Alkylation and Arylation

Alkylation and arylation. The homolytic a-oxyalkylation of heteroaromatic bases using alcohols and ethers as radical sources has been studied. Although detailed experiments were chiefly concerned with quinoline and quinoxaline, benzothiazole was shown to yield 2-dioxanylbenzothiazole (40%) under the standard conditions.  

The reactivity of benzothiazole (and its 2-methyl and 2-chloro-derivatives) towards phenyl radicals has been studied by the decomposition of benzoyl 

Alkylation and Arylation. The 5-methylation of thioamides by diazomethane is catalysed by silica gel. 5-Phenyl derivatives of thiobenzanilides are obtained in high yield by radical arylation with nitrosoacetanilide or phenylazotriphenyl-methane. Thiols are made from alkyl (or cycloalkyl, or aralkyl) halides by their reaction with dimethylthioformamide and treatment of the imidium ester with methanol other methods of hydrolysis lead to side-reactions, giving impure products. Mono- and bi-protic thiocarboxamides condense with ethyl bromo-cyanoacetate and one equivalent of NaOEt with spontaneous separation of sulphur and the formation of ff-amino-cr-cyano-acrylates, as shown in reaction (5). The 

4-Benzoquinone and thioacetamide react by Michael addition at the sulphur atom with an excess of quinone, oxidation and cyclization occur, to give (76). At lower quinone ratios, acetonitrile is eliminated from the Michael adduct to give 

Kandror, I. O. Bragina, and R. Kh. Freidlina, Dokl.Akad. Nauk SSSR, 1979, 249, 867 Chem. 

Hattori, T. Takido, and K. Itabashi, Nippon Kagaku Kaishi, 1979, 105 Chem. Abstr., 1979, 90, 

Gotschi, and A. Eschenmoser, Helv. Chim. Acta, 1971, 54, 710. 

Tellurolates can be easily alkylated and, under suitable conditions, arylated to produce symmetrical and unsymmetrical diorgano tellurium (p. 387) and alkyl aryl tellurium (p.409) compounds. Examples of alkylating agents are primary n-alkyl bromides and iodides, secondary alkyl bromides, dimethyl sulfate, allyl bromides chlorodifluoro-methane , dichloroiodomethane , methyl m-bromoalkanoates 3-halopropanoic 

Irgolic Organic Tellurium Compounds with one Te,C Bond 

The products formed from the reactions of tellurolates with a,aj-dihaloalkanes or a, u-dihaloalkenes are dependent on the chain length of the dihalide. 

The reaction of sodium 4-ethoxybenzenetellurolate with dichloromethane gave products of indefinite composition. However, the reactions of lithium 2-benzothiophenetellurolate with dichloromethane and lithium benzenetellurolate with diiodomethane yielded his[aryltelluro]methane, and those of lithium ethynetellurolates with equimolar amounts of chloroiodomethane gave chloromethyl ethynyl tellurium compounds. v/c-Dibromides and sodium 4-ethoxybenzenetellurolate reacted to produce ethenes and bis[4-ethoxyphenyl] ditellurium.  

De Silva, Z. Monsef-Mirzai, W.R. MeWhinnie, J. Chem. Soc., Dalton Trtms. 1983, 2143. 

N-methyl amino acids are obtained by reaction of the N-tosyl derivative of the amino acid with methyl iodide, followed by removal of the tosyl substituent with HBr  

The N-methyl compound can also be formed by The aryl sulfonyl derivatives are very stable methylating with HCHO/HCOOH the benzyli-against acidic hydrolysis. Therefore, they are dene derivative of the amino acid, formed ini-suitable for the determination of free N-terminal tially by reaction of the amino acid with ben-amino groups or free 8-amino groups of pep- zaldehyde. The benzyl group is then eliminated 

Dimethyl amino acids are obtained by reaction with formaldehyde, followed by reduction with sodium borohydride  

Glycine Betaine Sugar beet, other samples of animal and plant origin 

Proline Stachydrine Stachys, orange leaves, lemon peel, alfalfa, Aspergillus oryzae 

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Nb-alkyls and aryls, e.g. MeNbCL and NbMe, Me2pCH2CH2pMe2) are known although relatively unstable. Cyclopenta-dienyl derivatives (h — C5Hs)2NbX3, (h -CjH5)Nb(CO)4 are relatively stable as is [Nb(CO)6] (NbClj + Na in diglyme + CO (pressure)). Tantalum compounds are very similar. 

It is a colourless gas which decomposes on heating above 420 K to give metallic tin, often deposited as a mirror, and hydrogen. It is a reducing agent and will reduce silver ions to silver and mercury(II) ions to mercury. SnSn bonding is unknown in hydrides but does exist in alkyl and aryl compounds, for example (CH3)3Sn-Sn(CH3)3. 

Very small quantities of bismuthine are obtained when a bismuth-magnesium alloy, BijMgj, is dissolved in hydrochloric acid. As would be expected, it is extremely unstable, decomposing at room temperature to bismuth and hydrogen. Alkyl and aryl derivatives, for example trimethylbismuthine, Bi(CHj)3, are more stable. 

Alkyl and aryl iodides usually react with magnesium more rapidly than the corresponding bromides, and the bromides very much more rapidly than the chlorides. Aryl (as distinct from alkyl) chlorides have usually only a slow reaction with magnesium and are therefore very rarely used. With alkyl and aryl iodides in particular, however, a side reaction often occurs with the formation of a hydrocarbon and magnesium iodide ... 

Alkyl and aryl-alkyl halides form 2-naphthyl ethers with 2-naphthol. 

The products from a mixture of alkyl and aryl halides may be represented by the following scheme ... 

Alkyl and aryl selenazoles are weakly basic, and their quaternary salts are easily hydrolvzed in aqueous solution. 

In this chapter we examine in turn the properties of alkyl and aryl-thiazoles that do not possess functional groups bonded directly to the thiazole ring. The general trends are underlined, and the applications of certains thiazole compounds in such areas as polymers, flavorings, and pharmacological and agricultural chemicals are discussed. 

Both alkyl and aryl nitriles are accessible by dehydration of amides... 

Quantum (Section 13 1) The energy associated with a photon Quaternary ammonium salt (Section 22 1) Salt of the type R4N X The positively charged ion contains a nitrogen with a total of four organic substituents (any combination of alkyl and aryl groups)... 

Na2S04 Ketones, acids, alkyl and aryl halides 12 1.25 150... 

Reaction with Carbon Nucleophiles. Unactivated a2iddines react with the lithium salts of malonates or p-keto esters in the presence of lithium salts to yield 3-substituted pyttohdinones (56—59), where R = alkyl and aryl, and R = alkoxyl, alkyl, and aryl. 

REPLACEThus alkyl- and aryl-substituted polyphosphazenes and their immediate precursors are also quite amenable to synthetic modifications, with the potential for the synthesis of a wide variety of materials being quite evident. 

Both alkyl and aryl isocyanates are found to trimerize upon heating or ia the preseace of catalysts to 1,3,5-trisubstituted hexahydro-j -triaziaetrioaes (18) (isocyanurates) (57). Only highly substituted isocyanates, such as tert-huty isocyanate [7188-38-7] and tert-octy isocyanate, fail to trimerize under these conditions. 

Uses. The largest use of lithium metal is in the production of organometaUic alkyl and aryl lithium compounds by reactions of lithium dispersions with the corresponding organohaHdes. Lithium metal is also used in organic syntheses for preparations of alkoxides and organosilanes, as weU as for reductions. Other uses for the metal include fabricated lithium battery components and manufacture of lithium alloys. It is also used for production of lithium hydride and lithium nitride. 

Acyl peroxides of structure (20) are known as diacyl peroxides. In this structure and are the same or different and can be alkyl, aryl, heterocychc, imino, amino, or fiuoro. Acyl peroxides of stmctures (21), (22), (23), and (24) are known as dialkyl peroxydicarbonates, 00-acyl O-alkyl monoperoxycarbonates, acyl organosulfonyl peroxides, and di(organosulfonyl) peroxides, respectively. and R2 ia these stmctures are the same or different and generally are alkyl and aryl (4—6,44,166,187,188). Many diacyl peroxides (20) and dialkyl peroxydicarbonates (21) ate produced commercially and used ia large volumes. 

Phosgene reacts with a multitude of nitrogen, oxygen, sulfur, and carbon centers. Reaction with primary alkyl and aryl amines yield carbamoyl chlorides which are readily dehydrohalogenated to isocyanates. Secondary amines also form carbamoyl chlorides. 

Uses. Phosphoms oxychloride is used extensively to manufacture alkyl and aryl orthophosphate triesters. A slight excess of the respective alcohol or phenol reacts with POCl at elevated temperatures and, if necessary, in the presence of a catalyst. 

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