Dicy

CIE.ORINE OXYGEN ACIDS AND SALTS - DICIE.ORINE MONOXIDE, HYPOCIE.OROUS ACID, AND HYPOCIE.ORITES] (Vol 5) Calcium hydroxide hypochlorite Ca(OCl)22Ca(OIT)2 [12394-14-8]... 

Of these methods the first named was for many years the most important commercially. Dicyanodiamide ( dicy ) is prepared by heating cyanamide solution at 70-80°C. The cyanamide itself is prepared from calcium cyanamide Figure 24.5). 

If dicy is heated just above its melting point of 209°C there is a vigorous exothermic reaction results in the evolution of ammonia and the formation of some melamine together with a number of complex water-insoluble de-ammoniation products. In order to achieve a high yield of melamine in commercial manufacture the reaction is carried out in the presence of ammonia at about 300°C under pressure Figure 24.6). 

Only one melamine molecule is formed from six urea molecules, whilst three molecules of ammonia carbamate are formed. Whilst this can be recycled to urea the conversion from urea to melamine per cycle is at most 35%. Both the main route and the recycling operation involve high pressures and the low process efficiency offsets some of the apparent economic attractions of the route compared to those from dicy . 

Chemical Designations - Synonyms Dicy 3a,4,7,7a-Tetrahydro-4,7-methanoindene Chemical Formula CioHij. 

Table 12,2. Experimental conditions, mean 5 N values and diet-tissue and tissue-tissue dilTerence values (A N) of rats not subjected to water stress and/or heat stress, Diet 8 N values are those of the protein source rather than the whole diet pellets. SD = standard deviation, co-d = collagen-diet, h-d = hair-dici, f-d = flesh-diet, co-f = collagen-flesh. 

An obvious method to investigate the formation and the nature of the catalytically active nickel species is to study the nature of products formed in the reaction of complexes such as 3 or 4 with substrate olefins. This has been investigated in some detail in the case of the catalytic dimerization of cyclooctene to 1-cyclooctylcyclooctene (17) and dicy-clooctylidene (18) [Eq. (4)] using as catalyst 7r-allylnickel acetylacetonate (11) or 7r-allylnickel bromide (1) activated by ethylaluminum sesquihalide or aluminum bromide (4). In a typical experiment, 11 in chlorobenzene was activated with excess ethylaluminum sesquichloride cyclooctene was then added at 0°C and the catalytic reaction followed by removing... 

Epoxy-DICY systems, 10 454 Epoxy equivalent weight (EEW), 10 399 Epoxy ester alkyd resins, 2 165-166 Epoxy esters, 10 380-384, 443 Epoxy formulations, performance of, 10 428 Epoxy groups, 10 567 hydrolysis of, 10 358 acid-catalyzed cross-linking of, 15 171 Epoxy molding compounds (EMC), 10 373, 430 34, 458... 

DCL DDGS DEFC DICI DISI DME DMFC DOE DP DPF Direct coal liquefaction Distillers dried grains with solubles Direct ethanol fuel cell Direct-injection compression ignition Direct-injection spark ignition Dimethylether Direct methanol fuel cell Department of Energy (USA) Dynamic programming Diesel particulate filter... 

As a final example, we consider torsional isomerism in 1,2-diamino- 1,2-dicy-anoethylene (DADCE) which is known to be a precursor in the evolutionary synthesis of nucleic acids128 Some torsional isomers of DADCE are shown below ... 

That being said, it must be recognized that the evidence that the (V-acy I isourea is the precursor of the 2-alkoxy-5(4//)-oxazolone is only circumstantial because experiments starting from the former have yet to be achieved. The oxazolone could theoretically come from the symmetrical anhydride. The latter generates 2-alkoxy-5(4//)-oxazolone in the presence of tertiary amines (see Section 4.16) even dicy-clohexylcarbodiimide (DCC) was basic enough to generate 2-t< rt-butoxy-5(4 )-oxazolone from Boc-valine anhydride. However the weight of evidence points to O-acylisourea as the precursor of the 2-alkoxy-5(4//)-oxazolone. In the absence of. V-nucleophile, such as in the preparation of esters, the major precursor of product is the symmetrical anhydride.7,8... 

FIGURE 7.10 Formation of the succinimido ester of IV-succinimidoxycarbonyl-P-alanine by reaction of three molecules of IV-hydroxysuccinimide (HONSu) with one molecule of dicy-clohexylcarbodiimide.25 The first molecule (N1) reacts to form the O-succinimido-isourea. The second molecule (N2) ruptures the ring by attack at the carbonyl, generating a nitrene that rearranges to the esterified carboxyalkyl isocyanate. The third molecule (N3) attacks the carbonyl of the latter. R3 = R4 = cyclohexyl SuN- = succinimido. 

Chen and co-workers utilized the chiral bifunctional catalysts to directly access vinylogous carbon-carbon bonds via the asymmetric Michael addition of a,a-dicy-ano-olefms to nitro-olefms [102]. The scope of the reaction was explored with a variety of substituted a,a-dicyano-olefins and P-substituted nitro-olefms (Scheme 50). The authors propose the catalysf s tertiary amine functionality depro-tonates the cyano-olefm, activating the nucleophile to add to the -face of the pre-coordinated nitro-olefm. 

Synonyms HMDI hydrogenated MDI dicy-clohexylmethane-4,4 -diisoq anate bis(4-isocyanaloq clohexyl)methane hydrogenated MDI... 

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