Weight and Melting Point

Molecular weights (MW), melting points (m.p.), densities (d), apparent 

Chenodeoxycholic acid CDCA (3 ,7a-dihydroxy-cholanoic acid) 392.56 143 1.20 

Dehydrocholic acid DHCA (3,7,12-triketo-cholanoic acid) 402.51 237  

Density, g/cm Kip, cmVg Apparent partial specific volume of Na salt in aq. solution (43) MV, Aymolecule Apparent anhydrous molecular of Na slat in aq. solution 

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An unusual method for the preparation of syndiotactic polybutadiene was reported by The Goodyear Tire Rubber Co. (43) a preformed cobalt-type catalyst prepared under anhydrous conditions was found to polymerize 1,3-butadiene in an emulsion-type recipe to give syndiotactic polybutadienes of various melting points (120—190°C). These polymers were characterized by infrared spectroscopy and nuclear magnetic resonance (44—46). Both the Ube Industries catalyst mentioned previously and the Goodyear catalyst were further modified to control the molecular weight and melting point of syndio-polybutadiene by the addition of various modifiers such as alcohols, nitriles, aldehydes, ketones, ethers, and cyano compounds. 

SoHd epoxy resins are sometimes designated as 1-, 4-, 7-, or 9-type resins these approximate the degree of polymerization. Commercial products are designated similarly, eg, Epon 1001, 1004, 1007, and 1009 (SheU Chemical Co.). The relationship between n value, epoxy equivalent weight, and melting point is shown in Table 5. 

Fine metal particles have received much attention in recent years from the viewpoints of chemical, physical, and biological interests (1-4). They are one of the most promising advanced materials. Compared with metal oxide or metal salts, metals have the highest electric and thermal conductivity, considerably higher weight and melting point, and usually excellent catalytic properties. These properties of metals cannot be replaced by other materials. Thus, even after the rapid growth of plastic, bulk metals keep their important position as one of the most common raw materials. 

Austin, J. 1930. A Relation Between the Molecular Weights and Melting Points of Organic Compounds. J. Am. Chem. Soc. 52, 1049. 

Mackay (2000) recommends two methods, one of which uses the value of log Kow to derive solubility. The SRC program WSKOWWIN also predicts solubility from the value of log Kow (Meylan et al. 1996). Molecular weight and melting point (if known, for solids) are also inputs to WSKOWWIN. 

Until the more recent research described above, it was thought that, with one exception, crystalline alkyl ammonium clathrate hydrates were formed exclusively with the large tetra-n-butyl ammonium and tetra-isoamyl ammonium cations, with water contents of more than 50Vo by weight and melting points between 10° and 30 °C. The increased viscosity of the solutions from which these salts are crystal-... 

This part contains 64 indexes of analytical data, tabulated in numerical order, and includes all the data for chromatography, spectrophotometry, and mass spectrometry, together with indexes of molecular weight and melting point. 

The physico-chemical properties of amino acids are summarized in Table 1. This includes a wide array of measiues, from refractivity and melting point to the pKa at the amino group. Some of the parameters span a narrow range of values (e.g., the molecular weights and melting points). Other parameters differ by a factor of 100-fold or more, which include the pKas at the amino group and solubility. The AAindex database compiled by Kawashima et al. (21) is an excellent soiuce of additional information that concerns the physico-chemical properties of amino acids. 

Plan a procedure for separating 2.0 g of the mixture into its components and have the plan checked by the instructor before proceeding. A flow sheet is a convenient way to present the plan. Using solubility tests, select the correct solvent or mixture of solvents to crystallize 4-chloroaniline. Determine the weights and melting points of the isolated and purified products and calculate the percent recovery of each. T urn in the products in neatly labeled vicils. 

Recrystallize the products from the minimum quantities of hot hexane or ligroin. Isolate the crystcils, dry them, and determine their weights and melting points. Calculate the percent recovery of the crude and recrystallized products based on the 0.2 g of each in the original mixture. 

In a 25-mL Erlenmeyer flask dissolve 0.5 g of triphenylmethanol in 10 mL of acetic acid and then add to this solution 2 mL of an acetic acid solution containing 5% of chloroacetic acid and 1 % of sulfuric acid. Heat the mixture for 5 min, add about 5-6 mL of water to produce a hot saturated solution, and let the tube cool slowly to room temperature. Collect the product by filtration, and wash the crystals with 1 1 methanol-water. Once they are dry, determine the weight and melting point and then perform tests on Compounds 1 and 2 to deduce their identities. 

Table 12. Typical molecular weights and melting points of Poly(FAD-SA) ...

The table gives the molecular weight and melting point of the acid and the melting and boiling points of the methyl ester of the acid when available. A superscript on the boiling point indicates the pressure in mmHg (torr) if there is no superscript, the value refers... 

The effectiveness of stearic acid in activating vulcanization is a function of its solubility in the elastomer, molecular weight, and melting point. 

If you started with aniline, transfer the solid to a 10-mL Erlenmeyer flask and recrystallize the product from 95% ethanol (see Technique 11, Section 11.3, and Figure 11.4). Filter the crystals on a Hirsch funnel and dry them for several minutes with suction. The brominated products from either acetanilide or anisole should be crystallized using a Craig tube (Technique 11, Section 11.4 and Figure 11.6). Use 95% ethanol to crystallize the acetanilide product and hexane to crystallize the brominated anisole compound. Allow the crystals to air-dry and determine the weight and melting point. 

Analysis and Recrystallization Determine the weight and melting point of each crude product. If you know the relative amounts of benzoic acid (5) and naphthalene (7) in the original mixture, calculate the percent recovery of each compound. Recrystallize them according to the general procedures provided in Section 3.2 and determine the melting points of the purified materials. 

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