Patent GB-717207-A (GB)
Title: Improvements in or relating to the preparation of alkali metal hyposulfite
IPC: C01B17/66
Filed: 1952-06-25
Abstract: The alkali metal addition product of an ether of a polyhydric alcohol is produced for example by commingling the alkali metal with the ether.  In the case of sodium, potassium and lithium this is best done in the solid form, preferably as a dispersion in an inert medium; the other metals may be used in molten form.  The reaction is best performed below the reflux temperature of the ether.  The product is greyish white and decomposes on exposure to the air. Suitable alcohols from which the ethers may be derived are n-alkanediols such as ethylene glycol, propylene glycol, butylene glycol, 1,3-propanediol and a -n-amylene glycol up to the higher molecular weight alcohols such as decalene glycol, n-decalene glycol and alcohols including ether linkages such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and tetrabutylene glycol, and triols such as glycerol.  The ethers are derived from these alcohols by replacing the hydrogen atoms of one or more of the hydroxyl groups with a hydrocarbon radical such as methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl, sec.-butyl, the isomeric amyl, hexyl, heptyl, cetyl, nonyl, higher alkyls up to and including those containing 18 carbon atoms, whether straight or branched chain, cyclobutyl, cyclopentyl, cyclohexyl, methylcyclohexyl, phenyl, o-tolyl, m-tolyl, p-tolyl, the xylyls, o-diphenyl and p-diphenyl, but alkyl groups are preferred, alkyl ethers of the glycols being most satisfactory. Ethers specified are ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, propylene glycol diethyl ether, ethylene glycol diisoamyl ether, glycerol diisoamyl ether, ethylene glycol monocyclohexyl ether, ethylene glycol dicyclobutyl ether, tetraethylene glycol dimethyl ether, triethylene glycol diethyl ether, glycerol a ,g -diphenyl ether, glycerol a -monophenyl ether, glycerol monoguaiacol ether, ethylene glycol diphenyl ether, tetraethylene glycol diphenyl ether, ethylene glycol mono-o-tolyl ether, ethylene glycol di-p-diphenyl ether, ethylene glycol methyl ethyl ether, ethylene glycol ethyl butyl ether, propylene glycol methyl ethyl ether, tetraethylene glycol methyl ethyl ether, diethylene glycol methyl ethyl ether, ethylene glycol phenyl ethyl ether, propylene glycol phenyl methyl ether, tetraethylene glycol phenyl ethyl ether, dipropylene glycol phenyl methyl ether, ethylene glycol phenyl o-tolyl ether, propylene glycol phenyl o-diphenyl ether and diethylene glycol phenyl p-tolyl ether.ALSO:Alkali metal hyposulphites are prepared by contacting an alkali metal addition product of an ether of a polyhydric alcohol with sulphur dioxide, or by introducing an alkali metal into a reaction medium consisting of an ether of a polyhydric alcohol and sulphur dioxide or by introducing alkali metal and sulphur dioxide into an ether of a polyhydric alcohol.  The hyposulphite is precipitated and removed, e.g. by filtration or centrifuging.  Gaseous sulphur dioxide, preferably at between -10 and +30 DEG C., or liquid sulphur dioxide at below -10 DEG C. or with increased pressure, may be used. In the Example, a 50 per cent. sodium dispersion in xylene is added to ethylene glycol dimethyl ether whilst sulphur dioxide is passed in at 10 DEG  C.  The alkali metal addition product is produced for example by commingling the alkali metal with the ether.  In the case of sodium, potassium and lithium this is best done in the solid form, preferably as a dispersion (see below) in an inert medium; the other metals may be used in molten form.  The reaction is best performed below the reflux temperature of the ether.  The product is greyish-white and decomposes on exposure to the air. Suitable alcohols from which the ethers may be derived are n-alkanediols such as ethylene glycol, propylene glycol, butylene glycol 1.3-propanediol and a -n-amylene glycol up to the higher molecular weight alcohols such as decalene glycol, n-decalene glycol and alcohols including ether linkages such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and tetrabutylene glycol, and triols such as glycerol.  The ethers are derived from these alcohols by replacing the hydrogen atoms of one or more of the hydroxyl groups with a hydrocarbon radical such as:- methyl, ethyl, propyl, iso-propyl,n-butyl iso-butyl, secbutyl the isomeric amyl, hexy, heptyl, cetyl, nonyl, higher alkyls up to and including those containing 18 carbon atoms, whether straight or branched chain, cyclobutyl, cyclopentyl, cyclohexyl, methylcyclohexyl, phenyl, o-tolyl, m-tolyl, p-tolyl, the xylyls, o-diphenyl and p-diphenyl, but alkyl groups are preferred, alkyl ethers of the glycols being most satisfactory.  Ethers specified are:-ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, ethylene glycol diethyl ether, propylene glycol diethyl ether, ethylene glycol diisoamyl ether, glycerol diisoamyl ether, ethylene glycol monocyclohezyl ether, ethylene glycol dicyclobutyl ether, tetraethylene glycol dimethyl ether, triethylene glycol diethyl ether, glycerol a , g -diphenyl ether, glycerol a -monophenyl ether, glycerol monoguaiacol ether, ethylene glycol diphenyl ether, tetraethylene glycol diphenyl ether, ethylene glycol mono-o-tolyl ether, ethylene glycol di-p-diphenyl ether, ethylene glycol methyl ethyl ether, ethylene glycol ethyl butyl ether, propylene glycol methyl ethyl ether, tetraethylene glycol methyl ethyl ether, diethylene glycol methyl ethyl ether, ethylene glycol phenyl ethyl ether, propylene glycol phenyl methyl ether, tetraethylene glycol phenyl ethyl ether, dipropylene glycol phenyl methyl ether, ethylene glycol phenyl o-tolyl ether, propylene glycol phenyl o-diphenyl ether and diethylene glycol phenyl p-tolyl ether.  The alkali metal dispersions, notably sodium, are prepared, e.g. by fusing the metal in an inert medium and sub-dividing to a particle size of less than 1, up to 50 microns.  Suitable media mentioned are hydracarbons viz xylene, toluene, benzene, gasoline, kerosene, n-nonane, n-decane, and heavy alkylate; a dispersing agent, e.g. a soap such as the sodium salt of a fatty acid, activated carbon, charcoal, carbon black, an organic hydroperoxide, or a mercaptide, may be added.