Melam

Espeseth AS, Felock P, Wolfe A, Witmer M, Grobler J, Anthony N, Egbertson M, Melamed JY, Young S, Hamill T et al (2000) HlV-1 integrase inhibitors that compete with the target DNA substrate define a unique strand transfer conformation for integrase. Proc Natl Acad Sci USA 97 11244-11249... 

Melamed J, Beaucher WN Delayed-type hypersensitivity (type IV) reactions in dental anesthesia. Allergy Asthma Proc 2007 28 477-479. 

Wangberg I, Munthe J, Pirrone N, Iverfeldt A, Bahlman E, Costa P, Ebinghaus R, Feng X, Ferrara R, Gardfeldt K, Kock Ft, LanziUotta E, Mamane Y, Mas F, Melamed E, Osnat Y, Prestbo E, Sommar J, Schmolke S, Spain G, Sprovieri F, Tuncel G. 2001. Atmospheric mercury distributions in North Europe and in the Mediterranean Region. Atmos Environ 35 3019-3025. 

Cordon-Cardo C, O Brien JP, Casals D, Rittman-Grauer L, Biedler JL, Melamed MR, Bertino JR. Proc Natl Acad Sci USA 1989 86 695-698. 

DeLellis R, Hoda R. Immunochemistry and molecular biology in cytological diagnosis. In Koss Diagnostic Cytology and Its Histopathologic Bases, 5th edition, ed. L Koss and M Melamed, pp. 1635-1680. Philadelphia Lippincott Williams and Wilkins, 2006. 

Melamine and its salts are widely used in formulations of fire retardant additives, particularly of the intumescent type (4-71. The role played by melamine structures in these additives is however not yet understood. The thermal behaviour is of paramount importance in studies of the fire retardance mechanism. It is known that melamine undergoes progressive condensation on heating with elimination of ammonia and formation of polymeric products named "melam", "melem", "melon" (8.91. The following schematic reaction is reported in the literature (10-121 ... 

While there is clear evidence that melam Is the dimer of melamine in which two s-triazine rings are connected by a NH bridge (di 6,[2,4 diamino-1,3,5-triazine]amine) (10) ... 

Hydrobromide. A complex process takes place in the first step of weight loss of melamine hydrobromide (250-400 C) as shown by the DTG curve of Figure 6. The products evolved in this step were shown to be a mixture of melamine hydrobromide (IR) and ammonium bromide (IR and X-ray). The IR spectrum of the residue (55% at 400 0 which is compared with the original salt in Figure 7, is identical with that of reference melam hydrobromide. Furthermore, the IR of the residue... 

The by-product ammonium bromide is shown to volatilise in similar conditions in TG. This is a different behaviour altogether from that of melamine in whose thermal condensation melam can be isolated with difficulty only in carefully controlled experimental conditions (11.17). Indeed melem is the condensation product most easily isolated and this led some authors to doubt that melam could be an intermediate product of the condensation of melamine to melem and melon (19.22). 

Quantitative condensation of melamine to melam on heating at 290 C in the presence of zinc chloride and acids was previously reported in the literature (20.23). The reason for limitation of the condensation process to the dimer has however not been discussed. 

Melam hydrobromide undergoes thermal degradation between 450-550 0 (2nd step, Figure 6) with complete elimination of bromine either through evolution of ammonium bromide, which is the major product, or melamine hydrobromide as shown by IR. Also a small amount of free ammonia is evolved in this step in which melon is formed as shown by the IR of the residue at 550 0 (ca. 35% of original melamine hydrobromide). 

Similarly to melamine hydrobromide, in the second step of weight loss (370-450 0, Figure 8), IR data show that melam nitrate evolves further ammonium nit rate,ammonia and melamine nitrate giving melon which decomposes completely to volatile products above 500 C. The degradation scheme is then ... 

Figure 7. IR of melamine hydrobromide (A) and of residue at 400 C (B) melam hydrobromide (by comparison with reference compound).

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