Boron CAS:7440-42-8

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Boron CAS:7440-42-8

Boron CAS:7440-42-8 Basic information

Product Name: Boron
Synonyms: B Target 99.9%;DNA pol εBoron powder, crystalline, -4+40 mesh, Puratronic, 99.9999% (metals basis);Boron powder, crystalline (99.5%);Boron, amorphous powder -325 mesh 90%;Boron 99.99%;3-(1-Methylethyl)-2,1,3-benzothiadiazin-4(3H)-one-13C6 2,2-Dio
CAS: 7440-42-8
MW: 10.81
EINECS: 231-151-2
Product Categories: metal or element;Boron;Catalysis and Inorganic Chemistry;Chemical Synthesis;Electronic Chemicals;Micro/Nanoelectronics;Pure Elements;Industrial/Fine Chemicals;Inorganics
Mol File: 7440-42-8.mol

Boron CAS:7440-42-8 Chemical Properties

density: 2.34 g/mL at 25 °C(lit.)
Melting point: 2300°C
Boiling point: 2550°C
form: pieces
storage temp.: Storage temperature: no restrictions.
Water Solubility: insoluble H2O [MER06]
solubility: H2O: soluble
NIST Chemistry Reference: Boron(7440-42-8)
Merck: 13,1333
Stability: Stable. Substances to be avoided include strong oxidizing agents and strong acids. May decompose on exposure to air - store under nitrogen. Highly flammable.
Specific Gravity: 2.34~2.37
optical activity: [α]20/D 1°, neat
Hydrolytic Sensitivity: 8: reacts rapidly with moisture, water, protic solvents
CAS DataBase Reference: 7440-42-8(CAS DataBase Reference)
EPA Substance Registry System: Boron (7440-42-8)



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Boron Usage And Synthesis
DescriptionBoron was discovered by Sir Humphry Davy and J.L. Gay-Lussac in 1808. It is a trivalent non-metallic element that occurs abundantly in the evaporite ores borax and ulexite. Boron is never found as a free element on Earth. Boron appears as charcoal-grey pieces or black powder or as crystalline; is a very hard, black material with a high melting point; and exists in many polymorphs.
Boron has several forms, and the most common one is amorphous boron, a dark powder, non-reactive to oxygen, water, acids, and alkalis. It reacts with metals to form borides. Boron is an essential plant micronutrient. Sodium borate is used in biochemical and chemical laboratories to make buffers. Boric acid is produced mainly from borate minerals by the reaction with sulphuric acid. Boric acid is an important compound used in textile products. The most economically important compound of boron is sodium tetraborate decahydrate or borax, used for insulating fibreglass and sodium perborate bleach. Compounds of boron are used in organic synthesis, in the manufacture of a particular type of glasses, and as wood preservatives. Boron filaments are used for advanced aerospace structures, due to their high strength and light weight.
Chemical PropertiesBoron is a trivalent, nonmetallic element that occurs abundantly in the evaporite ores, borax and ulexite. Boron is never found as a free element on Earth. Boron as a crystalline is a very hard, black material with a high melting point, and exists in many polymorphs. Boron has several forms, the most common form being amorphous boron, a dark powder, non-reactive to oxygen, water, acids, and alkalis. It reacts with metals to form borides. Boron is an essential plant micronutrient. Sodium borate is used in biochemical and chemical laboratories to make buffers. Boric acid is produced mainly from borate minerals by the reaction with sulfuric acid. Boric acid is an important compound used in textile products. Compounds of boron are used in organic synthesis, in the manufacture of special types of glasses, and as wood preservatives. Boron fi laments are used for advanced aerospace structures owing to their high strength and light weight. It is used as an antiseptic for minor burns or cuts and is sometimes used in dressings. Boric acid was fi rst registered in the United States in 1948 as an insecticide for control of cockroaches, termites, fireants, fleas, silverfish, and many other insects. It acts as a stomach poison affecting the insects' metabolism, and the dry powder is abrasive to the insects' exoskeleton. Boric acid is generally considered to be safe for use in household kitchens to control cockroaches and ants. The important use of metallic boron is as boron fiber. Borate-containing minerals are mined and processed to produce borates for several industrial uses, i.e., glass and ceramics, soaps and detergents, fire retardants and pesticides. The fibers are used to reinforce the fuselage of fi ghter aircraft, e.g., the B-1 bomber. The fibers are produced by vapor deposition of boron on a tungsten fi lament. Pyrex is a brand name for glassware, introduced by Corning Incorporated in 1915. Originally, Pyrex was made from thermal shock-resistant borosilicate glass.
Chemical PropertiesBoron is a yellow or brownish-black powder and may be either crystalline or amorphous. It does not occur free in nature and is found in the minerals borax, colemanite, boronatrocalcite, and boracite. It is insoluble in water but soluble in nitric and sulfuric acids. It is insoluble in cold water, hot water, diethyl ether, and alcohol. If finely divided, it is soluble in most molten metals such as copper, iron, magnesium, aluminum, and calcium. Borates are relatively soluble in water.
Physical propertiesBoron has only three electrons in its outer shell, which makes it more metal than nonmetal.Nonmetals have four or more electrons in their valence shell. Even so, boron is somewhatrelated to metalloids and also to nonmetals in period 2.
It is never found in its free, pure form in nature. Although less reactive than the metalswith fewer electrons in their outer orbits, boron is usually compounded with oxygen andsodium, along with water, and in this compound, it is referred to as borax. It is also found asa hard, brittle, dark-brown substance with a metallic luster, as an amorphous powder, or asshiny-black crystals.
Its melting point is 2,079°C, its boiling point is 2,550°C, and its density is 2.37 g/cm3.
IsotopesThere are a total of 13 isotopes of boron, two of which are stable. The stableisotope B-10 provides 19.85% of the element’s abundance as found in the Earth’s crust,and the isotope B-11 provides 80.2% of boron’s abundance on Earth.
Origin of NameIt is named after the Arabic word bawraq, which means “white borax.”
OccurrenceBoron is the 38th most abundant element on Earth. It makes up about 0.001% of theEarth’s crust, or 10 parts per million, which is about the same abundance as lead. It is notfound as a free element in nature but rather in the mineral borax, which is a compound ofhydrated sodium, hydrogen, and water. Borax is found in salty lakes, dry lake-beds, or alkalisoils. Other naturally occurring compounds are either red crystalline or less dense, dark-brownor black powder.
Boron is also found in kernite, colemanite, and ulexite ores, and is mined in many countries,including the western United States.
CharacteristicsBoron is a semimetal, sometimes classed as a metallic or metalloid or even as a nonmetal.It resembles carbon more closely than aluminum. Although it is extremely hard in its purified form—almost as hard asdiamonds—it is more brittle than diamonds, thus limiting its usefulness. It is an excellentconductor of electricity at high temperatures, but acts as an insulator at lower temperatures.
HistoryBoron compounds have been known for thousands of years, but Boron was not discovered until 1808 by Sir Humphry Davy and by Gay-Lussac and Thenard. The element is not found free in nature, but occurs as orthoboric acid usually in certain volcanic spring waters and as borates in borax and colemanite. Ulexite, another boron mineral, is interesting as it is nature’s own version of “fiber optics.” Important sources of boron are the ores rasorite (kernite) and tincal (borax ore). Both of these ores are found in the Mojave Desert. Tincal is the most important source of boron from the Mojave. Extensive borax deposits are also found in Turkey. Boron exists naturally as 19.9% 10B isotope and 80.1% 11B isotope. Ten other isotopes of boron are known. High-purity crystalline boron may be prepared by the vapor phase reduction of boron trichloride or tribromide with hydrogen on 4-6 The Elements electrically heated filaments. The impure, or amorphous, boron, a brownish-black powder, can be obtained by heating the trioxide with magnesium powder. Boron of 99.9999% purity has been produced and is available commercially. Elemental boron has an energy band gap of 1.50 to 1.56 eV, which is higher than that of either silicon or germanium. It has interesting optical characteristics, transmitting portions of the infrared, and is a poor conductor of electricity at room temperature, but a good conductor at high temperature. Amorphous boron is used in pyrotechnic flares to provide a distinctive green color, and in rockets as an igniter. By far the most commercially important boron compound in terms of dollar sales is Na2B4O7 · 5H2O. This pentahydrate is used in very large quantities in the manufacture of insulation fiberglass and sodium perborate bleach. Boric acid is also an important boron compound with major markets in textile fiberglass and in cellulose insulation as a flame retardant. Next in order of importance is borax (Na2B4O7 · 10H2O) which is used principally in laundry products. Use of borax as a mild antiseptic is minor in terms of dollars and tons. Boron compounds are also extensively used in the manufacture of borosilicate glasses. The isotope boron-10 is used as a control for nuclear reactors, as a shield for nuclear radiation, and in instruments used for detecting neutrons. Boron nitride has remarkable properties and can be used to make a material as hard as diamond. The nitride also behaves like an electrical insulator but conducts heat like a metal. It also has lubricating properties similar to graphite. The hydrides are easily oxidized with considerable energy liberation, and have been studied for use as rocket fuels. Demand is increasing for boron filaments, a high-strength, lightweight material chiefly employed for advanced aerospace structures. Boron is similar to carbon in that it has a capacity to form stable covalently bonded molecular networks. Carboranes, metalloboranes, phosphacarboranes, and other families comprise thousands of compounds. Crystalline boron (99.5%) costs about $6/g. Amorphous boron (94–96%) costs about $1.50/g. Elemental boron and the borates are not considered to be toxic, and they do not require special care in handling. However, some of the more exotic boron hydrogen compounds are definitely toxic and do require care.
UsesBoron has found many uses and has become an important industrial chemical. Boron is used as an alloy metal, and when combined with other metals, it imparts exceptional strength to those metals at high temperatures. It is an excellent neutron absorber used to capture neutrons in nuclear reactors to prevent a runaway fission reaction. As the boron rods are lowered into the reactor, they control the rate of fission by absorbing excess neutrons. Boron is also used as an oxygen absorber in the production of copper and other metals, Boron finds uses in the cosmetics industry (talc powder), in soaps and adhesives, and as an environmentally safe insecticide. A small amount of boron is added as a dope to silicon transistor chips to facilitate or impede the flow of current over the chip. Boron has just three valence electrons; silicon atoms have four. This dearth of one electron in boron s outer shell allows it to act as a positive hole in the silicon chip that can be filled or left vacant, thus acting as a type of switch in transistors. Many of today s electronic devices depend on these types of doped-silicon semiconductors and transistors. Boron is also used to manufacture borosilicate glass and to form enamels that provide a protective coating for steel. It is also used as medication for relief of the symptoms of arthritis. Due to boron s unique structure and chemical properties, there are still more unusual compounds to be explored.
UsesAs early as 1959, boron filaments were introduced as the first of a family of high-strength, high-modulus, low-density reinforcements developed for advanced aerospace applications. A process was engineered by Avco Specialty Materials (Lowell, Massachusetts) and the U.S. Air Force to manufacture boron filaments that had high strength and high stiffness, but low density and, hence, low weight. During the interim, advanced boron fibers have been used as a reinforcement in resin-matrix composites. Boron aluminum has been used for tube-shaped truss members, for reinforcing space vehicle structures, and has also been considered as a fan blade material for turbofan jet engines.These shortcomings led to the development of silicon-carbide (SiC) fibers for some applications.
The principal use of boron filaments is in the form of continuous boronepoxy pre-impregnated tape, commonly known as prepreg. Usually, the resin content is about 30–35% (weight). Boron composites have been used in military aircraft, including helicopters. In addition to aircraft, boron-epoxy composites have been used in tennis, racquetball, squash, and badminton rackets, fishing rods, skis, and golf club shafts, for improving strength and stiffness.
Boron has been used in cutting and grinding tools. Boron is 30–40% harder than silicon carbide and almost twice as hard as tungsten carbide. Boron also has interesting microwave polarization properties. Research (Southern Illinois University) has shown that a single ply of boron epoxy will transmit 98.5% and reflect 0.6% of the incident microwave power when the angle between the grain and the E-field is 90°. This property has been useful in the design of spacecraft antennas and radomes.

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