P-Methylbenzyl bromide

Benzyl bromide reacts with ethoxide ion in dry alcohol to yield benzyl ethyl ether (C6H5CH2OC2HS) the rate depends upon both [RBr] and (OC2H5-]. Under the same conditions p-methylbenzyl bromide reacts l.S tinr as fast. 

One example of a mono-O-alkylation has been described so far. The reaction of H with p-methylbenzyl bromide in a 1 1 molar ratio resulted in the chiral resorcarene monoether 77a, which was exhaustively acylated to give resorcarene 77b containing one alkoxy and seven acetoxy groups . Recently, the chiral resorcarene 77d was obtained in the form of the pure enantiomers by monoacylation of H with camphorsulphonyl chloride, separation of the crude mixture by HPLC (11% for each diastereomer 77c), exhaustive O-methylation of the remaining hydroxy groups and alkahne hydrolysis. ... 

Living monofunctional poly THF Is prepared using p-methylbenzyl bromide ( ) as the co-lnitlator, and living dlfunctlonal poly THF Is prepared using m-xylylydlbromlde as colnltlator ( ). These procedures or adaptations thereof have been employed In the techniques described below. 

Significant differences in reactivity were observed between p-methylbenzyl bromide and benzyl bromide in the formation of carbenium ions by reaction with silver hexafluorophosphate. The former compound in conjunction with AgPFj was found to be a highly efficient initiator for the cationic polymerization of tetrahydrofuran (THF) at —10 °C. In situ formation of the benzyl ion was much slower, rendering syntheses of monodisperse poly(THF) impossible. 

Formation and Reaction of the Trimethylsilyl Ester of Squaric Acid. The most common method employed in the synthesis of squarate esters uses expensive silver nitrate and goes through the explosive disilver salt of squaric acid. It was conceived that sUyl esters of squaric acid 38 may be considered as silyl enol ethers that can undergo Si-O cleavage in the presence of a suitable fluoride source and that O-alkylation may be affected using electrophilic halides. Upon preparation of thebis(trimethyl-silyl) squarate 39 using BSA and reaction in situ with p-methylbenzyl bromide in the presence of a fluoride source, the desired benzyl squarate 40 was obtained in about 50% overall yield (eq 42). ... 

CIDNP has also been reported in reactions of organomercurials. Emission is observed from the couphng product of p-methylbenzyl-mercuric bromide and triphenylmethyl bromide (Beletskaya et al., 1971), while thermolysis of organomercury derivatives of tin such as t-C4H9HgSn(CH3)3 gave mixtures of isobutene and isobutane (by disproportionation of uncorrelated pairs of t-butyl radicals) showing A/E polarization (Mitchell, 1972). 

In the preparation of iodides, but not bromides, PMHS may be substituted for the TMDO. Chlorides can be obtained if thionyl chloride and zinc iodide are added to suppress the formation of symmetrical ethers.314 An example of this type of reductive chlorination is shown by the TMDO-mediated conversion of p-tolualdehyde into p-methylbenzyl chloride (Eq. 201).313 To obtain chlorides from aldehydes having electron-withdrawing groups such as nitro or carbomethoxy, the initial reaction is first carried out at —70° and the mixture is then heated to reflux in order to reduce the formation of symmetrical ether by-products. Zinc chloride is substituted for zinc iodide for the synthesis of chlorides of substrates with electron-donating groups such as methoxy and hydroxy.314... 

Although an appreciable amount of p-tolualdehyde was formed in oxidations with and without bromide, relatively little p-methylbenzyl alcohol and acetate resulted in the absence of bromide (1/10 to 1/25 as much as with bromide ion). The contrasting results suggest that the benzyl alcohol is a minor product in the autoxidation chain, as previously postulated by Boland, Bateman, and others (4, 7, 8, 15, 27), and is formed in the presence of bromide by solvolysis ... 

Industrially, terephthalic acid is produced by the cobalt(III) acetate, manganese(III) acetate, or ammonium molybdate-catalyzed air oxidation of />-xylene in acetic acid. Sodium bromide reduces the induction period and increases the rate of conversion to terephthalic acid. p-Xylene is initially oxidized to p-methylbenzyl hydroperoxide, and further oxidation gives p-methylbenzaldehyde and p-methylbenzoic acid ... 

This asymmetric phase-transfer method has been applied to enantio-selective Robinson annelation as shown in Scheme 14 (41). First, alkylation of a 1-indanone derivative with the Wichtetie reagent as a methyl vinyl ketone equivalent in the presence of p-CF3BCNB gives the S-alkylation product in 92% ee and 99% yield. With 1 -(p-trifluoro-methylbenzyl)cinchonidinium bromide, a pseudo-enantiomeric diaste-reomer of p-CF3BCNB, as catalyst, the -alkylation product is obtained in 78% ee and 99% yield. These products are readily convertible to the... 

Lithium diisopropylamide, 163 Sodium hydroxide-N-(p-Trifluoro-methylbenzyl)cinchoninium bromide, 325... 

Potassium r-butoxide-Hexamethyl-phosphoric triamide, 252 Potassium r-butoxide-Xonotlite, 254 Potassium hydroxide, 258 Potassium hydroxide-18-Crown-6, 258 Potassium hydroxide-Tricaprylyl-methylammonium chloride, 258 Sodium hydroxide-Methyltrioctyl-ammonium chloride, 192 Sodium hydroxide-Triethyl(2-methyl-butyl)ammonium bromide, 239 Sodium hydroxide-N-(p-Trifluoro-methylbenzyl)cinchoninium bromide, 325... 

Ethylbenzyl chloride Ethylene dibromide V,V -Dinitroethylenediamine Hexaethyl tetraphosphate M ethylbenzyl alcohol m-Benzenedisulfonic acid Methylbenzyl chloride V-Bromosuccinimide Octamethyl pyrophosphoramide p-Aminosalicylic acid Pentaerythritol tetranitrate Tris-(/3-chloroethyl) amine Tetraethylammonium bromide Tetraethyl pyrophosphate 2,2,6,6-Tetramethylolcyclohexanol... 

---