Showing papers on "Alkylation published in 1983"

Catalysis by Montmorillonites

Abstract: A B S T R A C T : A preliminary set of'rules' for acid-catalysis by ion-exchanged montmorillonites has been derived from the reaction of alkenes, alcohols and alicyclic acids over such catalysts. It has been shown that: 1. Cr(llI) and Fe(III) are the most active interlayer cations. Although AI is also active, the exact procedures used for the ion-exchange and washing steps appear to be critical for giving catalysts of reproducible activity. 2. Below 100~ the reactions proceed provided they involve tertiary or allylic carbocation intermediates, whereas at 150-180~ reactions involving primary and secondary carbocations are possible. 3. Reactions of carbocations with unsaturated hydrocarbons take place overwhelmingly in the interlayer region of the clay, where the hydrocarbon double bond can be effectively polarized. Reactions of carbocations with polar, oxygenated, species can take place on the surface of the clay particles as well as in the interlayer space. 4. When the acid-catalysed reactions are performed in the liquid phase and involve tertiary carbocations, the most suitable solvents are those which provide miscibility; 1,4-dioxan is especially good. However, when more acid conditions are required for the formation of primary and secondary carbocations a non-polar solvent is more efficacious. Montmorillonites or acid-treated montmorillonites have been used as catalysts for numerous reactions over the last few decades, some on an industrial scale, e.g. the dimerization of unsaturated fatty acids to dicarboxylic acids (Weiss, 1981) and the alkylation of phenols (Lucatello & Smith, 1972), whereas others have been used for laboratory synthesis, e.g. the preparation of di-2,2'-alkyl ethers (Adams et al., 1978; 1979). Most of these processes make use of the acidic properties of the montmorillonite, which derive from the dissociation of interlayer water molecules coordinated to the exchangeable cations (Mortland, 1968; Mortland & Raman, 1968; Fripiat & CruzCumplido, 1974). Weiss (1981) has suggested that the hydrogen ion concentration in the interlayer regions of these clays may be ~ 10 mol dm -3. It has been shown that in some examples of catalysis by ion-exchanged mont

Nucleophilic aromatic substitutions of unactivated aryl halides by methyl selenide anions. Synthesis and selective dealkylations of aryl alkyl selenides

Abstract: Synthese de (methyl phenyl)-, (aryl methyl)-, seleniures, de dialkylseleno-1,4- et (alkylseleno-1 alkylthio-4)-benzenes

Catalyst for alkylation of aromatic hydrocarbons

Abstract: This specification discloses a process for the alkylation of aromatics utilizing ZSM-23 catalyst. A particularly preferred embodiment utilizes ZSM-23 made from a forming mixture containing amorphous precipitated silica, as a silica source, including trace amounts of alumina and sodium chloride.

N-Alkylation of Pyrrole, Indole, and Several Other Nitrogen Heterocycles Using Potassium Hydroxide as a Base in the Presence of Polyethylene Glycols or Their Dialkyl Ethers

Abstract: The alkylation of pyrrole and indole in aqueous potassium hydroxide-organic two-phase systems in the presence of polyethylene glycols (PEG) or their dialkyl ethers (PEG-ether) as phase transfer catalysts (PTC) gave substantial quantities of the C-alkylated and C,N-polyalkylated products as well as the N-alkylated products. This fact is similar to that obtained in the presence of quaternary ammonium salts as PTC. In powdered potassium hydroxide-organic two-phase systems, the yields of the N-alkylated products were generally high. Especially, when PEG-ether were employed as solvents, the N-alkylated products were obtained in excellent yields under mild conditions. Imidazole, benzimidazole, carbazole, 2-methylindole, and benzotriazole were similarly N-alkylated in high yields by this method.

The Ruthenium Catalyzed N-Alkylation of Amides with Alcohols

Abstract: Amides reacted with primary alcohols in the presence of a catalytic amount of RuCl2(PPh3)3 at 180 °C to give the corresponding N-monoalkyl amides in fairly good yields. Thus, benzamide reacted with 1-octanol to give N-octylbenzamide in 76% yield with excellent product selectivity. Little esterification of amides with alcohols occurred and selectivity to the N-alkylation was high. Most of the amides gave N-monoalkyl amides but no N,N-dialkyl amides. But formamide reacted with 1-butanol to give N,N-dibutylformamide, as well as N-butylformamide, in low yield. RuCl2(PPh3)3 was the most effective catalyst for this reaction and RuHCl(PPh3)3 also had some catalytic activity.