Melting points range

Isomerization. Maleic acid is isomerized to fumaric acid by thermal treatment and a variety of catalytic species. Isomerization occurs above the 130 to 140°C melting point range for maleic acid but below 230°C, at which point fumaric acid is dehydrated to maleic anhydride. Derivatives of maleic acid can also be isomerized. Kinetic data are available for both the uncatalyzed (73) and thiourea catalyzed (74) isomerizations of the cis to trans diacids. These data suggest that neither carbonium ion nor succinate intermediates are involved in the isomerization. Rather, conjugate addition imparts sufficient single bond character to afford rotation about the central C—C bond of the diacid (75). 

Maximum use temperatures exceed 1000°C except for Si02 (>800° C) melting points range from 1450°C (Kovar) to 3660°C (tungsten). 

DistHlation is then used to separate the hydrocarbons into different products, including Hquid fuels and waxes with melting points ranging from about 45—106°C. Currently the waxes are produced in large volumes in South Africa and Malaysia, with an estimated 12,000—14,000 t consumed in the United States in 1994. Uses are similar to those for polyethylene waxes, including hot-melt adhesives and additives for inks and coatings. 

Eartial pressure of water vapor in contact. FeCh, for instance, comines with 4, 5, 7, or 12 molecules of water with melting points ranging from about 75 to 40°C (167 to 104°F). 

When heated in a capillary tube aconitic acid decomposes rather suddenly with vigorous gas evolution at a temperature which is highly dependent upon the rate of heating and the temperature at which the sample is introduced. In the literature melting points ranging from 182.5° iQ4-5° > 16 recorded. The uncrystallized aconitic acid, when introduced at 180° into a small bath provided with mechanical agitation and heated at the rate of 2-3° per minute, usually decomposed at 189-190°. The... 

Some samples were obtained with melting points ranging from 77° to 93°, but on dissolving the samples in chloroform and evaporating the solvent the values rose to 100-102°. This is not believed to be a process of purification. 

Polymer Melting point range °C Density g/cm Degree of crystallinity % Stiffness modules psi X 10 ... 

Solid compounds can have four morphic states polymorphic, pseudo-polymorphic (solvates), amorphous, and desolvated solvates. Crystals usually exhibit narrow melting point ranges and defract light under an optical microscope. When a change in the arrangement of... 

What classes of substances are expected to have sharp melting points Which ones will have extended melting point ranges Why ... 

Esterification of at least 45% of the hydroxyl groups with long chain fatty acids, e.g., stearic or behenic acid, results in a semi crystalline material (side chain crystallization). The obtained materials are characterized by melting point ranges which are approximately 10 °C lower than the comparable methyl esters. 

Isoxsuprine HCl exhibits a melting point range of 203-204°C [1], and is found to thermally decompose around 200°C [3]. 

Tabie 12 Melting point range and Rf values for a range of di- and tetraalkylimi-... 

From the discussion it is obvious that melting temperature of polyfthio-formaldehyde) depends upon method of preparation. Those melting points range... 

---