7440-15-5 Usage
Description
Rhenium is a rare, silvery-white metal with a high melting point and exceptional physical and chemical properties. It is known for its strength, resistance to wear and high temperatures, and its ability to form stable compounds and alloys.
Uses
Used in Synthetic Chemistry:
Rhenium is used as a heterogeneous catalyst on 2.5mm alumina spheres for various chemical reactions, and it is also tested for ammonia synthesis.
Used in Steel and Alloy Industry:
Rhenium is used as an alloying element with iron to create steel that is hard, wear-resistant, and resistant to high temperatures. This makes it ideal for applications such as electrical contacts, switches, and high-temperature thermocouples.
Used in Aerospace and Defense:
Due to its high melting point and physical properties, rhenium alloys are used in rocket and missile engines, as well as in the filaments of photographic flash lamps.
Used in Nuclear Research:
Rhenium's isotope (187Re) has a very long half-life and decays at a steady rate, making it useful as a standard for measuring the age of the universe.
Used in Electronics and Semiconductors:
Rhenium is used in electron tubes, semiconductor applications, and as an alloy for electrical contacts. It also improves the workability of tungsten and molybdenum alloys.
Used in Miscellaneous Applications:
Rhenium is used for plating jewelry, medical instruments, high vacuum equipment, and mirror backings.
Isotopes
There are 45 isotopes of rhenium. Only one of these is stable: Re-185, whichcontributes 37.40% to the total amount of rhenium found on Earth. Re-187, which isradioactive with a very long half-life of 4.35×10+10 years, contributes 62.60% to rhenium’sexistence on Earth. The remaining 43 isotopes are radioactive with relatively shorthalf-lives and are artificially manufactured.
Origin of Name
Derived from the Latin word Rhenus, which stands for the Rhine River
in Western Europe.
Characteristics
Rhenium is one of the transition elements, which range from metals to metal-like elements.Its chemical and physical properties are similar to those of technetium, which is aboveit in the periodic table. It is not very reactive. When small amounts are added to molybdenum,it forms a unique type of semiconducting metal. It is also noncorrosive in seawater.
History
Discovery of rhenium is generally attributed to
Noddack, Tacke, and Berg, who announced in 1925 they had
detected the element in platinum ores and columbite. They also
found the element in gadolinite and molybdenite. By working
up 660 kg of molybdenite they were able in 1928 to extract 1 g
of rhenium. The price in 1928 was $10,000/g. Rhenium does
not occur free in nature or as a compound in a distinct mineral species. It is, however, widely spread throughout the Earth’s
crust to the extent of about 0.001 ppm. Commercial rhenium
in the U.S. today is obtained from molybdenite roaster-flue
dusts obtained from copper-sulfide ores mined in the vicinity
of Miami, Arizona, and elsewhere in Arizona and Utah.
Some molybdenites contain from 0.002 to 0.2% rhenium. It is
estimated that in 1999 about 16,000 kg of rhenium was being
produced. The total estimated world reserves of rhenium is
11,000,000 kg. Natural rhenium is a mixture of two isotopes,
one of which has a very long half-life. Thirty-nine other unstable
isotopes are recognized. Rhenium metal is prepared by
reducing ammonium perrhenate with hydrogen at elevated
temperatures. The element is silvery white with a metallic luster;
its density is exceeded by that of only platinum, iridium,
and osmium, and its melting point is exceeded by that of only
tungsten and carbon. It has other useful properties. The usual
commercial form of the element is a powder, but it can be
consolidated by pressing and resistance-sintering in a vacuum
or hydrogen atmosphere. This produces a compact shape in
excess of 90% of the density of the metal. Annealed rhenium
is very ductile, and can be bent, coiled, or rolled. Rhenium is
used as an additive to tungsten and molybdenum-based alloys
to impart useful properties. It is widely used for filaments for
mass spectrographs and ion gages. Rhenium-molybdenum alloys
are superconductive at 10 K. Rhenium is also used as an
electrical contact material as it has good wear resistance and
withstands arc corrosion. Thermocouples made of Re-W are
used for measuring temperatures up to 2200°C, and rhenium
wire has been used in photoflash lamps for photography.
Rhenium catalysts are exceptionally resistant to poisoning
from nitrogen, sulfur, and phosphorus, and are used for hydrogenation
of fine chemicals, hydrocracking, reforming, and
disproportionation of olefins. Rhenium has recently become
especially important as a catalyst for petroleum refining and
in making super-alloys for jet engines. Rhenium costs about
$16/g (99.99% pure). Little is known of its toxicity; therefore, it
should be handled with care until more data are available.
Production Methods
Among the compounds that can be formed with rhenium
are sulfides, fluorides, chlorides, bromides, iodides, and
oxides. Rhenium(VII) oxide, Re2O7, is the most stable
oxide of rhenium. It is formed from rhenium metal powder
or other rhenium oxides in dry air or an oxygen atmosphere
above 350° °C. Re2O7 is readily soluble in water, forming
perrhenic acid, HReO4, which forms salts (MReO4) such as
ammonium perrhenate (NH4ReO4). This is an important
starting material, which can be reduced to Re metal and
used for the production of many other rhenium compounds.
Rhenium can also form organometallic compounds such as
carbonyls (e.g., Re2(CO)10 and organorhenium compounds
such as hexamethylrhenium, Re(CH3)6.
Hazard
Flammable in powder form.
Hazard
Rhenium is flammable in powder form. Rhenium dust and powder and many of its compoundsare toxic when inhaled or ingested.
Flammability and Explosibility
Nonflammable
Check Digit Verification of cas no
The CAS Registry Mumber 7440-15-5 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 7,4,4 and 0 respectively; the second part has 2 digits, 1 and 5 respectively.
Calculate Digit Verification of CAS Registry Number 7440-15:
(6*7)+(5*4)+(4*4)+(3*0)+(2*1)+(1*5)=85
85 % 10 = 5
So 7440-15-5 is a valid CAS Registry Number.
InChI:InChI=1/Re
