Chloromethylation aromatic

Another group of polycondensations which allows for comparison of one-phasic and biphasic systems are polycondensation of bisphenols or bisthiophenols with a,(o-dibromoalkanes or bis(chloromethyl)aromatics. However, syntheses of polyamides from primary diamines are not suited for such studies, because association and precipitation of polyamide chains (via H-bonds) interferes with chain growth and cyclization. 

The reaction giving A is chloromethylation, a reliable metliod of adding a CH2OH equivalent to an aromatic ring. You may have been surprised at the use of reagent B to make an acid chloride. B is oxalyl chloride and is often used when pure acid chlorides are wanted - the other products are gases (which ). 

Chloromethylation of the aromatic nucleus occurs readily with alkyl and alkoxy substituents accelerating the reaction and halo, chloromethyl, carboxyl, and nitro groups retarding it. 

Chloromethjlation Reactions. The introduction of the chloromethyl group to both aHphatic and aromatic compounds is carried out by reaction of paraformaldehyde [30525-89-4] and hydrogen chloride. This method is used for synthesizing methyl chloromethyl ether [107-30-2], benzyl chloride [100-44-7], and chloromethyl acetate. 

Weak Base Anion Exchangers. Both styreoic and acryHc copolymers can be converted to weak base anion-exchange resias, but differeat syathetic routes are aecessary. Styreae—DVB copolymers are chloromethylated and aminated ia a two-step process. Chloromethyl groups are attached to the aromatic rings (5) by reactioa of chloromethyl methyl ether [107-30-2] CH2OCH2CI, with the copolymer ia the preseace of a Friedel-Crafts catalyst such as aluminum chloride [7446-70-0], AlCl, iroa(III) chloride [7705-08-0], FeCl, or ziac chloride [7646-85-7], ZaCl. ... 

The epoxidation is generally conducted in two steps (/) the polyol is added to epichlorohydrin in the presence of a Lewis acid catalyst (stannic chloride, boron triduoride) to produce the chlorohydrin intermediate, and (2) the intermediate is dehydrohalogenated with sodium hydroxide to yield the aliphatic glycidyl ether. A prominent side-reaction is the conversion of aliphatic hydroxyl groups (formed by the initial reaction) into chloromethyl groups by epichlorohydrin. The aliphatic glycidyl ether resins are used as flexibilizers for aromatic resins and as reactive diluents to reduce viscosities in resin systems. 

According to Section 4.02.3.1.8 substituents removed from the pyrazole ring by two or more saturated carbon atoms and substituents on the benzene ring of indazoles are similar in reactivity to the corresponding aromatic derivatives. For instance, chloromethyl-pyrazoles are comparable to benzyl chlorides and 5-hydroxyindazoles to /3-naphthols in their reactivity. 

BLANC QUELLET Chtoroalkylation Lewis acid catalyzed aromatic chloromethylation (Blanc) chloroalkylation (Quellet)... 

Carcinogens Cancer-producing agents Skin Respiratory Bladder/urinary tract Liver Nasal Bone marrow Coal tar pitch dust crude anthracene dust mineral oil mist arsenic. Asbestos polycyclic aromatic hydrocarbons nickel ore arsenic bis-(chloromethyl) ether mustard gas. p-naphthylamine benzidine 4-am i nodi pheny lam ine. Vinyl chloride monomer. Mustard gas nickel ore. Benzene. 

The six-position may be functionalized by electrophilic aromatic substitution. Either bromination (Br2/CH2Cl2/-5°) acetylation (acetyl chloride, aluminum chloride, nitrobenzene) " or chloromethylation (chloromethyl methyl ether, stannic chloride, -60°) " affords the 6,6 -disubstituted product. It should also be noted that treatment of the acetyl derivative with KOBr in THF affords the carboxylic acid in 84% yield. The brominated crown may then be metallated (n-BuLi) and treated with an electrophile to form a chain-extender. To this end, Cram has utilized both ethylene oxide " and dichlorodimethyl-silane in the conversion of bis-binaphthyl crowns into polymer-bound resolving agents. The acetylation/oxidation sequence is illustrated in Eq. (3.54). 

The introduction of a chloromethyl group on aromatic compounds (e.g. benzene 1) by reaction with formaldehyde 2 and gaseous hydrogen chloride in the presence of a catalyst is called the Blanc reaction ... 

In a first reaction step the formaldehyde 2 is protonated, which increases its reactivity for the subsequent electrophilic aromatic substitution at the benzene ring. The cationic species 4 thus formed loses a proton to give the aromatic hydroxymethyl derivative 5, which further reacts with hydrogen chloride to yield the chloromethylated product 3 ... 

Electron-rich aromatic substrates can react without a catalyst present. Modern variants of the Blanc reaction use chloromethyl ether" (e.g. (C1CH2)20, ClCH20Me) or methoxyacetyl chloride, since those reagents are more reactive and give higher yields. 

The chloromethylation can be generally employed in aromatic chemistry benzene, naphthaline, anthracene, phenanthrene, biphenyls and many derivatives thereof are appropriate substrates. The benzylic chlorides thus obtained can be further transformed, for example to aromatic aldehydes. Ketones like benzophe-none are not reactive enough. In contrast phenols are so reactive that polymeric products are obtained. ... 

An important side reaction is the formation of diaryl methane derivatives ArCHaAr. Moreover poly substituted products may be obtained as minor products. Aromatic compounds have been treated with formaldehyde and hydrogen bromide or hydrogen iodide instead of hydrogen chloride. The formaldehyde may be replaced by another aldehyde the term Blanc reaction however stands for the chloromethylation only. 

In an initial step the reactive formylating agent is formed from N,N-dimethylformamide (DMF) 2 and phosphorus oxychloride. Other N,N-disubstituted formamides have also found application for example A -methyl-A -phenylformamide is often used. The formylating agent is likely to be a chloromethyl iminium salt 4—also called the Vilsmeier complex (however its actual structure is not rigorously known)—that acts as the electrophile in an electrophilic substitution reaction with the aromatic substrate 1 (see also Friedel-Crafts acylation reaction) ... 

Inclusion of additional alkyl groups on the aromatic ring leads to decongestants with longer duration of action. Thus, reaction of the arylacetonitrile, 109, obtainable from hydrocarbon, 107, by chloromethylation (108), followed by displacement of the halogen by means of cyanide ion with ethylenediamine, leads to xylometazoline (111). The analogous reaction of the oxygenated derivative, 110, affords oxymetazoline (112). ... 

Finally, a series of 2-chloromethyl-5-aryl-1,3,4-oxadiazoles 82 were prepared by reaction of aromatic hydrazides 81 and a chloromethylorthofor-mate used as the solvent under microwave activation [62]. Potentially, the chloromethyl group could imdergo nucleophiUc substitution expanding the scope of this reaction (Scheme 28). 

Among the Friedel-Crafts alkylations of aromatic compounds with (chlorinated alkyl)silanes, the alkylation of benzene with (tt>-chloroalkyl)silanes in the presence of aluminum chloride catalyst was generally affected by two factors the spacer length between the Cl and silicon and the electronic nature of substituents on the silicon atom of (w-chloroalkyl)silanes. As the spacer length between the C—Cl and silicon increases from (chloromethyl)silane to (/i-chloroethyl)silane to (/-chloropropyl)silane, the reactivity of the silanes increases. As the number of chloro-groups on the silicon decreases from (chloromethyl)trichlorosilanes to (chloromethyl)methyldichlorosilanes to (chloromethyl)trimethylsilanes, the... 

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