Lead halides fluorination

The heat of reaction may decompose phosphorus acid to phosphine, which may ignite spontaneously or explode. It is decomposed by alcohols, producing alkyl halides. The reactions of phosphorus trichloride with acetic acid, nitric acid, nitrous acid, and chromyl chloride can produce explosions. It may ignite or react violently with dimethyl sulfoxide, lead dioxide, fluorine, hydroxyl amine, and iodine monochloride (Mellor 1946, Suppl. 1948 NFPA 1997). Its vapors bum to incandescence when heated with alkali metals. 

Patents describe the synthesis of diamonds by contacting diamond powder as crystal seeds at about 700 to 1400 K with Pb(C2H5)4 at a partial pressure of 10 to 10" bar [872, 877, 881]. Reaction of Pb(C2H5)4 with halogen, e.g., fluorine or halogen compounds. Is claimed to give lead halide glass preforms for low-loss optical fibers [904]. 

Electrochemical fluorination in anhydrous hydrogen fluoride (Simons process) involves electrolysis of organic compounds (ahphatic hydrocarbons, haloalkanes, acid halides, esters, ethers, amines) at nickel electrodes. It leads mostly to perfluori-nated compounds, but is accompanied to a high extent by cleavage and rearrangement reactions. The mechanism of the formation of carbocations according to Eq. (1) and Scheme 1 is assumed... 

Fluorination of vinorelbine was thus performed in super acid medium (HF-SbFs). A super electrophilic agent, such as a chloromethyl or a Br+ cation is generated in s/fu from a chloromethane (CHCI3, CCI4) or from N-Bromo Succinimide (NBS). It is able to abstract a hydrogen from the protonated alkaloid, leading to a cation that can be trapped by an halide anion present in the medium [105,106], Difluorination remarkably occurs selectively at C-4 of the clavamine fragment (Fig. 37) [105]. 

Dehydrohalogenations at two adjacent carbon atoms lead to compounds with C = CorCsC bonds and arc an important route to fluorinated alkencs and alkynes. Some dehydrohalogenations occur spontaneously, others require elevated temperatures, and the majority occur in a basic medium which takes up the eliminated hydrogen halide.1 4 In addition to aqueous or alcoholic alkalis, organic bases such as triethylamine are often used for this purpose. 

Among the derivatives of halide-substituted alcohols the fluoroalkoxides are of special interest. The presence of peripheral fluorine atoms enables the secondary M...F interaction and filling of the coordination sphere of the metal, which leads to an unusually high volatility. These compounds are described in the review by Willis [1749]. 

Fluorine Phosphorus halides Iodine chloride Phosphorus trichloride Lead(IV) oxide Non-metal halides Nitric acid Phosphorus halides Selenium dioxide Phosphorus trichloride Sodium peroxide Non-metal halides... 

The ionic model is of limited applicability for the heavier transition series (4d and 5d). Halides and oxides in the lower oxidation states tend to disproportionate, chiefly because of the very high atomisation enthalpies of the elemental substances. Many of the lower halides turn out to be cluster compounds, containing metal-metal bonds (see Section 8.5). However, the ionic model does help to rationalise the tendency for high oxidation states to dominate in the 4d and 5d series. As an example, we look at the fluorides MF3 and MF4 of the triad Ti, Zr and Hf. As might be expected, the reaction between fluorine gas and the elemental substances leads to the formation of the tetrafluorides MF4. We now investigate the stabilities of the trifluorides MF3 with respect to the disproportionation ... 

Table 10. Fluorination of Benzyl Halides with Lead(II) Fluoride/ Sodium Bromide ...

---