1. History

2. Chemical properties

3. Preparation

4. Uses
    Catalysis  Biology 

5. References

History

Ytterbium, a lanthanide series element, was discovered in 1878 by the Swiss chemist Jean-Charles Galissard de Marignac, who named the element after a town (Ytterby) in Sweden. The first synthesis of YbCl₃ in the literature was that of Jan Hoogschagen in 1946. YbCl₃ is now a commercially available source of Yb³⁺ ions and therefore of significant chemical interest.

Chemical properties

The valence electron configuration of Yb⁺³ (from YbCl₃) is 4f¹³5s²5p⁶, which has crucial implications for the chemical behaviour of Yb⁺³. Also, the size of Yb⁺³ governs its catalytic behaviour and biological applications. For example, while both Ce⁺³ and Yb⁺³ have a single unpaired f electron, Ce⁺³ is much larger than Yb⁺³ because lanthanides become much smaller with increasing effective nuclear charge as a consequence of the f electrons not being as well shielded as d electrons. This behavior is known as the lanthanide contraction. The small size of Yb⁺³ produces fast catalytic behavior and an atomic radius (0.99 Å) comparable to many biologically important ions.

The gas-phase thermodynamic properties of this chemical are difficult to determine because the chemical can disproportionate to form [YbCl₆]⁻³ or dimerize.^[9] The Yb₂Cl₆ species was detected by electron impact (EI) mass spectrometry as (Yb₂Cl₅⁺).^[9] Additional complications in obtaining experimental data arise from the myriad of low-lying f-d and f-f electronic transitions.^[11] Despite these issues, the thermodynamic properties of YbCl₃ have been obtained and the C_3V symmetry group has been assigned based upon the four active infrared vibrations.^[11]

Preparation

YbCl₃ is prepared from Yb₂O₃ with either high-temperature carbon tetrachloride gas,^[13] or hot hydrochloric acid followed by drying at high temperature.^[14]

2 Yb₂O₃ + 3 CCl_4(g) → 4 YbCl_3(s) + 3 CO_2(g)

Yb₂O₃ + 6 HCl_(g) → 2 YbCl_3(s) + 3 H₂O

In practice{{clarify|date=September 2013}} there are better ways to prepare YbCl₃ for lab use. The aqueous HCl/ammonium chloride route{{clarify|date=September 2013}} is unsophisticated{{clarify|date=September 2013}} but very effective. Alternatively hydrated YbCl₃ may be dehydrated using a variety of reagents, particularly trimethylsilyl chloride. Other methods have been published including reacting the finely powdered metal with mercuric chloride at high temperature in a sealed tube.{{citation needed|date=December 2016}} A variety of routes to solvated YbCl₃ have been reported{{citation needed|date=September 2013}} including reaction of the metal with various halocarbons in the present of a donor solvent such as THF, or dehydration of the hydrated chloride using trimethylsilyl or thionyl chloride, again in a solvent such as THF.

Uses

Catalysis

YbCl₃, with a single unpaired electron, acts as a Lewis acid in

order to fill the 4f orbital. The Lewis acidic nature of YbCl₃ allows YbCl₃ to coordinate (usually

as [YbCl₂]⁺) in transition states to catalyze alkylation reactions, such as the aldol reaction^[15] and the Pictet-Spengler reaction.^[16]

Aldol reaction

The aldol reaction is a versatile reaction in synthetic organic chemistry. YbCl₃ serves a Lewis acid catalyst which aids the Pd(0) catalyzed decarboxylative aldol reaction between a ketone enolate and an aldehyde. Transition states A and B show the coordination method of the ytterbium salt as a Lewis acid.^[15] For the depicted decarboxylative Aldol reaction with R = tert-butyl and R’ = -(CH₂)₂Ph, the reaction yields show YbCl₃ is an effective Lewis acid catalyst:

Pictet-Spengler reaction

The Pictet-Spengler reaction produces a valuable tetrahydro-β-carboline ring system which can be later used for synthetically prepared indole alkaloids.^[16] The Lewis acid catalyzed reaction with YbCl₃ gave excellent yields and reduced reaction times from four days to 24 hours.^[16]

Esterification

The small size of Yb³⁺ provides fast catalysis, but at the cost of selectivity. For example, the mono-acetylation ofmeso-1,2-diols is fastest (2 h) with YbCl₃, but chemoselectivity for the mono-acetylated product is low (50%) compared to CeCl₃ (23

h, 85%).^[21]

Acetalisation

Ytterbium(III) chloride is a powerful catalyst for the formation of acetals using trimethyl orthoformate.^[22] In comparison with cerium(III) chloride and erbium(III) chloride, the ytterbium salt was found to be the most effective. Excellent yields are obtained from a variety of aldehydes within a few minutes at room temperature, as in the example above involving an acid-sensitive aldehyde.

Biology

YbCl₃ is a NMR shift reagent that produces different resonances with nuclei in contact with the YbCl₃ versus those nuclei not in contact with the shift reagent.^[23] Generally paramagnetic species, such as a (lanthanide)⁺³ ion, are desirable shift reagents.^[23] Membrane biology has been greatly influenced by YbCl₃, where³⁹K⁺ and²³Na⁺ ion movement is critical in establishing electrochemical gradients.^[23] Nerve signaling is a fundamental aspect of life that may be probed with YbCl₃ using NMR

techniques. YbCl₃ may also be used as a calcium ion probe, in a fashion similar

to a sodium ion probe.^[26]

YbCl₃ is also used to track digestion in animals. Certain additives to swine feed, such as probiotics, may be added to either solid feed or drinking liquids. YbCl₃ travels

with the solid food and therefore helps determine which food phase is ideal to incorporate the food additive.^[27] The YbCl₃ concentration is quantified by inductively coupled plasma mass spectrometry to within 0.0009 μg/mL. YbCl₃ concentration versus time yields the flow rate of solid particulates in the animal's digestion. The animal is not harmed by the YbCl₃ since YbCl₃ is simply excreted in fecal matter and no change in body weight, organ weight, or hematocrit levels has been observed in mice.^[26]

The catalytic nature of YbCl₃ also has an application in DNA microarrays, or so called DNA “chips”.^[30] YbCl₃ led to a 50–80 fold increase in fluorescein incorporation into target DNA, which could revolutionize infectious disease detection (such as a rapid test for tuberculosis).^[30]

References

• Makerere University Library
• Makerere University Walter Reed Project
• Makerere University Walter Reed Project (MUWRP)
• Makereti
• Makereti Papakura
• Maker Hikōshiki Hatsune Mix
• Maker Media
• Maker movement
• Maker Movement
• Maker (musician)
• Make Room!!!!
• MakerPlane
• Maker (producer)
• Makers Academy
• Makers (Cory Doctorow novel)
• Makers culture
• Makers (magazine)
• Makers Of Melody
• Makers of Melody
• Makers of Memories
• Makers of Memories Foundation
• Maker space
• Maker's plate
• Makers' plate
• Makers Plate