ひ素 化学特性,用途語,生産方法
外観
灰黒色の小塊
性質
灰色ヒ素、黄色ヒ素（立方晶系、比重1.97）および黒色ヒ素（無定形、比重4.73）の3変態が知られる。四面体形四原子分子As4を含む黄色ヒ素はヒ素の蒸気を急冷してつくられる。しかし、すぐに金属光沢をもつ普通のヒ素すなわち灰色ヒ素または金属ヒ素とよばれる安定形に変わる。黄色ヒ素の構造は白リンと同じで、金属ヒ素は黒リンに似た構造をもち、いくらか導電性がある。空気中で熱すると三酸化二ヒ素を生じ、ハロゲンとも容易に反応する。濃硫酸・硝酸に溶けて亜ヒ酸、濃硝酸に溶けてヒ酸となる。酸素があると塩酸にも溶けて塩化ヒ素(Ⅲ)をつくる。アルシン（ヒ化水素）AsH3を熱分解すると黒色ヒ素を生じる。
溶解性
水に不溶。硝酸及び熱硫酸に溶けるが、塩酸にほとんど溶けない。また、水及び有機溶媒にもほとんど溶けない。
解説
As．原子番号33の元素．電子配置[Ar]3d104s24p3の周期表15族非金属元素．原子量74.92160(2)．安定核種が質量数75の同位体のみの単核種元素．ほかに60～92の放射性同位体がある．紀元前から硫化物などとして知られており，単体は13世紀の錬金術師Albertus Magnusがヒ素鉱物中に金属が含まれていることを認めていたが，1649年にJ. SchrÖderが酸化物を木炭で還元して，単体の分離にはじめて成功した．硫化物鉱物石黄の黄金色を表すアラビア語al-zarnikhがギリシアに入ってαρσενικον(arsenikon)となり，さらにラテン語名arsenicumにかわって，現在の英語の元素名arsenicとなった．宇田川榕菴は天保8年(1837年)に出版した「舎密開宗」で，亜爾攝𡰱"究母(アルセニキュム)砒としている．天然には，単体はまれに産出されるが，鶏冠石AsS，石黄As2S3，硫ヒ鉄鉱FeAsSなどが代表的な鉱物で，自然界に広く分布している．地殻中の存在度1.0 ppm．いん石(コンドライト)中にも ppm けたで存在する．非鉄金属製造で硫化鉱を処理するときに生じる煙灰中から回収し，加熱昇華で分離し，炭素で還元する．3種の同素体がある．室温で安定な灰色の金属ヒ素(α相)は三方晶系で，黒リンと同様の層状構造をしている．密度5.78 g cm－3(20 ℃)．第一イオン化エネルギー946.5 kJ mol－1(9.81 eV)．六配位の AsⅢおよび AsⅤのイオン半径はそれぞれ0.058，0.046 nm．加熱すると616 ℃ で昇華する．蒸気組成は四面体型 As4 で，急冷すると蒸気は凝縮して，密度4.70 g cm－3(20 ℃)，六方晶系の黄色ヒ素になるが，不安定で，光や放置，加熱で灰色の金属性ヒ素にかわる．転移の中間形が無定形の黒色ヒ素(β相)で，密度は4.6～5.2 g cm－3．ヒ素は酸化数3，5で化合物をつくる．水，希酸，アルカリ溶液には不溶，硝酸，濃硫酸にはH3AsⅢ O3やH3AsⅤ O4となって溶ける．乾燥した空気中で安定であるが，加熱すると燃えてAs2O3になる．空気を断って，硫黄Sやハロゲン X2 と加熱すると，それぞれAs2S3，AsX3(F2 ではAsF5)が生成する．多くの金属とは高温で直接反応し，ヒ化物を生じる．多くの有機ヒ素化合物があるが，重要なものにアルシン酸R2AsⅤO(OH)，アルソン酸RAsⅤO(OH)2(R：アルキル基，アリル基，ヘテロ環状基)とそれらの塩がある．メチルアルシン酸，ジメチルアルシン酸，フェニルアルソン酸，ジフェニルアルシン酸は農薬(除草剤)，医薬品に使用される．ジフェニルシアノアルシン，ジフェニルクロロアルシンはおう吐剤(旧日本軍化学兵器)．超高純度ヒ素は化合物半導体として需要最大のヒ化ガリウムGaAs製造に用いられる．亜ヒ酸塩，ヒ酸塩は殺虫剤(農薬)，防腐剤，なめし剤，なせんなどに使用される．そのほか，殺鼠剤，防蟻(ぎ)剤，除草剤，塗料，ガラス消泡剤に使用される．液晶ディスプレイガラス用がわが国の需要の大半を占めていたが，環境への配慮から無ヒ素化が進んでいる．合金への添加剤として，銅，鉛に添加すると硬さや耐食性が向上するので鉛蓄電池極板に使用される．毒性が強く，ヒ素，ヒ素化合物およびこれを含有する製剤は毒物劇物取締法の毒物に指定されている．PRTR法·特定第一種物質·発がん性クラス1，経口クラス2，作業環境クラス1．急性毒性の強さはアルシンAsH3がもっとも強く，亜ヒ酸塩がこれにつぐ．ヒ素化合物の致死量は1.5 mg/kg 体重(酸化ヒ素)．急性中毒症状は，腹痛，おう吐，下痢，筋肉痛など．亜ヒ酸塩は労働安全衛生法の特定化学物質．「ヒ素及びヒ素化合物」は水道法水質基準値ヒ素の量に関して0.01 mg/L 以下，水質汚濁防止法有害物質で排水基準値ヒ素の量に関して0.1 mg/L 以下，土壌汚染対策法特定有害物質で，基準値は同じくヒ素の量に関して土壌含有量150 mg/kg 以下である．[CAS 7440-38-2]
森北出版「化学辞典（第2版）
用途
半導体材料、合金材料、化合物製造原料。
用途
半導体原料
存在と製法
天然に遊離して産出することもあるが、雄黄（石黄）As2S3、鶏冠石As4S4、硫砒(りゅうひ)鉄鉱FeAsSなど、おもに硫化鉱物として存在する。そのほかにヒ華、単斜ヒ華などの酸化物やヒ化物などの鉱物が知られる。銅または鉛の製錬に際し副産物として得られる。硫化鉱を焙焼(ばいしょう)して三酸化二ヒ素As2O3とし、加熱昇華させて精製したのち、木炭で還元すると金属を得る。純度の高いものは、いったん塩化ヒ素とし、これを蒸留して精製してから、水素で還元してつくったヒ素を温度勾配(こうばい)をつけて電気炉中で昇華精製する。純度99.99999％以上のものが得られる。
用途
合金添加剤に用いられる。銅に少量加えると耐熱性を増し、鉛に加えると硬さを増すなどの特徴をもち、主として鉛‐アンチモン系の軸受合金などに添加される。最近は高純度ヒ素の用途が開けつつある。ヒ化ガリウムGaAs、ヒ化インジウムInAsなどの化合物半導体として、また半導体への添加剤として用いる。とくにGaAsは赤色あるいは赤外発光ダイオード、マイクロ波素子、集積回路、半導体レーザー、太陽電池などに用いられる。ヒ素の硫化物、高純度ヒ素の単結晶は赤外線をよく通すので赤外線写真用レンズ、フィルターなどに用いられる。
毒性
単体ヒ素には毒性がない（あるいは弱い）と考えられているが、ヒ素の化合物は有毒で農薬用に使われるが、生物への蓄積を恐れて他のものに置き換えられつつある。三酸化二ヒ素はガラスの透明度をあげたり脱色したりする目的で少量添加される。ヒ素化合物には強い毒性をもつものが多い。
説明
Arsenic is a metalloid of the nitrogen group. Two allotrope forms of elemental arsenic have been reported:
yellow arsenic and grey arsenic, the latter being usually the more stable form. Arsenic readily oxidises in
air to arsenic trioxide (As
2O
3). Arsenic is mostly found either in its native state or as arsenic sulfide in the
form of realgar (As
4S
4) or orpiment (As
2S
3). Arsenic can exist in three different valence states (zerovalent,
trivalent and pentavalent). Arsenic forms covalent bonds with carbon, oxygen and hydrogen. The toxicity
varies widely and depends on the physical state of the compound and its absorption/elimination rate.
Trivalent arsenics (As(III)) are derivatives of the arsenous acid (H
2AsO
3-arsenite) and arsenic trioxide
(AsO
3). Examples of pentavalent arsenic (As(V)) include derivatives of the arsenic acid (H
3AsO
4 -arsenate).
Organic arsenic-based compounds, that is, compounds containing arsenic-carbon bonds, are usually less
toxic than their inorganic counterparts. This is mainly due to their quicker excretion from the human body.
Arsenic is known to be one of the most toxic heavy metals. Compounds containing arsenic have a long
history of use as poisons, but they also have a long historical medicinal use.
化学的特性
Arsenic (As) is the third element in Group VA of the periodic table. Elemental arsenic can be found in two solid forms: yellow and gray or metallic, with specific gravities of 1.97 and 5.73, respectively (CRC, 1999). Gray arsenic is the ordinary stable form. Arsenic compounds can be categorized as inorganic and organic. Inorganic compounds do not contain an arsenic–carbon bond while organic compounds do.
物理的性質
Arsenic is classed as a semimetal, meaning that it is neither a metal like aluminum or lead,nor quite a nonmetal such as oxygen, sulfur, or chlorine. Arsenic’s main allotrope is a silverygray,brittle, metal-like substance. Its other two isotopes are unstable crystalline substances.
Gray arsenic exhibits an unusual property in that its boiling point (614°C) is lower than itsmelting point (817°C). As its temperature changes, it sublimates, which means it goes fromthe solid state, skipping the liquid state, into a vapor state. Cooling the vapor of sublimation,the black allotrope condenses out and in turn changes from the black to the gray allotrope. Ifyellow arsenic is rapidly cooled from its sublimation point, yellow arsenic will condense outand will not revert back to gray arsenic upon cooling.
The following information is for the gray semimetal form of arsenic only. Its melting pointis 817°C, its sublimation point varies between 613°C and 814°C depending on the atmosphericpressure, and its density is 5.776 g/cm
3.
同位体
There are a total of 35 isotopes of arsenic, ranging from As-60 to As-92, withhalf-lives spanning from a few nanoseconds to 80 days. Although some references claimthere are no stable isotopes of arsenic, arsenic-75 is classed as a stable isotope thatmakes up 100% of arsenic found in the Earth’s crust.
名前の由来
Derived either from the Latin word arsenicum or the Greek word arsenikon,
both meaning a yellow pigment. It is possible that the Arabic word azzernikh was
also an ancient name for arsenic.
天然物の起源
Arsenic is the 53rd most abundant element and is widely distributed in the Earth’s crust.It occurs naturally in several minerals, but high-grade deposits are rare. Most of the mineralsand ores that contain arsenic also contain other metals. Some major sources of arsenic are theminerals orpiment, scherbenkobalt, arsenopyrite, niccolite, realgar, gersdorffite, and smaltite.In addition, most sulfide ores of other metals also contain some arsenic. The three major mineralsthat produce arsenic are: realgar (arsenic monosulfide, AsS), orpiment (arsenic trisulfide,As
2S
2), and arsenopyrite (iron arsenosulfide, FeAsS).
Today, most arsenic is recovered as a by-product from the smelting of nickel, copper, iron,and tin. It is also recovered from the flue dust of copper- and lead-smelting furnaces.
特性
Arsenic in the elemental form is a brittle, grayish crystal that becomes darker when exposedto air. It is seldom found in the pure elemental form but rather in minerals (compounds). Ithas a long history of use as a poison, and many alchemists were poisoned when using it intheir attempts to produce gold from base metals.
Arsenic has limited commercial use.
使用
Arsenic is a brittle solid with a metallic coloring that ranges from silver to gray. It is a naturally occurring element found in the earth’s crust, and it cycles rapidly through water, land, air, and living systems. Exposure to it occurs through ingestion, inhalation, and dermal contact.
The arsenic metalloid is used for hardening copper and lead alloys (HSDB, 2005). It is also used in glass manufacturing as a decolorizing and refining agent, as a component of electrical devices in the semiconductor industry, and as a catalyst in the production of ethylene oxide. Arsenic compounds are used as a mordant in the textile industry, for preserving hides, as medicinals, pesticides, pigments, and wood preservatives. The production of chromate copper arsenate (CCA), a wood preservative, accounts for approximately 90% of the domestic arsenic consumption (ATSDR, 2007). However, production of this preservative is being phased out. The uses of inorganic arsenical compounds (e.g., lead arsenate) as pesticides were voluntarily cancelled by the industry during late 1980s and early 1990s. A majority of organoarsenicals are used on cotton and turf as herbicides. disodium methanearsenate (DSMA), monosodium methanearsenate (MSMA), and calcium methanearsenate (CAMA) continue to be used as contact herbicides.
定義
A toxic metalloid element existing in
several allotropic forms; the most stable is
a brittle gray metal. It belongs to group 15
(formerly VA) of the periodic table. Arsenic
is found native and in several ores including
mispickel (FeSAs), realgar (As
4S
3),
and orpiment (As
2S
3). The element reacts
with hot acids and molten sodium hydroxide
but is unaffected by water and acids
and alkalis at normal temperatures. It is
used in semiconductor devices, alloys, and
gun shot. Various compounds are used in
medicines and agricultural insecticides and
poisons.
Symbol: As; m.p. 817°C (gray) at 3
MPa pressure; sublimes at 616°C (gray);
r.d. 5.78 (gray at 20°C); p.n. 33; r.a.m.
74.92159.
一般的な説明
A grayish metallic solid that turns black upon exposure to air. Insoluble in water. Toxic by ingestion.
空気と水の反応
Turns black on exposure to air. Insoluble in water.
反応プロフィール
Arsenic reacts incandescently with bromine trifluoride, even at 10°C [Mellor 2:113 1946-47]. Causes bromoazide to explode upon contact. Ignites if ground up together with solid potassium permanganate [Mellor 12:322 1946-47]. Is oxidized by sodium peroxide with incandescence [Mellor 2:490-93 1946-47]. A combination of finely divided Arsenic with finely divided bromates (also chlorates and iodates) of barium, calcium, magnesium, potassium, sodium, or zinc can explode by heat, percussion, and friction [Mellor 2:310 1946-47]. Bromine pentafluoride reacts readily in the cold with Arsenic. Ignition usually occurs. Reacts vigorously with fluorine at ordinary temperatures [Mellor 9:34 1946-47].
危険性
Most of the compounds of arsenic are toxic when in contact with the skin, when inhaled,or when ingested. As with arsenic’s cousin phosphorus above it in group 15 of the periodictable, care must be taken when using arsenic. The compound arsenic trioxide (As
2O
3), anexcellent weed-killer, is also carcinogenic. Copper acetoarsenite, known as Paris green, is usedto spray cotton for boll weevils. A poisonous dose of arsenic as small as 60 milligrams can bedetected within the body by using the Marsh test.
工業用途
Arsenic (symbol As) is a soft, brittle, poisonouselement of steel-gray color and metallic luster.In atomic structure it is a semimetal, lackingplasticity, and is used only in alloys and incompounds. The bulk of the arsenic used isemployed in insecticides, rat poisons, and weedkillers, but it has many industrial uses, especiallyin pigments. It is also used in poisongases for chemical warfare.Metallic arsenic is stable in dry air. Whenexposed to humid or moistened air, the surfacefirst becomes coated with a superficial goldenbronze tarnish, which on further exposure turnsblack. On heating in air arsenic will vaporizeand burn to As2O3.
安全性プロファイル
Confirmed human
carcinogen producing liver tumors. Poison
by subcutaneous, intramuscular, and
intraperitoneal routes. Human systemic skin
and gastrointestinal effects by ingestion. An
experimental teratogen. Other experimental
reproductive effects. Mutation data
reported. Flammable in the form of dust
when exposed to heat or flame or by
chemical reaction with powerful oxidizers
such as bromates, chlorates, iodates,
peroxides, lithium, NC4, m 0 3 , Khfn04,
Rb2C2, AgN04, NOCl, IF5, CrO3, CIF3,
Cl0, BrF3, BrFj, BrN3, RbGBCH,
CsC3BCH. Slightly explosive in the form of
dust when exposed to flame. When heated
or on contact with acid or acid fumes, it
emits highly toxic fumes; can react
vigorously on contact with oxidizing
materials. Incompatible with bromine azide,
dirubidium acetylide, halogens, palladium,
zinc, platinum, NCh, AgNO3, CrO3, Na2O2,
hexafluoroisopropylideneamino lithum.
職業ばく露
Arsenic compounds have a variety of
uses. Arsenic and its compounds are used as an alloy additive,
in electronic devices; in veterinary medicines; in agriculture
as insecticides, herbicides, larvicides, and
pesticides. Some arsenic compounds are used in pigment
production; the manufacture of glass as a bronzing or
decolorizing agent; the manufacture of opal glass and
enamels, textile printing; tanning, taxidermy, antifouling
paints; to control sludge formation in lubricating oils.
Metallic arsenic is used as an alloying agent for heavy
metals; and in solders, medicines, herbicides. EPA has estimated
that more than 6 million people living within 12 mi
of major sources of copper, zinc, and lead smelters-may be
exposed to 10 times the average United States atmospheric
levels of arsenic. The agency says that 40,000 people living
near some copper smelters may be exposed to 100 times
the national atmospheric average.
発がん性
Arsenic and inorganic arsenic compounds are known to be human carcinogens based on sufficient evidence of carcinogenicity in humans.
環境運命予測
Trivalent arsenic exerts its toxic effects mainly by disrupting
ATP production by inhibiting lipoic acid, which is a cofactor for
pyruvate as well by replacing phosphate which uncouples
oxidation phosphorylation. This inhibits the electron transport
chain in the mitochondria and the ultimate synthesis of ATP.
Hydrogen peroxide production is also increased, which, it is
speculated, has potential to form reactive oxygen species and
oxidative stress. These metabolic interferences lead to death
from multisystem cell death and organ failure. The activity of
enzymes is due to the functional groups on amino acids such as
the sulfhydryl group on cysteine or coenzymes such as lipoic
acid, which has vicinal thiol groups. Trivalent inorganic
arsenicals readily react with sulfhydryl groups such as cysteine
creating a strong complex between arsenic and vicinal sulfhydryl
reagents. These actions inhibit not only the formation of
Acetyl-CoA but also the enzymes succinic dehydrogenase and
pyruvate. Arsenite inhibits the binding of steroids to the
glucocorticoid receptor, but not other steroid receptors. The
probable mechanism of toxicity of pentavalent inorganic
arsenate is its reduction to a trivalent form, arsenite, which is
more toxic than the arsenate. Thus, a variety of mechanisms
lead arsenic to impair cell respiration and subsequently
diminish ATP formation.
輸送方法
UN1558 Arsenic, Hazard Class: 6.1; Labels:
6.1-Poisonous materials.
不和合性
Incompatible with strong acids; strong
oxidizers; peroxides, bromine azide, bromine pentafluoride,
bromine trifluoride; cesium acetylene carbide, chromium
trioxide; nitrogen trichloride, silver nitrate. Can react vigorously
with strong oxidizers (chlorine, dichromate, permanganate).
Forms highly toxic fumes on contact with acids or
active metals (iron, aluminum, zinc). Hydrogen gas can
react with inorganic arsenic to form highly toxic arsine gas.
廃棄物の処理
Elemental arsenic wastes
should be placed in long-term storage or returned to
suppliers or manufacturers for reprocessing. Arsenic
pentaselenide-wastes should be placed in long-term storage
or returned to suppliers or manufacturers for reprocessing.
Arsenic trichloride: hydrolyze to arsenic trioxide utilizing
scrubbers for hydrogen chloride abatement. The trioxide
may then be placed in long-term storage. Arsenic trioxide:
long-term storage in large shiftproof and weatherproof
silos. This compound may also be dissolved, precipitated as
the sulfide and returned to the suppliers. Arsenic-containing
sewage may be decontaminated by pyrolusite treatment.
Consult with environmental regulatory agencies for guidance
on acceptable disposal practices. Generators of waste
containing this contaminant (≥100 kg/mo) must conform
with EPA regulations governing storage, transportation,
treatment, and waste disposal. In accordance with
40CFR165, follow recommendations for the disposal of
pesticides and pesticide containers. Must be disposed properly
by following package label directions or by contacting
your local or federal environmental control agency, or by
contacting your regional EPA office.
ひ素 上流と下流の製品情報
原材料
準備製品