Aromatic Polysulfide Ethers

The technique of phase-transfer catalysis has been extensively apphed to the two-phase polycondensation using various phase-transfer catalysts, such as quaternary ammonium and phosphonium salts, crown ethers and poly(ethylene glycol)s. 5 - 53,75,87,n9,i5i Various types of condensation polymers such as aromatic polysulfonates and polysulfides, aromatic polyethers, ahphatic and aromatic polysulfides, and carbon-carbon chain polymers of high molecular weights hy the phase-transfer catalyzed polycondensation fi-om combinations of aromatic disulfonyl chlorides, phosphonic dichlorides, activated aromatic dichlorides, and aliphatic dihahdes, with bisphenol, aliphatic and aromatic dithiols, and active ethylene compounds. The two-phase polycondensation was generally carried out in a water-immiscible organic solvent-aqueous alkaline solution system at room temperature. The method of polycondensation offers a highly versatile and convenient synthetic method for a variety of condensation polymers. 

Recently, the above mentioned model reaction has been extended to polycondensation reactions for synthesis of polyethers and polysulfides [7,81]. In recent reports crown ether catalysts have mostly been used in the reaction of a bifunctional nucleophile with a bifunctional electrophile, as well as in the monomer species carrying both types of functional groups [7]. Table 5 describes the syntheses of aromatic polyethers by the nucleophilic displacement polymerization using PTC. 

Many compounds have been tested as ignition quality improvers—additives which shorten the ignition delay to a desirable duration. An extensive review in 1944 (6, 43) listed 303 references, 92 dealing with alkyl nitrates and nitrites 61 with aldehydes, ketones, esters, and ethers 49 with peroxides 42 with aromatic nitro compounds 29, with metal derivatives 28 with oxidation and oxidation products 22 with polysulfides 16 with aromatic hydrocarbons nine with nitration and four with oximes and nitroso compounds. In 1950, tests at the U. S. Naval Engineering Experiment Station (48) showed that a concentration of 1.5% of certain peroxides, alkyl nitrates, nitroaikanes, and nitrocarbamates increased cetane number 20 or more units. 

Recent efforts in the synthesis of sulfonated aromatic polymers are directed to the polymerization of sulfonated monomers (such as (b), (d), (g), (j), (k), and (1) shown in Scheme 3) [14,15,53,54,96-102] or coupling reactions of sulfonated compoimds with fimctional groups attached to a polymer backbone [ 103,104]. In post-sulfonation, attachment of the sulfonic acid group is restricted to the activated position ortho to the aromatic ether bond, as indicated in Scheme 4a, while in direct polymerization of sulfonated monomers, the sulfonic acid groups are attached to the deactivated site on the ring (Scheme 4b). An enhancement of stabUity toward desulfonation and a modestly higher acidity are expected for the structure shown in Scheme 4b. Recently, polymerization of sulfonated monomers was also used to obtain sulfonated polysulfone (m) via oxidation of a sulfonated polysulfide-polysulfone copolymer [105]. 

Preliminary investigations of the thermal pol5unerization reactions of newly obtained cyclic aromatic disulfides with p-diiodobenzene [624-38-4] and dibro-mobenzene [26249-12-7], orbis(4-bromophenyl) ether (4,4 -dibromodiphenylether, bis-p-bromophenyl ether, p,p -dibromodiphenyl ether) [2050-47-7] as a new alternative approach to PPS and other polysulfides have been reported (9). The reactions were carried out in diphenyl ether solution at 270°C giving polymers with 96% yield. 

In addition to various types of polysulfides reported previously, a new polysulfide has been synthesized using bischloroacetyl aromatic compounds, which are known to be highly reactive dichlorides. The two-phase polycondensation of bis(4-chloroacetylphenyl) ether XXII with 4,4 -oxybisbenzenethiol XI leading to polysulfide XXm was conducted at 30°C in a 1,2-dichloroethane-aqueous potassium hydroxide system [Eq.(10)]. ... 

T Polysulfide Organic polysulfide polymer Ozone, oils, solvents, thinners, ketones, esters, aromatic hydrocarbons Mercaptons, chlorinated hydrocarbons, nitro hydrocarbons, ethers, amines, hetercocyclics... 

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