Potassium compounds alkylation

A small fraction of the hydrocarbons decompose and deposit on the catalyst as carbon. Although the effect is minute ia terms of yield losses, this carbon can stiU significantly reduce the activity of the catalyst. The carbon is formed from cracking of alkyl groups on the aromatic ring and of nonaromatics present ia certain ethylbenzene feedstocks. It can be removed by the water gas reaction, which is catalyzed by potassium compounds ia the catalyst. Steam, which is... 

Unsymmetrically substituted pentadienyl anions populate six planar conformations, which are in equilibration13 a 18. The energy barrier for a torsion in the potassium compound (R = primary alkyl) was estimated to be approximately 35 keal/mol for the 1,2-bond and 15 keal/mol for the 2,3- and 3,4-bonds. The barriers are much lower in the lithium compound. Not only the rate, but also the position of the equilibrium is greatly influenced by the cation from trapping experiments18 it was concluded that the exo-VJ anion is most stable for lithium and the exo-U form for potassium. 

It is very interesting, however, that in alkane potassium diazoate alkylations with Meerwein s reagent (triethyloxonium tetrafluoroborate, Et30+BF4) in CH2C12 suspensions or with alkyl halides in hexamethylphosphoric triamide solutions, azoxy compounds (6.4) are formed, i.e., alkylation takes place at the (3-nitrogen (Moss et al., 1972). 

Mixtures of inorganic oxygenated compounds (halide oxides or oxide sulfides) or oxygen-rich organic compounds (alkyl oxalates) with sodium (or its alloy with potassium) are shock-sensitive explosives. 

The potassium compound 19 is readily transformed into 20 (R = alkyl) by the action of alkyl halides. The products are converted into salts of alkylamines RNH2 by acidic hydrolysis50. Uses of di-t-butyl imidodicarboxylate (21) have been reviewed46. Treatment of formamide with di-t-butyl dicarbonate 22 gives the unstable formyl compound 23, which yields 21 by the action of 2-diethylaminoethylamine (equation 18)51. 

Compared to the lithium alkyls, the carbon-metal bond in the corresponding sodium and potassium compounds is more polar and thus the lower alkyl derivatives are no longer soluble in hydrocarbons nor are they volatile (262). Therefore, little has been done to elucidate any exchange reactions in which they might participate. 

The reactivity of the newly synthesized anions was studied. As expected, they can easily be protonated and alkylated, in close analogy to other silyl anions we have investigated earlier [3, 4]. Furthermore, oligosilyl anions were successfully used for the formation of interesting silicon-heteroatom bonds [9]. In a similar manner, vinylsilyl potassium compound 4b can be transmetalated into the Mg analog [10], and the respective anion can then be used as a nucleophile in the reaction... 

Recently we found that the reaction of oligosilanes with potassium alkoxides is a valuable method for the generation of oligosilyl potassium compounds [2]. Besides the generation of alkylated, arylated, and other oligosilanes, this method also permits a simple access to a-heteroatom-substituted oligosilanes. These compounds could be subjected again to the metalation reaction, and the structure and reactivity of the obtained anions were explored. 

Phenol readily couples with diazonium salts to yield coloured compounds. The latter can be nsed for the photometric detection of phenol as in the case of diazotized 4-nitroaniline. Sahcylic acid (2-hydroxybenzoic acid) can be prodnced by the Kolbe-Schmitt reaction (stndied by the density functional method ) from sodinm phenolate and carbon dioxide, whereas potassium phenolate gives the para compound. Alkylation and acylation of phenol can be carried out with aluminium chloride as catalyst methyl groups can also be introduced by the Mannich reaction. Diaryl ethers can only be produced under extreme conditions. 

Alkyl sodium and potassium compounds, R Na+ and R K4, are strong enough bases to react with ethers, such as diethyl ether (ethoxyethane), to give ethene and the ethoxide ion (reaction 4.18). This means that ethers are unsuitable solvents for the preparation of these reactive compounds. 

Reaction 1 appears to result solely in termination. In hydrogenolysis experiments with various chelates we have observed precipitation of lithium hydride in all cases at room temperature. Attempts to generate chelated LiH in situ by adding hydrogen during ethylene polymerization also caused a rapid, irreversible loss of activity. Since there is no evidence that lithium hydride can add to ethylene under moderate polymerization conditions, it is unlikely that any significant chain transfer occurs via this mechanism. Potassium alkyls readily eliminate olefin with the formation of metal hydride, and sodium alkyls do so at elevated temperatures (56). It was noted earlier that chelation of lithium alkyls makes them more like sodium or potassium compounds, so it is quite probable that some termination occurs by eliminating LiH. It is conceivable that this could be a chain transfer mechanism with more reactive monomers than ethylene because addition to lithium hydride would be more favorable. 

In a number of derivatization reactions it is advisable to replace the original counter ion by another one. As mentioned in Sects. II-6 and II-9, organolithium compounds give much better results than potassium compounds in reactions with enolizable carbonyl compounds and with sulfur, selenium and tellurium. On the other hand, alkylations with alkyl halides and with oxiranes proceed more smoothly with the potassium intermediates. Although HMPT may be used as a co-solvent, simple replacement of lithium by potassium may give similar results combination of the counter ion and solvent effects may be even better. The replacements Li+ K + and K+ Li+ are generally fast reactions in a wide temperature range (compare e.g. [161,241]) ... 

This procedure gives typical reaction conditions for the alkylation and hydroxy-alkylation of alkyl vinyl ethers via the 1-potassio- and 1-lithio derivatives, respectively. The alkylation of the potassium compounds with alkyl bromides proceeds smoothly at temperatures in the region of —40 °C. Alkylation is often accompanied by dehydrohalogenation. In the experiment described below the ratio alkylation dehydrohalogenation is high. Under similar conditions vinylpotassium H2C=CH—K gave a much lower yield of the alkylation product (1-decene) in its... 

Summary The synthesis of a,(0-bis[tris(trimethylsilyl)silyl] alkanes was achieved by the reaction of ct,(0-ditosylalkanes with tris(trimethylsilyl)silyl potassium. Reaction of these with one equivalent of potassium /er/-butoxide resulted in clean formation of monopotassium silyl anions. Addition of another equivalent of the transmetallating agent led to the formation of the dipotassium compounds in cases where the alkyl spacer contained at least three methylene units. Partial hydrolysis of the dipotassium compounds induced an intramolecular reaction yielding a cyclic silyl potassium compound. 

The organic group in these compounds has considerable carbanionic character. In general, paraffin hydrocarbons are the only suitable reaction media. Ethers are cleaved and aromatic hydrocarbons metallated. To prepare small quantities of organosodium or potassium compounds, the mercury alkyl method can be used. 

The synthetic utility of xanthates is well documented, and several recent papers reporting on new results in this field have appeared (refs. 283, 451, 541, 616, and 617). Among these is a paper describing the reaction of the halogenophthalides (438) with potassium 0-alkyl xanthates, by which 0-alkyl S-phthalidyl xanthates (440) are produced via rearrangement of the initially formed compounds (439). Other papers deal with the kinetics of the... 

Reduction of Sulfiir Compounds. Alkyl and aryl sulfoxides are reduced by BBrs to the corresponding sulfides in good yields. Addition of Potassium Iodide and a catalytic amount of Tetra-n-... 

Oxidation of side chains. Aromatic nitro compounds that contain a side chain (e.g., nitro derivatives of alkyl benzenes) may be oxidised to the corresponding acids either by alkahne potassium permanganate (Section IV,9, 6) or, preferably, with a sodium dichromate - sulphuric acid mixture in which medium the nitro compound is more soluble. 

In addition to CuCfi, some other compounds such as Cu(OAc)2, Cu(N03)2-FeCl.i, dichromate, HNO3, potassium peroxodisulfate, and Mn02 are used as oxidants of Pd(0). Also heteropoly acid salts comtaining P, Mo, V, Si, and Ge are used with PdS04 as the redox system[2]. Organic oxidants such as benzo-quinone (BQ), hydrogen peroxide and some organic peroxides are used for oxidation. Alkyl nitrites are unique oxidants which are used in some industrial... 

Potassium fluoride [7789-23-3], KF, is the most frequently used of the alkaU metal fluorides, although reactivity of the alkaU fluorides is in the order CsF > RbF > KF > NaF > LiF (6). The preference for KF is based on cost and availabiUty traded off against relative reactivity. In its anhydrous form it can be used to convert alkyl haUdes and sulfonyl haUdes to the fluorides. The versatility makes it suitable for halogen exchange in various functional organic compounds like alcohols, acids and esters (7). For example, 2,2-difluoroethanol [359-13-7] can be made as shown in equation 9 and methyl difluoroacetate [433-53 ] as in equation 10. 

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