Whiter than white

Pure water crystallized to snow appears white, for the transparence of the separate parts makes no tansparent whole. Various crystallized salts, when deprived to a certain extent of moisture, appear as a white powder. The accidentally opaque state of a pure transparent substance might be called white thus pounded glass appears as a white powder. The cessation of a combining power, and the exhibition of the atomic quality of the substance might at the same time be taken into the account. 

Quartz lamp, metal or plastic dishes which do not fluorescence, darkroom, protective gloves, safety glasses. 

Samples of textiles and paper, various washing powders. 

The textile and paper samples are placed in the dishes with the various washing powders and checked for blue fluorescence in a darkroom using the quartz lamp. If the washing powder contains whiteners the surface of the samples which have come in contact with the powder shine abright white. 

The whitener which is added to the washing powder converts the UV light into visible light, so that the treated surface appears whiter. This additional light radiation, which is light blue in color, can be realised with the help of many organic molecules with delocalised Jt-systems (for an example see below). 

---

The optical brightener Palanil 50—it makes your clothes look whiter than white and your T-shirts fluoresce in UV light—can be disconnected by the Wittig strategy to two molecules of the phosphonium ylid 51 and one of the dialdehyde 52. The availability of the dialdehyde, used in the manufacture of terylene, makes this route preferable to the alternative. 

Aryl-substituted oxazoles are strongly fluorescent. In solution they are suitable as luminous substances for liquid scintillation counters and optical brighteners. 4,4 -Bisoxazol-2-ylstilbene is added to washing agents. During the washing process, it is absorbed by the fibers so that the clothes appear to be whiter than white as a result of its blue fluorescence. 

Whiteners involve similar ingredients to those so well accepted in washing powders to give a whiter than white appearance. Since this may relate to a degree of colourising, i.e. a very pale blue or violet, its presence can frequently be seen by viewing the inside of an apparently white opaque container. Whiteness may be achieved by the addition of a material such as ultramarine. 

The optical brighiener Palanil (16)— whiter than white washing powders contain these brighteners—is manufactured by the Wittig reaction. Disconnection is bound to give an aryl-substituted ylid but the availability of aldehyde (17) (the corresponding acid is used to make terylene) makes this route the better of the two. 

The optical brightener Palanil (16)— whiter than white washing powders... 

Reasons for use color appears more brilliant, masking yellow color, whiter-than-white... 

---