Pyridinium chloride, occasionally used

An example of the first type is the emulsion stabiliser as exemplified by sodium oleyl sulphate, cetyl pyridinium chloride and poly(ethylene oxide) derivatives. For a number of applications it is desirable that the latex be thickened before use, in which case thickening agents such as water-soluble cellulose ethers or certain alginates or methacrylates may be employed. Antifoams such as silicone oils are occasionally required. 

Very occasionally, solvents other than benzene, such as toluene,23 CH2CI224 or DME,25 have been used. It must be mentioned that the use of polar solvents tends to promote the formation of methylthiomethyl ethers in oxidations with activated DM SO.26 So far, pyridinium trifluoroacetate27 is the acid most commonly used, while phosphoric28 and dichloroacetic acid18 are being used less often. Acids rarely used include pyridinium tosylate,29 pyridinium phosphate30 and pyridinium chloride,31 which are normally employed in the presence of excess of pyridine. 

Heptyl o-phenylene phosphite. Place 87.0 g (0.5 mol) of o-phenylene phosphorochloridite, 39.5 g (0.05 mol) of dry redistilled pyridine and 500 ml of dry ether, in a 2-litre conical flask and cool to 0 °C. Add 58.1 g (0.5 mol) of heptan-l-ol dissolved in 400 ml of dry ether during about 5 minutes with occasional shaking. Stopper the flask and allow the reaction to proceed at room temperature overnight. Filter off the precipitated pyridinium chloride under suction, wash well with dry ether and remove the ether from the combined filtrate and washings on a rotary evaporator to obtain 127.0 g (100%) of heptyl o-phenylene phosphite as a colourless oil of sufficient purity for use in the next stage. 

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