Metals, halides

Fluorides are prepared by (a) gas phase reactions with F or with fluorides (e.g. MoFg, SF ), (b) reaction with HF at atmospheric pressure, (c) reaction with halogen fluorides (e.g. BrF3, BrF, IF ), (e) reaction with fluorides of Se, Sb and V, (f) reaction with liquid HF and (g) reaction with other fluorinating agents. We provide some typical examples  

Essentials of Inorganic Materials Synthesis, First Edition. C.N.R. Rao and Kanishka Biswas. 2015 John Wiley Sons, Inc. Published 2015 by John Wiley Sons, Inc. 

Reaction of gaseous HF with metals, oxides, halides, etc. to yield fluorides is a route commonly employed by many workers. We illustrate this with a few examples  

Reaction of fluorine (at low pressures) with metals at temperatures around 500-600K yields fluorides. Examples of fluorides prepared in this manner are TiF, VF, CrFj, MnFj, MnF, MoF, MoF, NbF, AgF, AgF, PtF and PtF. Reactions of fluorine with oxides, halides and sulfides yields fluorides of many metals as illustrated by the following examples  

CdS to CdFj(570K) CuOtoCuF3(670K) AuClj to AuFj(770K)  

Iron(III) salts represent efficient Lewis acid catalysts frequently utilized in a very low amount to promote Friedel-Crafts acylation. Thus, 

The same catalyst (10% mol) can be utilized in the benzoylation of anisole by benzoyl chloride (BC), showing yield improvement when performed in combination with microwave irradiation. The BC conversion is 95% (with ortho/para isomer ratio 0.06) after 1 min irradiation at 165°C and 300 W power. The reaction can be applied to different activated arenes, giving products in high yields and showing the characteristics of an economical energy-saving process able to perform clean reactions in reduced time. A further advantage is the avoidance of the solvent since the aromatic substrate can replace it. 

The benzoylation of 2-methoxynaphthalene (2-MN) 4 with an equimo-lecular amount of BC in the presence of aluminum chloride (5% mol) gives producfs 5, 6, and 7 in 63 25 12 rafio (Table 3.1). With indium trichloride in place of aluminum chloride, compound 5 is obtained in a higher selectivity (88%). On increasing the temperature in the reaction with indium trichloride, the product composition is changed, and compound 6 is the predominant one (84% selectivity). Quite similar results are achieved with iron trichloride, tin tetrachloride, and zinc chloride, while in the case of antimony pentachloride and titanium tetrachloride, compound 5 is the major product. Mechanistic studies show that the reaction involves the isomerization of 5 to 7 and 6. 

Toluene as well as xylenes, mesitylene, naphthalene, and anisole are efficiently acylated in the presence of bismuth trichloride (10%-20% mol), a medium-strength Lewis acid. Moreover, bismuth trichloride being 

A further antimony derivative, namely, bis-(para-methoxyphenyl) boryl hexachloroantimonate [prepared in situ from antimony pentachlo-ride and bis-(para-methoxyphenyl)boryl chloride] can be utilized (25% mol) in the acylation of anisole and veratrole with acetone acyl enolates in 52%-88% yield. The major advantage of the method resides in the possibility of performing Friedel-Crafts acylation at room temperature in a reaction medium that can be kept almost neutral throughout the reaction, acetone being the only co-product. 

2 Perfluoroalkanoic Acids, Petfluorosulfonic Acids, and Their (Metai) Derivatives 

Metal triflates that can be easily prepared from metal halides and triflic acid at -78°C [14] show several unique properties compared with the corresponding metal halides. The use of bismuth(III) triflate allows for acylation of both activated and deactivated aromatic compounds with anhydrides and acyl chlorides [15]. Thus, the acylation of deactivated aromatics such as trifluoromethoxyben-zene, fluorobenzene, and chlorobenzene can be achieved in high yields with benzoyl chloride in the presence of bismuth(III) triflate (10% mol) without solvent. The / ara-acylation product is the most abundant in all cases (trifluoromethoxybenzene 87% yield, ortho.para 4 96 fluorobenzene 86% yield, orthoipara 0 100 chlorobenzene 89% yield, ortho para 13 87). 

Ionic liquids in combination with supercritical fluids are a versatile tool for the immobilization and recycling of homogeneous catalysts, allowing continuous Friedel-Crafts acylation reactions to be realized. The acylation of anisole with acetic anhydride is carried out in a flow system using a metal triflate immobilized in the ionic liquid 1 -butyl-4-methylpyridinium bis(trifluoro-methylsulfonyl)imide as catalyst and scCO as continuous extraction phase [22]. Different metal triflates are utilized under continuous flow conditions using high pressure yttrium triflate possesses the best balance between sufficient acidity for catalytic activity and softness to release the product and so permits a good catalyst reuse (TONs up to 190). 

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The above Born-Haber cycle represents the enthalpy changes in the formation of an alkali metal halide MX from an alkali metal (Li. Na, K, Rb. Cs) and a halogen (Fj. CI2. Br2 or I2). 

Non-meiallic halides and Co alent metallic halides give their organic derivatives. 

Alkali metals Moisture, acetylene, metal halides, ammonium salts, oxygen and oxidizing agents, halogens, carbon tetrachloride, carbon, carbon dioxide, carbon disul-flde, chloroform, chlorinated hydrocarbons, ethylene oxide, boric acid, sulfur, tellurium... 

Pentacarbonyliron Acetic acid, nitric oxide, transition metal halides, water, zinc... 

Metal halide Metal hydride Metal hydrides... 

Metal halides react with BF (33) when heated to form BX and the metal fluoride. For example,... 

From Metal Halides. The reaction of metal chlorides with alcohols can give metal chloride alkoxides (67—69), eg... 

D. L. Hildenbrand andD. D. Cubicciotti, eds.. High Temperature Metal Halide Chemistry, 1977. 

Chlorine or bromine react with benzene in the presence of carriers, such as ferric halides, aluminum halides, or transition metal halides, to give substitution products such as chlorobenzene or bromobenzene [108-86-17, C H Br occasionally para-disubstitution products are formed. Chlorobenzene [108-90-7] ... 

Chlorination of OCT with chlorine at 90°C in the presence of L-type 2eohtes as catalyst reportedly gives a 56% yield of 2,5-dichlorotoluene (79). Pure 2,5-dichlorotoluene is also available from the Sandmeyer reaction on 2-amino-5-chlorotoluene. 3,4-Dichlorotoluene (l,2-dichloro-4-methylben2ene) is formed in up to 40% yield in the chlorination of PCT cataly2ed by metal sulfides or metal halide—sulfur compound cocatalyst systems (80). 

With Acyl Halides, Hydrogen Halides, and Metallic Halides. Ethylene oxide reacts with acetyl chloride at slightly elevated temperatures in the presence of hydrogen chloride to give the acetate of ethylene chlorohydrin (70). Hydrogen haUdes react to form the corresponding halohydrins (71). Aqueous solutions of ethylene oxide and a metallic haUde can result in the precipitation of the metal hydroxide (72,73). The haUdes of aluminum, chromium, iron, thorium, and zinc in dilute solution react with ethylene oxide to form sols or gels of the metal oxide hydrates and ethylene halohydrin (74). 

Bond energies of gaseous polyvalent metal halides... 

Carbides may also be prepared, either by dhect carburizing, as in the case of steel, in which a surface carbide film dissolves into the subsuate steel, or by refractoty metal carbide formation as in die cases when one of the refractory metal halides is mixed with methane in the plasma gas. 

A signiflcairt property of the alkali metal halides is the solubility of the metals in their molten halides. Typical values of the consolute temperatures of metal-chloride melts are 1180°C in Na-NaF, 1080°C in Na-NaCl, 790°C... 

The next major commodity plastic worth discussing is polypropylene. Polypropylene is a thermoplastic, crystalline resin. Its production technology is based on Ziegler s discovery in 1953 of metal alkyl-transition metal halide olefin polymerization catalysts. These are heterogeneous coordination systems that produce resin by stereo specific polymerization of propylene. Stereoregular polymers characteristically have monomeric units arranged in orderly periodic steric configuration. 

The bromination of 4,5-j -dihydrocortisone acetate in buffered acetic acid does not proceed very cleanly (<70%) and, in an attempt to improve this step in the cortisone synthesis, Holysz ° investigated the use of dimethylformamide (DMF) as a solvent for bromination. Improved yields were obtained (although in retrospect the homogeneity and structural assignments of some products seem questionable.) It was also observed that the combination of certain metal halides, particularly lithium chloride and bromide in hot DMF was specially effective in dehydrobromination of 4-bromodihydrocortisone acetate. Other amide solvents such as dimethylacetamide (DMA) and A-formylpiperidine can be used in place of DMF. It became apparent later that this method of dehydrobromination is also prone to produce isomeric unsaturated ketones. When applied to 2,4-dibromo-3-ketones, a substantial amount of the A -isomer is formed. 

Ester eliminations are normally one of two types, base catalyzed or pyrolytic. The usual choice for base catalyzed j5-elimination is a sulfonate ester, generally the tosylate or mesylate. The traditional conditions for elimination are treatment with refluxing collidine or other pyridine base, and rearrangement may occur. Alternative conditions include treatment with variously prepared aluminas, amide-metal halide-carbonate combinations, and recently, the use of DMSO either alone or in the presence of potassium -butoxide. 

Many reactions of fluorinated organics with metal halides result in the replacement of fluorine with halogen A general route to 1,1,1-trichloro- or tribromo-fluoroalkanes involves treating primary fluoroalkyl iodides with aluminum trichloride or aluminum tribromide [74], Benzylic [75, 76] or vinylic [72] fluorine can be exchanged for chlorine when treated with aluminum trichloride... 

Metal halides can in some cases, be used to replace other atoms or groups besides fluorine with halogen Polyfluoroacyl fluorides and chlorides can be converted to fluoroalkyl iodides by simply heating the reactant in the presence of an alkali metal iodide [[Pg.382]

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