Aromatics from methyl chloride

Hydrocarbon formation from methyl chloride can be catalyzed by ZSM-5482 483 or bifunctional acid-base catalysts such as W03 on alumina.420,447 The reaction on ZSM-5 gives a product distribution (43.1% aliphatics and 57.1% aromatics at 369°C) that is very similar to that in the transformation of methanol, suggesting a similar reaction pathway in both reactions.483 W03 on A1203 gives 42.8% C2-C5 hydrocarbons at 327°C at 36% conversion.447 When using methyl bromide as the feed, conversions are comparable. However, in this case, HBr can be very readily air-oxidized to Br2 allowing a catalytic cycle to be operated. Since bromine is the oxidant, the reaction is economical. The one step oxidative condensation of methane to higher hydrocarbons was also achieved in the presence of chlorine or bromine over superacidic catalysts.357... 

Compounds containing two primary amino groups attached to a benzene ring can be prepared by the reduction of dinitro compounds and of nitroanilines, usually with tin or stannous chloride and hydrochloric acid or with iron and very dilute hydrochloric acid. / ara-diamines may also be obtained by the reduction of aromatic amino-azo compounds (e.g., p-aminodimethylanihne from methyl orange, see Section IV,78). p-Phenylenediamine may also be prepared from p-nitroacetanilide reduction with iron and acid yields p-amino-acetaniUde,.which may be hydrolysed to the diamine. 

Hydroxybenzaldehyde has an agreeable aromatic odor, but is not itself a fragrance. It is, however, a useful intermediate in the synthesis of fragrances. The methyl ether of -hydroxybenzaldehyde, ie, -anisaldehyde, is a commercially important fragrance. Anisaldehyde can be made in a simple one-step synthesis from hydroxybenzaldehyde and methyl chloride. Another important fragrance, 4-(p-hydroxyphenyl)butanone, commonly referred to as raspberry ketone, can be prepared from the reaction of -hydroxybenzaldehyde and acetone, followed by reduction (see Flavors and spices). 

From the reaction of imidazole 161 and aromatic acid halides (Scheme 63), imidoyl chlorides 162 are obtained, which eliminate methyl chloride to form imidazo[2,l-6]l,3,4]thiadiazoles 163 upon extended heating (88H1935). 

The chemical properties of the chlorobenzenes and chloroethylenes differ strikingly from those of saturated aliphatic chlorine compounds and of aromatic compounds with chlorine substituted in a side chain. For example, methyl chloride and benzyl chloride are hydrolyzed by boiling alkali, giving the corresponding alcohols, whereas chlorobenzene is not affected by this treatment. In general there is a pronounced diminution in reactivity of a chlorine atom adjacent to an aromatic nucleus or double bond. 

Trinitrobenzoyl Azide, (02N)3CeHa.C0iN3 mw 282.13, N 29.79% col cryst(from methyl acet), mp 92-6°(dec)(Ref 2) to 98°(dec)(Ref 3), expl at higher temps d 1.673 at 20°(Ref 2) sol in acet or aromatic hydrocarbons insol in aliphatic hydro-carbons(Ref 3) can be prepd by adding aq Na azide soln in methyl acet to a stirred soln of 2,4,6-trinitrobenzoyl chloride in methyl acet at -5 to 0° (higher temps must be avoided)(Ref 2). This compd decomposes at RT and especially rapidly in soln... 

Isotactic Polystyrene. The familiar steam molding of pre-expanded particles has so far not been applied successfully to isotactic polystyrene. However, the polymer has been foamed, according to three disclosed methods. For example, finely divided acetone-insoluble polymer, with a melting point in excess of 200°C., is blended with a liquid selected from methylene chloride, aromatic hydrocarbons, or halogenated aromatic hydrocarbons. This blend is then heated (84). A mixture of molten polymer and methyl chloride, propane, or butane is suddenly depressurized (8). Foam may also be generated in a continuous manner directly from a butyllithium-initiated polymerization conducted in the presence of a 4/1 blend of benzene and petroleum ether (15). 

Phenylazo-1,2,4-triazole were prepared from benzenediazonium chloride and 1,2,4-triazole <07SC1977>. 5-Aryltriazole acyclonucleosides 134 with various aromatic groups on the triazole ring were synthesized from precursor 133 via the Suzuki coupling reaction in aqueous solution and promoted by microwave irradiation <07TL2389>. 1-Methyl-1,2,4-triazole 135 participated in a palladium-catalyzed C-H arylation reaction with 3,5-dimethoxychlorobenzene 136 to give coupled product 137 <07OL1449>. 

Acylations. Catalyzed by graphite the Friedel-Crafts acylation as well as the transformation of ethers to esters by acyl halides in refluxing 1,2-dichloroethane are realized. Although aliphatic chlorides are inferior to aromatic halides this method is quite general as shown by the synthesis of benzoates (e.g., allyl benzoate from allyl benzyl ether and methyl benzoates from methyl f-butyl ether). 

This synthesis of sulfenyl chlorides can also be used in the aliphatic series although here the limitation applies that most alkylsulfur halides are too unstable to be isolated from solution. In general, and also in the aromatic series, sulfenyl chlorides are easier to prepare than the bromides, whilst the iodides are known only in a few cases and the fluorides not at all. As an example, Schneider,665 chlorinating methanethiol in anhydrous carbon tetrachloride at —15°, obtained dimethyl disulfide dichloride [chloro(methyl)(methylthio)-sulfonium chloride] which passed into methanesulfenyl chloride when allowed to warm slowly to room temperature ... 

Diphenylmethane, (C6H5)2CH2, is best prepared from benzyl chloride, C6H5CH2CI, and benzene by the Friedel and Crafts synthesis. It melts at 26° and boils at 262°. Homo-logues of this compound can be prepared from aldehydes and aromatic hydrocarbons by the action of sulphuric acid. Thus, aldehyde or acetal and benzene when shaken with sulphuric acid give diphenyl-methyl-methane (unsymmetrical diphenylethane) ... 

Double bonds of benzene and related aromatic compounds do not react with diazoalkanes in 1,3-cycloadditions. The corresponding benzo-annellated dihydro-pyrazoles such as (1 a,6a)-6,9,9-trimethyl-7,8-diazabicyclo[4.3.0]nona-2,5,7-triene (6.98, R = H) can be synthesized, however, from methyl cyclohexa-l,4-dienecarboxy-late (6.97, R = H), as shown by Klarner et al. (1990). The reduction of the ester group to a methyl group was carried out with di-isobutylaluminum hydride (DIBAL-H), esterification of the OH group with methanesulfonyl chloride and reduction with lithium triethyl borohydride. The second double bond was introduced by bromina-tion with Br2 on a polymeric carrier after Bongini et al. (1980). Cycloaddition with 2-diazopropane in ether at -- 5 °C and the following steps gave 6.98 in a yield of 58%. 

One important consideration in any catalytic oxidation process at conditions of interest herein is the possible formation of hazardous incomplete oxidation products. One simple example is the formation of CI2 observed in the catalytic oxidation of methyl chloride over a-CrjOj/AljOj. Products that are even more toxic are of course possible. For all alcohols, aromatics, alkanes, aldehydes, naphthenes, ketones, and esters, the products of complete oxidation would of course be CO, and H,0. Although many VOCs are from these chemical classes, other associated compounds may lead to other products ... 

It is believed that methyl aromatic ether is protonated from the thermally stable pyridine hydrochloride to form an oxonium ion, which undergoes nucleophilic substitution with chloride to evolve methyl chloride and yield phenol derivatives, as exemplified here by the reaction of anisole. 

PROBLEM 14.9 The synthesis of toluene by the aluminum chloride-catalyzed Friedel-Crafts alkylation of benzene with methyl chloride is badly complicated by the formation of di-, tri-, and polymethylated benzenes. It appears that the initial product of the reaction, toluene, is more reactive in the Friedel-Crafts reaction than is benzene. Analyze the mechanism of electrophilic aromatic substitution to see why toluene is more reactive than benzene. Hint. Look carefully at substitution in the position directly across the ring from the methyl group (the para position) for toluene, and look for differences from the reaction with benzene. 

Quaternary ammonium ion exchange resins were produced initially by chloromethylating crosslinked polystyrene beads with chloromethyl methyl ether, followed by quaternization with tertiary amines. We have circumvented exposure to the highly carcinogenic bis(chloromethyl) ether, a common contaminant of commercial chloromethyl methyl ether, by employing l,4-bis(chloromethoxy)butane or 1-chloromethoxy-4-chlorobutane and have produced chloromethylated poly(oxy-2,6-dimethyl-1,4-phenylene) and polysulfone. Alternatively, chloromethyl methyl ether can be generated from acetyl chloride and methylal, and the reaction mixture utilized directly in chloromethylation of activated aromatic repeat units. 

Highly nucleophilic aromatic compounds are capable of arylating acyl-pyridinium salts. The first example of this striking reaction was described by Koenigs and Ruppelt s ho observed the formation of 4-(/>-dimethyl-aminophenyl) pyridine from pyridine, benzoyl chloride and dimethyl-aniline in the presence of copper. Benzaldehyde is also formed s, 736 and the copper is not necessaryThe dihydropyridine (105) is probably an intermediate. Other examples of the reaction are known s, 493 but attempts to isolate the intermediates have failed , though that from dimethyl-m-toluidine may have been obtained. In contrast, the dihydropyridines (106) were isolated when indole was the nucleophile. Skatole reacted similarly, at the 2-position of the indole nucleus, giving the fully aromatic 3-methyl-2-(4 -pyridyl)indole. These reactions failed with 2- and 4-picoline . Similar reactions occur between acylpyridinium salts and pyrroles (p. 71). 

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