Oxoacids - Oxoanes

[ I ] Inorganic compounds (oxoacids): Also called oxygen acids or oxyacids. In compounds XOn(OH) _m , an O atom is bonded to the central atom X, and all or some of the O atoms are _bonded to H atoms. The H atom dissociates into H ⁺ as a protonic acid, producing an oxoanion. X is usually a nonmetallic element. When there are many H atoms that can dissociate in an acid, the degree of dissociation of the second and third H atoms is generally much smaller than that of the first H atom. Also, several molecules of the same oxoacid may condense to form an isopolyacid, or several types of oxoacids may condense to form a heteropolyacid. Even if the same central atom X is contained, there are generally many types of oxoacids. In this case, the one with the most common oxidation number of X is named after the element name of X followed by the acid. For example, bromic acid, _HBrO3 . However, there are exceptions, such as sulfuric acid with S, arsenic acid with As, and nitric acid with N. Previously, when the oxidation number of X was higher than the most common oxidation number, it was differentiated by adding the prefixes hyper, sub, hypo, etc. when it was lower, and further by adding the prefix pyro for ortho, meta, and poly acids when necessary. Some of these names still remain today. However, since it is not wise to apply this to all acids and increase the number of new names of this kind, the IUPAC nomenclature proposes a hydrogen nomenclature and acid nomenclature that are common to all acids, and these prefixes are permitted to be used only for limited purposes. For example, sulfurous acid _H2SO3 is an acceptable name, but in the hydrogen nomenclature _it is called trioxosulfuric acid (2-) dihydrogen, and in the acid nomenclature it is called trioxosulfuric acid (IV). [ II ] Organic compound (oxo acid): An organic compound in which an O atom is substituted for the C atom of the skeletal carbon chain of a carboxylic acid. In other words, it refers to aldehyde acids and keto acids that have a carbonyl group in addition to a carboxyl group. For example,

OHC-CH ₂ CH ₂ COOH, CH ₃ -CO-CH ₂ COOH

And so on.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

【Ⅰ】無機化合物(oxoacid)：酸素酸(oxygen acid)，オキシ酸(oxyacid)ともいう．中心原子XにOが結合し，そのO原子の全部または一部にH原子が結合した化合物XO_n(OH)_mで，そのH原子はプロトン酸として H^＋ に解離し，オキソアニオンを生じる．Xは普通は非金属元素である．ある酸で解離しうるH原子が多数ある場合は，一般に第一のH原子の解離度に比べ，第二，第三のH原子の解離度はずっと小さくなる．また，数分子の同じオキソ酸が縮合してイソポリ酸を形成したり，数種類のオキソ酸が縮合してヘテロポリ酸を形成することもある．同じ中心原子Xを含むものでも，一般に多種類のオキソ酸が存在する．この場合，Xがもっとも普通の酸化数のものに，Xの元素名に酸を付けた名称をつける．たとえば，臭素酸HBrO₃．ただし，Sの硫酸，Asのヒ酸，Nの硝酸などは例外である．以前はXの酸化数が，もっとも普通の酸化数より大きいときは過，小さいときは順次，亜，次亜などを付け，さらに必要な場合にオルト，メタ，ポリ酸ではピロなどを付けて区別した．それらの命名は現在もいくつかは残っている．しかし，すべての酸に適用してこの種の新名称を増やしていくのは得策ではないため，IUPAC命名法では，すべての酸に共通する水素命名法，酸命名法が提唱され，これらの接頭語は限られたものだけに使用を許すとしている．たとえば，亜硫酸H₂SO₃は許容された名称であるが，水素命名法では，トリオキソ硫酸(2－)二水素，酸命名法では，トリオキソ硫(Ⅳ)酸という．【Ⅱ】有機化合物(oxo acid)：カルボン酸の骨格炭素鎖のC原子にO原子を置換導入したもの．つまり，カルボキシル基以外に，カルボニル基も有するアルデヒド酸やケト酸のことをいう．たとえば，

OHC-CH₂CH₂COOH，CH₃-CO-CH₂COOH

などである．

出典　森北出版「化学辞典（第2版）」化学辞典 第2版について　情報