Ytterbium(III) chloride
Colorless solid
- 279.40 g · mol -1 ( anhydrous)
- 387.49 g · mol -1 ( hexahydrate)
Fixed
2.57 g · cm -3
703 ° C
1900 ° C.
Soluble in water
Template: Infobox chemical / molecular formula search available
Ytterbium (III ) chloride is an inorganic chemical compound of ytterbium and is one of the chlorides.
Production and representation
Ytterbium is prepared by reaction of ytterbium ( III) oxide with either carbon tetrachloride or hot hydrochloric acid.
The anhydrous compound is prepared by heating the water-containing compound in the HCl stream at slowly increasing temperature. At 350 ° C, the substance is water-free.
Properties
Ytterbium (III ) chloride, aluminum chloride is crystallized in a cubic - layer structure. In the gas phase to form smaller units such as [ YbCl6 ] 3 - or Yb2Cl6.
Use
Catalyst in the organic chemistry
Ytterbium (III ) chloride acts on the basis of the single unpaired f - electrons as a Lewis acid. This allows the compound to form in transition states and complexes to catalyze alkylation reactions such as aldol reactions and the Pictet -Spengler reaction.
Wherein the aldol reaction is ytterbium (III ) chloride as an auxiliary catalyst in the palladium -catalyzed aldol reaction decarboxylating an enolate with an aldehyde. The transition states A and B show the coordination of the Ytterbiumsalzes. For the above aldol reaction decarboxylative with R = tert -butyl and R '= - (CH2) 2Ph, the comparison of the yields of various Lewis acids is a particularly high yield of ytterbium ( III) chloride.
Ytterbium (III ) chloride as a Lewis acid catalyzes the Pictet -Spengler reaction for the production of tetrahydro- beta- carbolines of which synthetic indole alkaloids are produced. This allows for high yields, and reduces the reaction time of day to 24 hours.
The small size of the Yb3 ions enables rapid catalysis, but the selectivity is small. For example, the mono- acetylation of meso -1 ,2- diols having two hours fastest with ytterbium (III ) chloride, chemoselectivity for the monoacetylated product ( on the other hand, 50 % low compared to cerium ( III) chloride 23 h of reaction time, 85%).
Ytterbium (III ) chloride is a strong catalyst for the acetal with trimethylorthoformate. Compared with cerium ( III) chloride, and erbium ( III) chloride, the Ytterbiumsalz is most effective. It achieves high yields in a fast reaction at ambient temperature in a variety of aldehydes.
NMR shift reagent
Ytterbium can be used as NMR shift reagent, such as in membrane biology for tracking the movements of 39K and 23Na , which play an important role in nerve signals.