Chemistry, Synthesis

The commercially most interesting metal complex pigments within the azo series are those obtained from aromatic o,o -dihydroxyazo compounds, while important products within the azomethine series are nickel or copper complexes of aromatic o,o -dihydroxyazomethine compounds. 

The aromatic moieties are possibly substituted benzene or napthaline rings. In azomethine pigments, only one form of metal complex is possible. This is in contrast to azo metal complexes, which may assume either structure 31 or 32  

The nitrogen atom which is connected to the least nucleophilic aromatic moiety is always the one to serve as a ligand. As is the case with yellow and red monoazo pigments, which have been studied by three dimensional X-ray diffraction analysis (Sec. 2.3.1.1 and 2.5.1), the chelate-6-rings of azo metal complexes prefer the quinonehydrazone structure over the hydroxyazo form [4], 

The commercially interesting metal complex pigments usually contain the co-ordinative tetravalent Cu+ + or Ni+ + ions, less commonly Co++ ions. The fourth coordination site is typically occupied by a solvent molecule with a free electron pair. It may also be engaged by the second nitrogen atom of a different pigment molecule, a phenomenon which is observed in azo complexes and similar materials. In the latter case, sandwich structures are obtained [5]. The copper and nickel complexes are mostly planar molecules. 

It is important for metal complex compounds to be free from solubilizing groups in order to provide the necessary pigment characteristics. 

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H. Zollinger, Color Chemistry Synthesis, Properties and Applications of Organic Dyes and Pigments, 2nd ed., VCH, 1991. 

A.V.Topchiev Oil-Chemistry Synthesis Institute, RAS 29 Leninsky Prospect, Moscow 119991, RUSSIA -Saratov State University named after N.G.Chernyshevski 83 Astrakhanskaya Str, Saratov 410012, RUSSIA Saratov Institute of Law of RF Ministry of Home Affairs 339 Sokolovaya Str, Saratov 410034, RUSSIA E-mail SuminaEG yandex.ru, AtayanVZ info.sgu.ru... 

S.J. Shuttleworth, S.M. Allin and P.K. Sharma, Functionalised Polymers - Recent Developments and New Applications in Synthetic Organic Chemistry, Synthesis 1217-1239 7997. 

M. Lounasmaa, in Studies in Natural Produet Chemistry Synthesis (Atta-Ur-Rahman, ed.), vol. 1, p. 89. Elsevier, Amsterdam, 1988. 

Chemistry, synthesis, and biological evaluation of purine 7-A-oxides relative to nucleic acids 97H(44)573. 

Occurrence, chemistry, synthesis and cytokinin activity of l -methyl-rran.s-zeatin and its analogs (glycosylated adenine derivatives) 97H(46)659. 

Wilson, S. R. Czamik, A. W. Combinatorial Chemistry Synthesis and Application Wiley New York, 1997. 

Scheme 23. Barton s thiohydroxamate ester chemistry synthesis of alkyl pyridyl sulfides (127).

Jung G (ed) (1999) Combinatorial chemistry - synthesis, analysis, and screening. Wiley, Weinheim... 

J.R. Hanson, Applications of Chromium(H)-Salts in preparative organic chemistry, Synthesis 1974, 1. 

Scheme 18 Click chemistry synthesis of 1,4-disubstituted triazoles...

Goodman, J. M. 2000 Solutions for chemistry synthesis of experiment and calculation. Phil. Trans. R. Soc. Lond A 358, 387-398. 

Carmen Socaciu was bom in Cluj-Napoca, Romania and earned a BSc in chemistry in 1976, an MSc in 1977, and a PhD in 1986 from the University Babes-Bolyai in Cluj-Napoca, an important academic centre located in the Transylvania region. Dr. Socaciu worked as a researcher in medical and cellular biochemistry for more than 10 years, and became a lecturer in 1990 and full professor in 1998 in the Department of Chemistry and Biochemistry of the University of Agricultural Sciences and Veterinary Medicine (USAMV) in Cluj-Napoca. She extended her academic background in pure chemistry (synthesis and instrumental analysis) to the life sciences (agrifood chemistry and cellular biochemistry). Her fields of competence are directed especially toward natural bioactive phytochemicals (carotenoids, phenolics, flavonoids), looking to advanced methods of extraction and analysis and to their in vitro actions on cellular metabolism, their effects as functional food ingredients, and their impacts on health. 

Haswell, S.T., Watts, P., Green chemistry synthesis in micro reactors. Green Chem. 5 (2003) 240-249. 

HaswellS.T. VattsP., Green chemistry synthesis in micro reactors. 

Uson, R., Lagrma, A. and Vicente, J. (1977) Aryl-Gold Chemistry. Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry, 7(5), 463-496. 

Karlin, K.D. Dithiolene Chemistry Synthesis, Properties, and Applications, vol. 52. Wiley, New York (2004)... 

Messina MT, Metrangolo P, Resnati G (2000) Resolution of racemic perfluorocar-bons through self-assembly driven by donor-acceptor intermolecular recognition. In Ramachandran PV (ed) Asymmetric fluoro-organic chemistry synthesis, applications, and future directions. ACS symposium series 746. American Chemical Society, Washington DC, p 239... 

Scheme 3.1 The Medicinal Chemistry synthesis of A -3-keto-4-azasteroids.

Early process development and modification of the Medicinal Chemistry synthesis for the first kilogram-scale delivery of finasteride... 

Following preliminary assessment of the Medicinal Chemistry synthesis, the decision was made to modify the synthesis for scale-up to address some of the issues identified but, without a ready alternative for the double bond introduction, (PhSeO)20 would be used in the first scale-up to kilogram scale. 

Process development of the synthesis of iodoaniline 28 began with an improved synthesis of l-(4 -aminobenzyl)-l,2,4-triazole (6) (Scheme 4.7), which was prepared in the medicinal chemistry synthesis, albeit with poor regioselectivity (Scheme 4.1). We found that this aniline intermediate 6 could be readily prepared in three steps in >90% overall yield from 4-amino-l,2,4-triazole (30) and 4-nitrobenzyl bromide (4) based on a modified literature procedure [9]. The condensation of 30 and 4 in isopropyl alcohol followed by deamination gave the nitro... 

The original medicinal chemistry synthesis of ether 18 involved reaction of alcohol 10 with racemic imidate 17 in the presence of a catalytic amount of TfOH and furnished an approximately 1.1 1 mixture of 18 19 (Scheme 7.3) [1], We thought it worthwhile to reinvestigate this reaction with chiral imidate 67 in an effort to explore the diastereoselectivity of the etherification. 

Scheme 9.1 Final steps in the Medicinal Chemistry synthesis of taranabant 1.

With a common intermediate from the Medicinal Chemistry synthesis now in hand in enantiomerically upgraded form, optimization of the conversion to the amine was addressed, with particular emphasis on safety evaluation of the azide displacement step (Scheme 9.7). Hence, alcohol 6 was reacted with methanesul-fonyl chloride in the presence of triethylamine to afford a 95% yield of the desired mesylate as an oil. Displacement of the mesylate using sodium azide in DMF afforded azide 7 in around 85% assay yield. However, a major by-product of the reaction was found to be alkene 17, formed from an elimination pathway with concomitant formation of the hazardous hydrazoic acid. To evaluate this potential safety hazard for process scale-up, online FTIR was used to monitor the presence of hydrazoic acid in the head-space, confirming that this was indeed formed during the reaction [7]. It was also observed that the amount of hydrazoic acid in the headspace could be completely suppressed by the addition of an organic base such as diisopropylethylamine to the reaction, with the use of inorganic bases such as... 

K. Wold, K. Dwight, Solid State Chemistry - Synthesis, Structure and Properties of Selected Oxides and Sulfides. Chapman Hall, 1993. 

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