INDEX carbonate esters

Of the 3 possible types of peroxy carbonate esters-dialkyl monoperoxy carbonates, dialkyl diperoxycarbonates and dialkyl peroxydicarbonates-, the latter are by far the least stable group. Several of the 16 alkyl and substituted-alkyl esters prepared decomposed violently or explosively at temperatures only slightly above the temperature of preparation (0-10°C), owing to self-accelerating exothermic decomposition. Several were also explosive on exposure to heat, friction or shock [1], Amines and certain metals cause accelerated decomposition of dialkyl peroxydicarbonates by a true catalytic mechanism [2], Individually indexed compounds are ... 

In eadier Hterature carbonochloridic esters are referred to as chloroformates or chlorocarbonates because of the stmctural parallel with formic acid [64-18-6]., chloroformic acid, and carbonic acid. Before 1972, chloroformates were indexed in Chemicaly4bstracts, Eighth Collective Index, under formic acid, chloroesters whereas, in the Ninth Collective Index (Dec. 1990), they are referred to as carbonochloridic acid esters. Table 1 fists the common names of carbonochloridates or chloroformates, the CAS Registry Numbers, and the formulas. 

Carbonates are indexed in Chemicaly hstracts under carbonic acid, esters. Symmetrical diesters have the prefix di or bis. Unsymmetrical diesters are listed with the two radicals following each other. For example, ethyl phenyl carbonic diester is C2H OCOOC H. Table 6 Hsts commonly used carbonates, their Chemicaly hstracts Service Registry Number, and formulas. 

Aromatic carbon content cannot be directly determined from 13C NMR spectrometry because it overlaps with olefinic carbon. Aromatic and olefinic hydrogens can be resolved in H NMR spectrometry, but the chemical shifts of methine hydrogens on esters of secondary alcohols overlap with chemical shifts of olefinic hydrogen in the NMR spectra of fulvic acids. The ring content (0) is a difference determination between the index of hydrogen... 

Compound A (C4H602) has an index of hydrogen deficiency of 2. With two oxygen atoms and a peak in the infrared at 1760 cm-1, it is likely that one of the elements of unsaturation is the carbon-oxygen double bond of an ester. The H NMR spectrum contains a three-proton singlet at 8 2.1 ppm, which is consistent with a CH3C unit. It is likely that compound A is an acetate ester. 

Record the refractive indexes of the last two fractions ( d = 1-4410), and analyze them by vapor-phase chromatography. Only minor impurity peaks should show on the VPC trace at low attenuation, with the ester peak off-scale. Obtain an infrared spectram of a 5 percent solution of the final fraction in carbon tetrachloride. Isomerization of the ring to a terminally unsaturated straight chain is much less likely than with the cyclopropane ring. Check for absorption in the medium-strength 3085 cm and 3030 cm vinyl C—H stretching bands vinyl C—bending bands tend to be obscured by other features. 

The electrophilicity index also accounts for the electrophilic activation/deactivation effects promoted by EW and electron-releasing substituents even beyond the case of cycloaddition processes. These effects are assessed as responses at the active site of the molecules. The empirical Hammett-like relationships found between the global and local electrophilicity indexes and the reaction rate coefficients correctly account for the substrate selectivity in Friedel-Crafts reactions, the reactivity of carbenium ions, the hydrolysis of esters, the reactivity at the carbon-carbon double bonds in conjugated Michael additions, the philicity pattern of carbenes and the superelectrophilicity of nitronium, oxonium and carboxonium ions. This last application is a very promising area of application. The enhanced electrophilicity pattern in these series results from... 

Properties White, crystalline powder readily ester-ified by common organic acids. Bp 276C (30 mm Hg), mp 262C, refr index 1.54—1.56 (20C), d 1.399 (25/4C). Unaffected when boiled with dilute caustic alkali. Soluble in water slightly soluble in alcohol insoluble in benzene, carbon tetrachloride, ether, and petroleum ether. Combustible. 

Properties Yellowish or brownish liquid penetrating odor. D 0.903-0.960, refr index 1.486 (20C). Soluble in alcohol, ether, chloroform, acetone, benzene, and carbon disulfide. Combustible. Chief constituents Pinene, camphene, bomeol, and esters of bomeol and valeric acid. 

From the above lists, there is a natural trade-off between viscosity index and pour point, e.g. by increasing the linearity of the ester, the viscosity index improves but the pour point increases. Esters made from mixtures of normal and branched acids with the same carbon number have viscosity indices between those of the normal and branched acid esters. But their pour points are lower than those esters formed separately from either branched or normal acids. 

Simple alkyl esters also proved virtually inactive. Consequently, the 17/3-chloromethyl ester was held constant and 17a-carbonates with different substituents on the steroid skeleton were varied for further investigation. Loteprednol etabonate, and some of the other soft steroids, provided a significant improvement of the therapeutic index determined as the ratio between the anti-inflammatory activity and the thymus involution activity (114, 117,118). Furthermore, binding studies using rat lung cytosolic corticosteroid receptors showed that some of the compounds approach and even exceed the binding affinity of the most potent corticosteroids known. 

The new approach has been termed The Mesogenic Index (MI) and has successfully been applied to 23 copolymer systems in which the critical compositions for mesophase formation have been established by means of varying constituent monomer concentrations. It is also consistent in predicting liquid crystalline behaviour in several hundred main-chain polymer systems containing amide, ester, carbonate, ether and urethane groups. 

Ethyl orthoborate has a boiling point of 120°, a density of 0.86426, and a refractive index (n ) of 1.3721. It is readily hydrolyzed to ethanol and orthoboric acid. The ester may be analyzed for boron by dissolving a weighed sample in water, adding mannitol (about ten times the weight of sample taken), and titrating the boric acid to the phenolphthalein end point. This determination works best if the solution is protected from atmospheric carbon dioxide in the region of the end point. 

In the analysis of compounds which form an homologous series, for example, the methyl esters of saturated fatty acids, there is a linear relationship between the logarithm of the retention time and the number of carbon atoms. This can be exploited, for example, to identify an unknown fatty acid ester in a fat hydrolysate. A widely used system in this context is the Retention Index (RI) which is based on the retention of a compound relative to n-alkanes. The compound is... 

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