Showing papers on "Alkylation published in 1982"

Preparation of porous crystalline synthetic material comprised of silicon and titanium oxides

Abstract: This invention relates to a porous crystalline synthetic material constituted by silicon and titanium oxides, a method for synthesizing said material, and the use thereof as a catalyst Said material is given the name titanium silicalite or TS-1, and corresponds to the following formula: xTiOsub2(1-x)SiOsub2 where x lies between 00005 and 004, preferably between 001 and 0025 The material is prepared starting from a mixture constituted by a source of silicon oxide and a source of titanium oxide The reaction takes place in the aqueous phase at a temperature of 130° to 200° C, and the solid product obtained is calcined in air at 550° C The TS-1 can be used for alkylation of toluene with methanol, or benzene with ethylene or ethanol, disproportioning of toluene to produce paraxylol, for cracking, hydrocracking, isomerization of n-paraffins and naphthenes, reforming, isomerization of substituted polyalkyl aromatics, disproportioning of aromatics, conversion of dimethylether and/or methanol or other alcohols to hydrocarbons, polymerization of compounds containing olefine or acetylene bonds, conversion of aliphatic carbonyl compounds into at least partly aromatic hydrocarbons, separation of ethyl benzene from other C 8 aromatic hydrocarbons, hydrogenation and dehydrogenation of hydrocarbons, methanation, oxidation, dehydration of aliphatic compounds containing oxygen, and conversion of olefines into compounds of high octane number

Lewis Acid Induced α‐Alkylation of Carbonyl Compounds

Abstract: Carbonyl compounds undergo α-alkylation via the corresponding silyl enol ethers using SN1 active alkyl halides or acetates in the presence of Lewis acids. This methodology extends the scope of carbonyl chemistry considerably, since SN1 active alkylating agents are generally base sensitive and therefore unsuitable for reactions with enolate anions or nitrogen analogs. A prime example is the α-tert-alkylation of aldehydes, ketones and esters.

Molybdenum catalysts for allylic alkylation

Abstract: This paper reports on the stoichiometric and catalytic allylic substituion reactions involving molybdenum complexes and the sensitivity of regioselectivity toward the nature of the ligands on molybdenum. Results indicated that the allylic alkylation catalyzed by molybdenum forms a useful and frequently complementary alternative to the palladium-catalyzed reaction. For example, regioselectivity appears more sensitive to ligand variation in the case of Mo. Higher selectivity for attach at a primary vs. secondary carbon of a ..pi..-allyl fragment occurs with Mo. It also appears that more flexibility in stereocontrol may exist. On the other hand, these reactions require higher temperatures and longer times. More thorough evaluation of this Mo chemistry will be required to delineate its full potential.

Process for alkylating aromatic compounds

Abstract: Aromatics are alkylated with C 2+ alkyl groups using as alkylating agents mixtures of hydrogen/hydrogen precursors and carbon oxide, preferably syngas, over catalysts comprising a zeolite of Constraint Index not above 12 and a metal component selected from Fe, Co, Ru, Mn, Rh and Os. The alkylation products can be dealkylated to produce olefins and aromatics.

Fluoride Salts on Alumina as Reagents for Alkylation of Phenols and Alcohols

Abstract: The effectiveness of alkali metal fluorides impregnated on alumina as a reagent for promoting alkylation was optimized with respect to the metal cation, the amount of impregnation, and the reaction solvent. Potassium or caesium fluoride on alumina in acetonitrile or 1,2-dimethoxyethane was concluded to be the best reaction system for general use. O-Alkylation of substituted phenols, primary and secondary alcohols, and a glycol was carried out mostly in good yields under mild conditions with simple experimental procedures.

Alkylation of aromatic hydrocarbons

Abstract: A process for the alkylation of aromatic hydrocarbons with alkylating agents having from one to five, and preferably three to five, carbon atoms. The reactants are brought into contact, preferably in the liquid phase, in the presence of a crystalline zeolite catalyst characterized by a silica to alumina ratio of at least 12 and a constraint index within the approximate range of 1-12. The reaction is conducted at 100° C. to 300° C. and a pressure of from about 105 N/m2 to about 2×107 N/m2.

Trialkylsulfonium- and Trialkylselenoniumhydroxides for the Pyrolytic Alkylation of Acidic Compounds

Abstract: Trialkylsulfonium- and trialkylselenoniumhydroxides are pyrolytic alkylation reagents that derivatize acidic compounds quantitatively inside the injector of the gas chromatograph. Trimethyl-sulfoniumhydroxide and Triethylsulfoniumhydroxide, the analogues of selenium respectively are stable in cool methanol solution for at least 6 months. The reagents are easy to handle and the byproducts formed are very volatile. Therefore the application of ternary sulfonium- and selenoniumhydroxides is equivalent or even superior to the use of the well known quartary ammoniumhydroxides.

Doubly Deprotonated Methyl 3‐Mitropropanoate, an Acrylic Ester d2‐reagent

Abstract: Methyl 3-nitropropanoate can be doubly deprotonated with LDA, both in the α-nitro and in the α-carbonyl position (→ 1). It is shown that the necessary cosolvent HMPT can be replaced by the cyclic urea DMPU, with almost equal results. The new reagent 1 is alkylated and hydroxyalkylated by alkyl halides and aldehydes, respectively, at the 2-position exclusively (see 2, 4, 6, 7). A double alkylation to methyl α,α-dialkyl-β-nitropropanoate 5 is possible. Elimination of HNO2 with DBN or even better with DBU in THF furnishes methyl α-methylenealkanoates 9 and methyl β-hydroxy-α-methylenealkanoates 10.

Liquid-phase alkylation and transalkylation process

Abstract: A process for alkylating aromatic hydrocarbons with C2 to C4 olefins and for transalkylating alkyl or poly-alkylaromatic compounds with an aromatic hydrocarbon. A major portion of the aromatic hydrocarbon is recycled to the alkylation zone while the remainder thereof and poly-alkylaromatic hydrocarbons are subjected to transalkylation in a separate transalkylation zone. Mono-alkylaromatics produced in the alkylation zone are separated from the other reaction products prior to transalkylation.

Para-selective zeolite catalysts treated with halogen compounds

Abstract: A process is provided for modifying ZSM-5 type zeolite catalysts with gaseous nitrogen-based treating agents in order to enhance the para-selective properties of such catalysts for the conversion of aromatic materials to dialkyl-substituted benzene compounds. Nitrogen-based treating agents include nitrogen dioxide and ammonia. Catalyst compositions so treated can be used in alkylation, transalkylation or disproportionation processes to provide product mixtures having exceptionally high concentrations of the para-dialkylbenzene isomer.

Zum stereochemischen Verlauf der Biosynthese von 2-Oxo-pantolacton: Synthese von stereospezifisch indiziertem Pantolacton aus Äpfelsäure†

Abstract: (+)-Pantolactone1 (13) has been synthesized from (−)-(S)-dimethyl malate (7) in 40% yield in a short sequence involving double alkylation (7 10 11), selective hydrolysis (11 12) and subsequent reduction (12 13). Through variation of the alkylating agents and preparation of the two diastereomeric 3-ethyl-3-methyl malates 14 and 15 it was possible to show that the diastereoselectivity of the second alkylation step is brought about by preferential attack from the Re-face of the critical enolate (9, see also Scheme 1). This knowledge, in turn, has been exploited for the synthesis of a sample of pantolactone specifically enriched with 13C in its Si-methyl group. Analysis of the 13C-NMR. spectrum of this sample together with the results of biosynthetic experiments previously reported by Aberhart demonstrates that the biological hydroxymethylation of 2-oxoisovaleric acid (3) to 2-oxopantoic acid (4), an important step in the biosynthesis of pantothenic acid, takes place in a retention mode (of. Scheme 2).

Silyl Phosphites. XVIII. Versatile Utility of α-(Trimethylsilyloxy)alkylphosphonates as Key Intermediates for Transformation of Aldehydes into Several Carbonyl Derivatives

Abstract: Carbonyl addition compounds of diethyl trimethylsilyl phosphite (DTMSP) with aldehydes were converted, by treatment with lithium diisopropylamide (LDA) followed by the successive alkylation and alkaline hydrolysis, to carbonyl derivatives involving aldehydes, unsymmetrical ketones, β,γ-unsaturated ketones, and carboxylic acids. β-Substituted carboxylic esters and γ-substituted lactones were prepared by use of the carbonyl addition compounds of DTMSP with α,β-unsaturated aldehydes.

Heterogeneous isoparaffin/olefin alkylation

Abstract: An improved process for alkylation of isoparaffins with olefins to yield a product which includes a high proportion of highly branched alkylates for blending into gasolines. The improved process comprises contacting the isoparaffins and olefins with a composite catalyst comprising a large pore zeolite and a Lewis acid.

Keten silyl acetal chemistry; simple synthesis of methyl jasmonate and related compounds by utilising keten methyl dimethyl-t-butylsilyl acetal

Abstract: Conjugate addition of keten silyl acetals to α,β-unsaturated carbonyl compounds in acetonitrile gave a quantitative yield of the corresponding methyl (3-trialkylsiloxyalk-2-enyl)acetates; subsequent site-specific electrophilic substitution yielded the corresponding 2-substituted 3-(alkoxycarbonylmethyl)alkanones. These novel addition and sequential alkylation reactions could be applied to a simple synthesis of methyl jasmonate, methyl didehydrojasmonate, and methyl dihydrojasmonate.

Studies on Chitin. VI. Preparation and Properties of Alkyl-Chitin Fibers

Abstract: Alkali-chitin was prepared by a simple procedure which included a freezing process in a sodium hydroxide-sodium dodecylsulfate system. Its alkylations were achieved with various alkyl halides of different chain lengths and bulkiness. The affinity toward water or formic acid was remarkably enhanced by the alkylations in spite of the low degree of substitution. The increase in hydrophilicity was considered to be result from the partial destruction of crystalline structure in the chitin molecule. The alkyl-chitin fibers were successfully prepared by spinning the solution of alkyl-chitin in formic acid-dichloroacetic acid mixture into ethyl acetate. The extent of swelling with water was found to correspond both to the chain length and the bulkiness of the alkyl group. The hydroxyl group at the C6 position is considered to be substituted prior to that of C3 position, according to a 13C NMR study. 1H NMR and elemental analysis proved useful in estimting the degree of alkylation even in the case of low degree of substitution.

The Transition Metal-catalyzed N-Alkylation and N-Heterocyclization. A Reductive Transformation of Nitroarenes into (Dialkylamino)arenes and 2,3-Dialkyl-substituted Quinolines Using Aliphatic Aldehydes under Carbon Monoxide

Abstract: The catalytic N-alkylation and N-heterocyclization of nitroarenes occur at 180 °C under a carbon monoxide pressure of 70 atm and in the presence of aldehyde and such transitionmetal complexes as rh...

Synthesis of pseudo cofactor analogues as potential inhibitors of the folate enzymes.

Abstract: Reaction of 5,6,7,8-tetrahydrofolic acid (THF,7) with phosgene, thiophosgene, and cyanogen bromide gave the bridged derivatives, 5,10-(CO)-THF (8), 5,10-(CS)-THF (9), and 5,10-(C = NH)-THF (11), respectively. Catalytic hydrogenation of 10-(chloroacetyl)folic acid (2) gave 5,10-(CH2CO)-THF (12). A similar reaction with 10-(3-chloropropionyl)folic acid (3) gave 10-(ClCH2CH2CO)-THF (14) rather than 5,10-(CH2CH2CO)-THF (13). In the catalytic hydrogenation of 10-ethoxalylfolic acid (5), the initial product 10-(EtO2CCO)-THF (22) rearranged readily to give 5-(EtO2CCO)-THF (21). Acylation of THF with chloroacetyl chloride gave a N5,N10-diacylated product (18 or 19), which could not be converted to 5,10-COCH2)-THF (17). Reductive alkylation of THF with glyoxylic acid and 5-hydroxypentanal, respectively, gave 5-(HO2CCH2)-THF (24) and 5-[HO(CH2)5]-THF (25). Reductive dialkylation of THF with formaldehyde gave 5,10-(CH3)2-THF (27), whereas glyoxal gave 5,10-CH2CH2)-THF (10). Also, both folic acid and 5-(CHO)-THF were reductively alkylated with formaldehyde to give 10-methylfolic acid (6) and 5-(CHO)-10-(CH3)-THF (28), respectively. These compounds were tested as inhibitors of the enzymes involved in folate metabolism and for activity against lymphocytic leukemia P388 in mice.