Olefin alkylation, synthesis

Scheme 21. Zr-catalyzed asymmetric olefin alkylation is used in conjunction with Pd-catalyzed addition of an arylox-ide to an epoxide and Mo-catalyzed olefin metatheses in Hoveyda s total synthesis of nebivolol (1998).

Chloroform stability, lipid hydroperoxides, 676 Chlorohydridosilane, alkyl sodium alkyl peroxide reaction, 783 Chlorohydrins, olefin oxidation synthesis, 792-3... 

The main purpose of the work reported here was to develop a low-cost, effective, and nonvolatile 2,4,6-trialkylphenol antioxidant. We discuss the synthesis of some new types of phenolic antioxidants, particularly those resulting from a-olefin alkylation of phenols. We also report the effectiveness of these stabilizers in polypropylene and speculate on the effect of structure on their effectiveness. 

This patent predates, both in filing and in issue, the big Zosel patent described first in this pendix. There are many anecdotal stories, perhaps some apocryphal, that have circulate about the aluminum alkyl work carried out at the Max Planck Institut fur Kohlenforschung in Mulheim (Ruhr), Germany. It was found during the aluminum alkyl synthesis studies that supercritical ethylene could separate aluminum trialkyls and olefins by carbon number. 

Borabicyclo[3.3.1]nonane (9-BBN) has found use in the selective hydro-boration of alkenes in the presence of other reducible functional groups and its reaction with alkynylstannates has been studied. o-Stannyl- and a-silyl-substituted crotyl-9-BBN show promise as reagents for the stereo-regulated synthesis of acyclic systems. A series of papers covers the question of olefin-alkyl exchange in. 5-alkyl-9-BBN s, " the kinetics of reduction of substituted benzaldehydes with 9-BBN, and the kinetics and mechanism of hydroboration of alkynes with 9-BBN dimers. Selective dehalogenation of tertiary alkyl, benzyl, and allyl halides in the presence of secondary or primary alkyl or aryl halides is possible with (165). The... 

Zeolite MCM-22 in its Br0nsted-acid form has been described in the hterature as a useful catalyst for a variety of acid-catalyzed reactions, such as iso-alkane/olefin alkylation [e.g.40,41],skeletal and double-bond isomerization of olefins [42] and ethylbenzene synthesis via alkylation of benzene with ethylene [43], to name merely a few. Moreover, due to its very large intracrystalline cavities, zeolite MCM-22 has also been demonstrated to be a suitable host material for a variety of catalytically active guests, e.g. transition metal complexes which are useful in selective oxidation [44] or hydrogenation [45] reactions. Due to these interesting properties it seems worthwhile to focus on the synthesis features of MCM-22 (see below). 

Shown in Table 1 [1] is a typical MTG hydrocarbon product analysis. The selectivity can of course be varied by changing reaction conditions, as shown later. The hydrocarbon distribution displays some noteworthy features little or no hydro n, methane, or ethane is produced the carbon number range is limited mainly to C ClO (it is fortuitous that ClO is also the normal end point of conventional gasoline) the fraction contains significant amounts of isobutane, which will be useful for alkylate synthesis under conditions in which light olefins are brought into balance with isobutane and the aromatics are nearly exclusively methyl substituted. 

Palladium-catalyzed synthesis of oxygen-containing heterocycles involving a C-H activation/C-C formation process has been substantially investigated in the past few decades. Palladium-catalyzed arylation, olefination, alkylation. 

Catalysts used in the polymerization of C-5 diolefins and olefins, and monovinyl aromatic monomers, foUow closely with the systems used in the synthesis of aHphatic resins. Typical catalyst systems are AlCl, AIBr., AlCl —HCl—o-xylene complexes and sludges obtained from the Friedel-Crafts alkylation of benzene. Boron trifluoride and its complexes, as weU as TiCl and SnCl, have been found to result in lower yields and higher oligomer content in C-5 and aromatic modified C-5 polymerizations. 

The synthesis of 2,4-dihydroxyacetophenone [89-84-9] (21) by acylation reactions of resorcinol has been extensively studied. The reaction is performed using acetic anhydride (104), acetyl chloride (105), or acetic acid (106). The esterification of resorcinol by acetic anhydride followed by the isomerization of the diacetate intermediate has also been described in the presence of zinc chloride (107). Alkylation of resorcinol can be carried out using ethers (108), olefins (109), or alcohols (110). The catalysts which are generally used include sulfuric acid, phosphoric and polyphosphoric acids, acidic resins, or aluminum and iron derivatives. 2-Chlororesorcinol [6201-65-1] (22) is obtained by a sulfonation—chloration—desulfonation technique (111). 1,2,4-Trihydroxybenzene [533-73-3] (23) is obtained by hydroxylation of resorcinol using hydrogen peroxide (112) or peracids (113). 

Synthesis. Dialkyl peroxides are prepared by the reaction of various substrates with hydrogen peroxide, hydroperoxides, or oxygen (69). They also have been obtained from reactions with other organic peroxides. For example, dialkyl peroxides have been prepared by the reaction of hydrogen peroxide and alkyl hydroperoxides with alMating agents, eg, RX and olefins (33,66,97) (eqs. 24—27). 

Organoaluminum Compounds. Apphcation of aluminum compounds in organic chemistry came of age in the 1950s when the direct synthesis of trialkylalurninum compounds, particularly triethylalurninum and triisobutylalurninum from metallic aluminum, hydrogen, and the olefins ethylene and isobutylene, made available economic organoalurninum raw materials for a wide variety of chemical reactions (see a-BONDED alkyls and aryls). 

A considerable amount of hydrobromic acid is consumed in the manufacture of inorganic bromides, as well as in the synthesis of alkyl bromides from alcohols. The acid can also be used to hydrobrominate olefins (qv). The addition can take place by an ionic mechanism, usually in a polar solvent, according to Markownikoff s rule to yield a secondary alkyl bromide. Under the influence of a free-radical catalyst, in aprotic, nonpolar solvents, dry hydrogen bromide reacts with an a-olefin to produce a primary alkyl bromide as the predominant product. Primary alkyl bromides are useful in synthesizing other compounds and are 40—60 times as reactive as the corresponding chlorides (6). 

Methyl ketones are important intermediates for the synthesis of methyl alkyl carbinols, annulation reagents, and cyclic compounds. A common synthetic method for the preparation of methyl ketones is the alkylation of acetone derivatives, but the method suffers limitations such as low yields and lack of regioselectivity. Preparation of methyl ketones from olefins and acetylenes using mercury compounds is a better method. For example, hydration of terminal acetylenes using HgSO gives methyl ketones cleanly. Oxymercuration of 1-olefins and subsequent oxidation with chromic oxide is... 

Contents Introduction and Principles. - The Reaction of Dichlorocarbene With Olefins. - Reactions of Dichlorocarbene With Non-Olefinic Substrates. -Dibromocarbene and Other Carbenes. - Synthesis of Ethers. - Synthesis of Esters. - Reactions of Cyanide Ion. - Reactions of Superoxide Ions. - Reactions of Other Nucleophiles. - Alkylation Reactions. - Oxidation Reactions. - Reduction Techniques. - Preparation and Reactions of Sulfur Containing Substrates. -Ylids. - Altered Reactivity. - Addendum Recent Developments in Phase Transfer Catalysis. 

Tlie interest in the preparation and use of dithiolium salts in connection with the synthesis of TTF derivatives led to the development of a new uses of heteroaromatic cations in organic synthesis. Based on that, a new carbonyl olefination for the synthesis of numerous heterofulvalenes was developed (77S861). For example, 2-dimethoxyphosphinyl-l,3-benzodithiole was deprotonated with butyllithium in THF at -78°C and the resulting phosphonate carbanion reacted with 9-alkyl-acridones to give the dithia-azafulvalenes of type 45 (78BCJ2674) (Scheme 15). 

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