Rhone-Poulenc Chimie

Rhone-Poulenc Specialites Chimiques

Roger Cocco

Michel Letoffe

Georges Nielsen

Straight-chain diorganopolysiloxanes having alkoxy endgroups, well adapted for formulation into single-component polysiloxane compositions which are stable on storage in the absence of moisture, but which crosslink into elastomeric state in the presence of moisture, are prepared by reacting a dihydroxydiorganopolysiloxane with a polyalkoxysilane, and advantageously also with an alkanol, in the presence of a catalytically effective amount of sodium hydroxide or potassium hydroxide.

Preparation of end-alkoxylated diorganopolysiloxanes

Functionalized diorganopolysiloxanes containing alkoxy endgroups, well adapted for the formulation of single-component cold-vulcanizable elastomer compositions therefrom, are prepared by reacting an .alpha., .omega.-dihydroxydiorganopolysiloxane oil with a polyalkoxysilane in the presence of a catalytically effective amount of lithium hydroxide.

LiOH catalyzed preparation of alkoxylated diorganopolysiloxanes

Essentially pure salicylic acid crystals, typically containing less than 0.01% inorganic salt, less than 0.01% para-hydroxybenzoic and 4-hydroxyisophthalic acid and well adopted for foodstuff and pharmaceutical applications, are facilely recovered from an aqueous solution of sodium salicylate by (i) adding an organic solvent for salicylic acid to such aqueous solution, in an amount sufficient to dissolve the salicylic acid corresponding to said sodium salt thereof, (ii) next adding thereto an at least stoichiometric amount, relative to said sodium salicylate, of a strong inorganic acid, and (iii) separating therefrom an essentially organic phase which comprises said salicylic acid and an aqueous phase which comprises an inorganic sodium salt.

Separation/purification of salicyclic acid

Essentially pure para-hydroxybenzoic acid crystals, typically containing but trace amounts of inorganic potassium salts and salicylic or 4-hydroxyisophthalic acid, well adopted for foodgrade applications, are facilely recovered from an aqueous solution of dipotassium and/or monopotassium para-hydroxybenzoate by (i) adding an organic solvent for para-hydroxybenzoic acid to such aqueous solution, in an amount sufficient to dissolve the para-hydroxybenzoic acid corresponding to said potassium salts thereof, (ii) next adding thereto an at least stoichiometric amount, relative to said dipotassium and/or monopotassium salt of para-hydroxybenzoic acid, and (iii) separating therefrom an essentially organic phase which comprises said para-hydroxybenzoic acid and an aqueous phase which comprises an inorganic potassium salt.

Growing community of inventors

Saint Symphorien D'Ozon, France

Roger Cocco