]. Reaction of a mercuric precursor, free or on a modified polystyrene support P-CH2-COOHg(DOPA precursor) allows the preparation of [ F]fluoro-L-DOPA in an overall yield up to 23 %. The polymer supports are easily prepared, require no special treatment for storage and are convenient to use in automated production [75]. 

Early preparation of oxygen involved thermal dissociation of metal oxides, notably mercury(II) oxide, which was used independently by both Priestley... 

The early preparations of 6-p F]fluoro-L-DOPA involved reaction of a... 

Submitted by MICHAEL 1. BRUCE and MICHAEL L. WILLIAMS Checked by GUY LAVIGNE and TH RESE ARLIGUIEt This tetranuclear ruthenium carbonyl hydride was described on several occasions,5 but early preparations were usually contaminated with Ru3(CO)12, giving rise to suggestions of the existence of two isomeric forms. The situation was clarified by the work of Kaesz and coworkers,6 who discovered the direct route from Ru3(CO)12 and hydrogen, which is described below. The compound is often obtained from reactions between Ru3(CO)12 and substrates containing hydrogen (hydrocarbons, ethers, alcohols, water, etc.) and by acidification of anionic ruthenium cluster carbonyls.7... 

Historical.—This process had its origin in the early preparation of sulphuric acid by the oxidation of sulphur dioxide with nitric acid, for which operation lead chambers were first introduced in 1746 by Roebuck of Birmingham. In 1793 Clement and Desormes showed that under proper conditions the nitric acid aids the oxidation, which is in the main effected by atmospheric oxygen, and the injection of steam having already been introduced in 1774 by de la Follie, the basal chemical process was much the same as to-day. Gay-Lussac s tower was first suggested by that chemist in 1827 and was first used in 1835, being introduced into Britain in 1844. J. Glover constructed his first tower at Newcastle in 1861. 

Chalcogenolato complexes of mercury can be prepared by a variety of methods. Early preparations involve the reactions of thiols with mercury cyanide,1 the reaction of mercury salts with alkali chalcogenolates, electrochemical methods,2 and the oxidative addition of dichalcogenides to metallic mercury.3 The last method is very convenient for the preparation of complexes with sterically undemanding ligands, but becomes less facile as the... 

The photochemistry of rhenium complexes occupies a prominent position in the photochemistry of transition metal complexes. Along with early preparative studies on photosubstitution of carbonyl species like Re(CO)sX, the preparation of the remarkably stable yellow complex /ac-Re(CO)3(phen)Cl foreshadowed the discovery of the a large class of related luminescent materials by Wrighton and co-workers in the 1970s [ 1 ]. As pointed out by Vogler and Kunkley, the current photochemistry of rhenium complexes is rich, spanning eight oxidation states from formal Re(0) (for example, Re2(CO)io) to formal Re(VII) (for example MeReOs) [2],... 

For a brief history of the early preparation of monodisperse polystyrene latexes, see Vanderhoff, J.W., Preprints, A.C.S. Division Org. Coatings Plastics Chem., 1964, 2A 9 (2), 223. 

Early preparations of active zinc utilized the potassium or sodium metal reduction of anhydrous zinc salts in refluxing THF or DME (Protocol l).3,8 These highly divided zinc powders displayed high reactivity towards organic halides in oxidative addition. Alkyl iodides and bromides reacted with the zinc powders at room temperature. Even aryl bromides and iodides would react to form the corresponding arylzinc iodides or bromides at refluxing... 

Williams (1948) — guide to the early preparative chemistry of cyanide complexes. 

Beryllium and aluminum show a similar relationship. Here, the ionic radius of aluminum (0.50 A) is considerably greater than that of beryllium (0.31 A), but the charge-per-unit-size values for the two ions are quite close since the charge ratio is 3/2. This time, in situations in which size-to-charge ratio is an important consideration, beryllium and aluminum should behave similarly. (Thus the major difficulties in the early preparation of beryllium compounds were not in their separation from their homologs but rather in their separation from the corresponding aluminum compounds.)... 

General Considerations. Much experimental information is available concerning the role of molybdenum in xanthine oxidase (19, 20). In early work (prior to 1970), there was much confusion in the literature because of the presence of various inactive forms of the enzyme. It is now known that both demolybdo and desulfo forms of xanthine oxidase were present in most early preparations and remain present in many current preparations as well (20, 64). 

The early preparations gave poor yields but highly efficient methods have been developed recently. Optimum yields are obtained by the method of Pino and his coworkers9 in which tris(2,4-pentanedionato)ruthenium(III) is treated with equimolar mixtures of hydrogen and carbon monoxide at moderate temperatures and pressures (140-160°, 200-300 atmospheres). However, this method is limited by the availability of the tris-(2,4-pentanedionato)ruthenium(III) which is obtained in only low yields from the readily available ruthenium trichloride hydrate. The method given here is a modification on the Pino method. 

Wishing to broaden her experience in crystallography, Crowfoot accepted an offer to join Bernal s group at Cambridge. There, she studied early preparations of vitamin Bp vitamin D, and several of the sex hormones. Finances were a problem, though, and only a substantial gift of money from her aunt enabled her to survive. 

Potassium carbonyl ferrocyanide, 2K3[Fe(CN)5C0].7H20.—The discovery and early preparation of this salt have already been described (see p. 232). It may be prepared in the laboratory by passing moist carbon monoxide over potassium ferrocyanide at 130° C. Thus —8... 

Study of the reaction mechanism of succinate dehydrogenase has. been complicated, partly because of the activation-deactivation properties of the enzyme, and partly because most of the early preparations studied had low iron content and low activities. Kinetic studies with activated, soluble preparations have led Zeylemaker et al. [215) to propose the fol-... 

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