Chemistry, Synthesis, Starting Materials

This is a yellow pigment, obtained by condensing 2,5-dichloro-l,4-diamino-benzenedihydrochloride with 3-iminoisoindolinone in chlorobenzene at 140°C  

A decisive step towards the development of isoindolinone pigments is credited to Geigy. Patents published in the late 1950s describe pigments with the basic structure 37, using tetrachlorophthalimide as starting material. 

The technique of perchlorinating the two aromatic rings surprisingly enhances both the tinctorial strength and the fastness properties of the product considerably. This quality increase is notably attributed to factors which are described in detail in Sec. 2.11.2. 

The methine type comprises isoindoline derivatives which, like tetrachloro-isoindolinone pigments, have only recently been described. One or usually two equivalents of a compound containing an activated methylene moiety are attached to one equivalent of isoindoline. The list of compounds featuring activated methylene groups includes cyanacetamide or heterocycles such as barbituric acid or tetrahydroquinolinedione. 

It should be noted that none of these pigments feature chlorine substitution on the aromatic system. 

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Synthesis and Properties. The synthesis of (21) follows a very straightforward route based on readily accessible starting materials and on some novel reactions ia organo—inorganic sulfur chemistry (83—85), as well as on polycondensation chemistry analogous to that utilized ia the preparation of poly(alkyl/arylphosphazenes). One preparation of (21) is as follows ... 

The majority of U(V1) coordination chemistry has been explored with the trans-ddo s.o uranyl cation, UO " 2- The simplest complexes are ammonia adducts, of importance because of the ease of their synthesis and their versatihty as starting materials for other complexes. In addition to ammonia, many of the ligand types mentioned ia the iatroduction have been complexed with U(V1) and usually have coordination numbers of either 6 or 8. As a result of these coordination environments a majority of the complexes have an octahedral or hexagonal bipyramidal coordination environment. Examples iuclude U02X2L (X = hahde, OR, NO3, RCO2, L = NH3, primary, secondary, and tertiary amines, py n = 2-4), U02(N03)2L (L = en, diamiaobenzene n = 1, 2). The use of thiocyanates has lead to the isolation of typically 6 or 8 coordinate neutral and anionic species, ie, [U02(NCS)J j)/H20 (x = 2-5). 

Chemical Modification. The chemistry and synthetic strategies used in the commercial synthesis of cephalosporins have been reviewed (87) and can be broadly divided into ( /) Selection of starting material penicillin precursors must be rearranged to the cephalosporin nucleus (2) cleavage of the acyl side chain of the precursor (2) synthesis of the C-7 and C-3 side-chain precursors (4) acylation of the C-7 amino function to introduce the desked acylamino side chain (5) kitroduction of the C-3 substituent and 6) protection and/or activation of functional groups that may be requked. 

When specifically labelled compounds are required, direct chemical synthesis may be necessary. The standard techniques of preparative chemistry are used, suitably modified for small-scale work with radioactive materials. The starting material is tritium gas which can be obtained at greater than 98% isotopic abundance. Tritiated water can be made either by catalytic oxidation over palladium or by reduction of a metal oxide ... 

The choice of reaction solvent is also of concern in the synthesis of new TSILs. Toluene and acetonitrile are the most widely used solvents, the choice in any given synthesis being dictated by the relative solubilities of the starting materials and products. The use of volatile organic solvents in the synthesis of ionic liquids is decidedly the least green aspect of their chemistry. Notably, recent developments in the area of the solventless synthesis of ionic liquids promise to improve this situation [10]. 

Most condensations of this type start with 2-aminobenzoic acid (anthranilic acid) derivatives. In an early, extensive work on the synthesis and chemistry of dianthranilides", acid chlorides 1 were used as starting materials.2... 

A possible extension of the modified Neber reaction would be the synthesis of sulfonyl-substituted 2ff-azirines following the chemistry shown in Scheme 17 [27]. Unexpectedly, the oxime derived from -keto sulfones could not be converted into the oxime tosylate. Therefore, a different route to these requisite starting materials was designed, viz., via the corresponding sulfides 30 which were then oxidized with peracid to the sulfones 31. 

As an indispensable source of fertilizer, the Haber process is one of the most important reactions in industrial chemistry. Nevertheless, even under optimal conditions the yield of the ammonia synthesis in industrial reactors is only about 13%. This Is because the Haber process does not go to completion the net rate of producing ammonia reaches zero when substantial amounts of N2 and H2 are still present. At balance, the concentrations no longer change even though some of each starting material is still present. This balance point represents dynamic chemical equilibrium. 

Our task was to develop a feasible synthesis for diamino resorcinol. From several possibilities [1-4] the resorcinol and anihne were chosen as starting materials. The diazotated aniline was coupled with resorcinol among basic conditions giving 4,6-bisphenylazo resorcinol. Hydrogenation of the latter resulted in diamino resorcinol and aniline, which could be recycled (scheme 14.2). This chemistry is well known [5-13] therefore, the research work focused on finding the optimal parameters and catalyst and finally on elaborating a process for scale-up. 

Thus far, we have discovered and demonstrated a new and effident method for the synthesis of indoles from various carbonyl compounds. This, in conjunction with the use of alkyries in the palladium-catalyzed indolization, widens the spectrum of indoles that can be prepared by these means. The simple procedure, mild reaction conditions, and ready availability of the starting materials render these methods valuable additions to indole chemistry. We next extended this method to the synthesis of the indole core of a PGD2 receptor antagonist, laropiprant 3. 

Although the synthesis of acid 3 developed by our Medicinal Chemistry colleagues proceeded in a single step from commercial starting materials the yield was modest, and there were significant safety concerns about the use of sodium hydride in DMF on a larger scale. After some experimentation it was found that use of the ester in conjunction with just 1 equiv of KHMDS as base gave a clean... 

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