Compounds from halides

Table 2.4 Synthesis of nitro compounds from halides...

The general method for the preparation of organo-fluorine compounds from halides and sulfonates using anhydrous TBAF suffers from the fact that wherever possible an elimination reaction occurs decreasing the yield of the fluoro-substituted product. Traces of moisture present in anhydrous TBAF induce the formation of a hydroxy-substituted product. 1-Bromooctane... 

A complication to the formation of a single compound from halide displacement reactions is the ability of the main group element center to undergo redistribution reactions. Examples are given in Eqs. (166)— (169).41 45 These reactions probably account for why the complexes [Co(CO)4]2EC1 and [Co(CO)4]EC12 (E = P, As, Sb) have not been isolated.57... 

The synthesis of a great wealth of other heterocyclic compounds from halides, by carbon-heteroatom bond formation in the key step, is also an important area of organic synthesis and especially of natural product work. Recent reviews have considered key synthetic intermediates of this type946,947. Hence this section only briefly reviews the formation of some N-, O- and S-containing heterocyclic compounds that have been the targets of recent synthetic pathways. 

Oxo compounds from halides via nitrones a,/5-Ethylene aldehydes... 

Diorganomercury compounds from halides 2 RHal -> R2Hg... 

Trimethylamine oxide Oxo compounds from halides or tosylates... 

Nitrogen and sodium do not react at any temperature under ordinary circumstances, but are reported to form the nitride or azide under the influence of an electric discharge (14,35). Sodium siHcide, NaSi, has been synthesized from the elements (36,37). When heated together, sodium and phosphoms form sodium phosphide, but in the presence of air with ignition sodium phosphate is formed. Sulfur, selenium, and tellurium form the sulfide, selenide, and teUuride, respectively. In vapor phase, sodium forms haHdes with all halogens (14). At room temperature, chlorine and bromine react rapidly with thin films of sodium (38), whereas fluorine and sodium ignite. Molten sodium ignites in chlorine and bums to sodium chloride (see Sodium COMPOUNDS, SODIUM HALIDES). 

How would you synthesize the following compounds from acetylene and any alkyl halides with four or fewer carbons More than one step may be required. 

Hydrofluoride synthesis is based on the simultaneous fluorination by ammonium hydrofluoride of niobium or tantalum oxides with other metals compounds (oxides, halides, carbonates etc.) [105]. Table 13 presents some properties of ammonium hydrofluoride, NH4HF2 [51, 71]. Ammonium hydrofluoride is similar to anhydrous HF in its reactivity, but possesses some indisputable advantages. The cost of ammonium hydrofluoride is relatively low, it can be dried and handled easily, recycled from gaseous components, and its processing requires no special equipment. 

Most of the reactions of the halogens are of the oxidation-reduction type. The halogens are so reactive that they do not occur uncombined in nature and they must be made from halide compounds (salts). We shall consider briefly the preparation of the elements and then explore some of the very interesting chemistry of this family. 

Some preparations of alkene and acetylenic compounds from alkene and acetylenic starting materials can, in principle, be classified in either the monofunctional or difunctional sections for example, the transformation RCH=CHBr — RCH=CHCOOH could be considered as preparing carboxylic acids from halides (Section 25, monofunctional compounds) or preparing a carboxylic acid-alkene (Section 322, difunctional compounds). The choice usually depends on the focus of the particular paper where this reaction was found. In such cases both sections should be consulted. 

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