Photolyses of a series of octaalkylcyclotetrasilanes (1) in a hydrocarbon solvent successively afforded hexaalkylcyclotrisilanes (2) and tetraalkyldisilenes (3). Compounds 2 and 3 were found to exhibit their absorption bands corresponding to the lowest energy transitions at λmax 300–330 and 390–440 nm, respectively.

Irradiation (>390 nm) of cyclopolysilanes, (RlRZSi), ( n = 3 or 4), in a mixed solvent (EtOH-MeCN-cyclo-C6HI2), with 9,lO-dicyanoanthracene as sensitiser, gave the corresponding a-ethoxy-co-hydropolysilanes resulting from ring-opening addition of ethanol to the polysilanes; a mechanism involving facile electron transfer from the polysilanes is proposed.

We investigated the hydroxyl and saponification values of 27 samples of Polysorbate 60 products that were commercially available worldwide. We observed that the values of most of the studied samples were not within the range established at the Joint FAO/WHO Expert Committee on Food Additives (JECFA), while they did agree with the specifications described in the USA, the EU and Japan. We believe that purities of the new commercial Polysorbate 60 samples are higher than those of the older products which were available when the JECFA specifications were discussed (around 1973). The present study suggests that the hydroxyl and saponification values of the current JECFA specifications for Polysorbate 60 should be re-evaluated.

The cyclopolysilanes (I) are photolytically cleaved in the presence of ethanol (II), forming the ethoxyhydropolysilanes (III).