Beryllium, Magnesium, and Calcium

Beryllium, Magnesium, and Calcium. - The toxic effects of beryllium salts and organoberyllium derivatives have limited the use of this element in synthetic laboratories. However a number of organoberyllium reagents (116-119) have been evaluated in terms of their ability to effect the asymmetric reduction of prochiral ketones. Secondary alcohols have been obtained in up to 42%e.e. using these derivatives. 7  

Oppolzer has continued to develop the magnesium-ene reaction, and has reported on the application of this useful cyclisation procedure 

The phosphonate derivative (122) has been prepared as an alternative source of the diethoxyphosphinyl carbanion, and the reactivity of the organomagnesium reagent has been compared with the more commonly used organolithium species.7 An improved preparation of CH2(MgBr)2 has also been reported. 75 77 78 Hart has extended his studies 

The intermediates can also be trapped with Me,SiCl, and N,N-dialkyl- 

Other developments in this area include the use of magnesium-graphite, generated from potassium-graphite (CgK) and magnesium chloride in tetrahydrofuran, for the pinacol coupling of aldehydes and 

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Consequently, they maintain that some displays of the periodic system may, in truth, be superior to others. Whereas the conventionally displayed table, called the medium-long form, has many virtues, it places helium among the noble-gas elements. Some have argued that in spite of appearances, helium should in fact be placed el the head of group 2, the alkaline earth group, which includes beryllium, magnesium and calcium. Helium has two outer-shell electrons as do the elements in the alkaline earth group. 

In Table XVIII are given values of the radius ratio for the salts of beryllium, magnesium and calcium (those of barium and strontium, with the sodium chloride structure, also obviously satisfy the radius ratio criterion). It is seen that all of the sodium chloride type crystals containing eight-shell cations have radius ratios greater than the limit 0.33, and the beryl-... 

A similar but less complete trend appears in the reactions of the alkaline earth metals with oxygen. Treatment with excess 02 yields monoxides in the cases of beryllium, magnesium, and calcium barium, however, forms the peroxide, Ba02, whereas strontium gives a mixture of monoxide and peroxide. 

The group IIA(2) elements are beryllium, magnesium, and calcium. Each has two electrons in the valence shell. The group IIIA(13) elements are boron and aluminum. Both have three electrons in the valence shell. The group IVA(14) elements are carbon and silicon each has four valence-shell electrons. 

Look now at the configurations of beryllium, magnesium, and calcium, members of the group of alkaline earth metals (Group IIA), which are similar, moderately reactive elements. 

Alkali metal salts are effective promoters in the direct process. Improved synthesis of MeaSiCla has been claimed in the presence of copper, tin and zinc and either KCl or CsCl . Alkah earth metals are also effective promoters. Beryllium, magnesium and calcium were claimed to improve the selectivity for Di in the MCS reaction. For example, a mixmre of silicon (210 g), CuCl (16.4 g), CaCl2 (1.244 g), ZnCl2 (1.53 g) and bronze (2% Sn, 2.0 g) was pre-activated at 200 °C under nitrogen, whereupon MeCl was fed in at 16-27 Lh" at 330-345 °C for 15.5 h to give 55% conversion of Si and 86.7% selectivity to Me2SiCl2. ... 

Group II consists of the five metals beryllium, magnesium, calcium, strontium and barium, and the radioactive element radium. Magnesium and calcium are generally available for use in school. These metals have the following properties. 

The second column from the left contains the alkaline earth metals, beryllium, magnesium, calcium, strontium, barium, and radium (Be, Mg, Ca, Sr, Ba, and Ra, respectively). Magnesium and calcium are present everywhere and are needed by our salty bodies and the salty bodies of our fellow creatures. Calcium is vital to bones, teeth, seashells, and exoskeletons. Calcium plays a critical role in the operation of our muscles as well as communication between cells. Because strontium is in this family, radioactive strontium, a fission product of certain atomic reactions, can be absorbed by the body and used as it would use calcium. Radium, another radioactive element, is also found in this family. 

King, J.R. 2002 The evolution of Galactic beryllium and boron traced by magnesium and calcium. 2002 PASP 114, 25. 

Bis(A-alkylsalicylaldiminato)beryllium complexes (54) have been prepared and their physicochemical properties studied. Dipole momenr and NMR studies are interpreted in terms of a tetrahedral environment for the beryllium. NMR studies on the magnesium and calcium analogues are similarly interpreted. The free energy of enantiomerization has been determined for (54 R = isopropyl) using NMR techniques and without needing resolution of the mtical antipodes the inversion has been proposed as proceeding via a dimerization step. The fluorescent properties of a range of beryllium chelates have been monitored with a... 

CaS04 2 H2O) in plasters to decorate their tombs. These two alkaline earths are among the most abundant elements in the Earth s crust (calcium is fifth and magnesium sixth, by mass), and they occur in a wide variety of minerals. Strontium and barium are less abundant but like magnesium and calcium, they commonly occur as sulfates and carbonates in their mineral deposits. Beryllium is fifth in abundance of the alkaline earths and is obtained primarily from the mineral beryl, 863 2(8103)6. All radium isotopes are radioactive (the longest lived isotope is Ra, with a half-life of 1600 years). Pierre and Marie Curie first isolated radium from the uranium ore pitchblende in 1898. Physical properties of the alkaline earths are given in Table 8.4. 

All the cations form complexes with oxygen, nitrogen donor ligands (see Chapter 15), and also with the lighter halides. Beryllium (Be) is limited to a maximum coordination number of four due to its small size (more than four atoms just can t fit around it ). Magnesium and calcium can be six coordinate, and strontium and barium can have even higher coordination numbers. 

Beryllium occurs principally as the silicate mineral beryl, Be3Al2[Si60i8] (silicates, see Section 14.9). It is also found in many natural minerals, and precious forms include emerald and aquamarine. Magnesium and calcium are the eighth and fifth most abundant elements, respectively, in the Earth s crust, and Mg is the third most abundant in the... 

Kaufman Katz A, Glusker JP, Beebe SA, Bock CW (1996) Calcium ion coordination a comparison with that of beryllium, magnesium, and zinc. J Am Chem Soc 118 5752-5763. doi 10.1021/ja953943i... 

Group IIB and know that this means the group of elements zine. cadmium and mercury, whilst Group IIA refers to the alkaline earth metals beryllium, magnesium, calcium, barium and strontium. 

The Elements Beryllium (Be), Magnesium (Mg), and Calcium (Ca) all formed oxides in fhe ratio of one afom per oxygen atom RO Boron (B) and Aluminum (Al) formed R2O3 Carbon (C) and Silicon (Si) formed RO2... 

Magnesium [7439-95-4] atomic number 12, is in Group 2 (IIA) of the Periodic Table between beryllium and calcium. It has an electronic configuration of 1T2T2 3T and a valence of two. The element occurs as three isotopes with mass numbers 24, 25, and 26 existing in the relative frequencies of 77, 11.5, and 11.1%, respectively. 

Beryllium, Magnesium, Calcium, Strontium, Barium and Radium... 

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