Tables fluorides

I- is the fastest. This order parallels the decrease in basicity that occurs as one proceeds down a column of the periodic table. Fluoride ion (F ) is so slow that it is not commonly used as a leaving group. 

The trend in basicity based on rule 3 is that it increases going up the periodic table. Fluoride is smaller and more electronegative than iodide, has a greater attraction for protons, and forms a stronger bond. These factors make it more difficult to lose a proton from HF than from HI, hence, HF is a weaker acid. Clearly, the increased size of the iodine atom leads to a greater H—I bond distance and, due to the resultant decrease in internuclear electron density, a weaker bond. The acid strength increases, since the weaker I—H bond is more easily ionized, which ignores solvation effects, however, as well as product stability, which are critical to this analysis (see below)... 

Mendeleef based his original table on the valencies of the elements. Listed in Tables 1.6 and 1.7 are the highest valency fluorides, oxides and hydrides formed by the typical elements in Periods 3 and 4. 

From the tables it is clear that elements in Groups I-IV can display a valency equal to the group number. In Groups V-VII. however, a group valency equal to the group number (x) can be shown in the oxides and fluorides (except chlorine) but a lower valency (8 — x) is displayed in the hydrides. This lower valency (8 — x) is also found in compounds of the head elements of Groups V-VII. 

The following data (Table 1) for molecules, including hydrocarbons, strained ring systems, molecules with heteroatoms, radicals, and ions comes from a review by Stewart.For most organic molecules, AMI reports heats of formation accurate to within a few kilocalories per mol. For some molecules (particularly inorganic compounds with several halogens, such asperchloryl fluoride, even the best semi-empirical method fails completely. 

For a symmetric rotor molecule such as methyl fluoride, a prolate symmetric rotor belonging to the C3 point group, in the zero-point level the vibrational selection mle in Equation (6.56) and the character table (Table A. 12 in Appendix A) show that only... 

Elemental fluorine is used captively by most manufacturers for the production of various inorganic fluorides (Table 5). The market for gaseous fluorine is small, but growing. The main use of fluorine is in the manufacture of uranium hexafluoride, UF, by... 

Cryolite. Cryohte constitutes an important raw material for aluminum manufacturing. The natural mineral is accurately depicted as 3NaF AIF., but synthetic cryohte is often deficient in sodium fluoride. Physical properties are given in Table 4. 

Compounds containing fluorine and chlorine are also donors to BF3. Aqueous fluoroboric acid and the tetrafluoroborates of metals, nonmetals, and organic radicals represent a large class of compounds in which the fluoride ion is coordinating with trifluoroborane. Representative examples of these compounds are given in Table 5. Coordination compounds of boron trifluoride with the chlorides of sodium, aluminum, iron, copper, 2inc, tin, and lead have been indicated (53) they are probably chlorotrifluoroborates. 

The physical and chemical properties are less well known for transition metals than for the alkaU metal fluoroborates (Table 4). Most transition-metal fluoroborates are strongly hydrated coordination compounds and are difficult to dry without decomposition. Decomposition frequently occurs during the concentration of solutions for crysta11i2ation. The stabiUty of the metal fluorides accentuates this problem. Loss of HF because of hydrolysis makes the reaction proceed even more rapidly. Even with low temperature vacuum drying to partially solve the decomposition, the dry salt readily absorbs water. The crystalline soflds are generally soluble in water, alcohols, and ketones but only poorly soluble in hydrocarbons and halocarbons. 

Economic Aspects. Pertinent statistics on the U.S. production and consumption of fluorspar are given in Table 4. For many years the United States has rehed on imports for more than 80% of fluorspar needs. The principal sources are Mexico, China, and the Repubflc of South Africa. Imports from Mexico have declined in part because Mexican export regulations favor domestic conversion of fluorspar to hydrogen fluoride for export to the United States. 

Cobalt difluoride [10026-17-2] C0F2, is a pink solid having a magnetic moment of 4, 266 x 10 J/T (4.6 Bohr magneton) (1) and closely resembling the ferrous (Fep2) compounds. Physical properties are Hsted in Table 1. Cobalt(II) fluoride is highly stable. No decomposition or hydrolysis has been observed in samples stored in plastic containers for over three years. 

The physical properties of the halogen fluorides are given in Table 1. Calculated thermodynamic properties can be found in Reference 24. 

Bromine Monofluoride. Bromine monofluoride is red to red-brown (4) and is unstable, disproportionating rapidly into bromine and higher fluorides. Therefore, the measurement of its physical properties is difficult and the values reported in Table 1 are only approximate. The uv-absorption spectmm is available (25). 

KIFg [20916-97-6] which are both stable, white, crystalline soflds (3,94,95). These compounds dissociate at 200°C to KF and the corresponding halogen fluoride. Other salts are formed similarly (71,95—99). Some of the acids and bases of these systems are Hsted ia Table 2. 

Table 2. Acids and Bases Derived from Halogen Fluorides...

Physical Properties. Physical properties of anhydrous hydrogen fluoride are summarized in Table 1. Figure 1 shows the vapor pressure and latent heat of vaporization. The specific gravity of the Hquid decreases almost linearly from 1.1 at —40°C to 0.84 at 80°C (4). The specific heat of anhydrous HF is shown in Figure 2 and the heat of solution in Figure 3. 

Anhydrous hydrogen fluoride is an excellent solvent for ionic fluorides (Table 3). The soluble fluorides act as simple bases, becoming fully ionized and increasing the concentration of HF 2- Foi example,... 

Table 3. Solubility of Metal Fluorides in Anhydrous Hydrogen Flnoride ...

Anhydrous hydrogen fluoride is also available in cylinders, and aqueous hydrogen fluoride, either 50% or 70%, is also shipped in polyethylene bottles and carboys. Typical product specifications and analysis methods are given in Table 4. 

Production. Global hydrogen fluoride production capacity in 1992 was estimated to be 875,000 metric tons. An additional 204,000 metric tons was used captively for production of aluminum fluoride. Worldwide capacity is tabulated in Table 5 (38). Pricing for hydrogen fluoride in 1990 was about 1.52/kg (39). 

Anydrous HF for the production of aluminum fluoride. See also Table 6. 

North America accounts for about 38% of the worldwide hydrogen fluoride production and 52% of the captive aluminum fluoride production. Table 6 (38) summarizes North American capacity for hydrogen fluoride as weU as this captive capacity for aluminum fluoride production. In North America, HF is produced in the United States, Canada, and Mexico, but represents a single market, as weU over 90% of the consumption is in the United States. 

Properties. Lithium fluoride [7789-24-4] LiF, is a white nonhygroscopic crystaUine material that does not form a hydrate. The properties of lithium fluoride are similar to the aLkaline-earth fluorides. The solubility in water is quite low and chemical reactivity is low, similar to that of calcium fluoride and magnesium fluoride. Several chemical and physical properties of lithium fluoride are listed in Table 1. At high temperatures, lithium fluoride hydroly2es to hydrogen fluoride when heated in the presence of moisture. A bifluoride [12159-92-17, LiF HF, which forms on reaction of LiF with hydrofluoric acid, is unstable to loss of HF in the solid form. 

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