vmelkon
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Other acids than oxyacids
We see HNO3, H2SO4, HClO4 often in textbooks but do other exotic acids exist?
I am thinking of Arrhenius acids.
There is something called magic acid
http://en.wikipedia.org/wiki/Magic_acid
but again, you have a H and O bond.
Fluoroantimonic acid (H2FSbF6) looks interesting.
How about something like H2SeS4 (equivalent to H2SO4)?
H3PS4? (equivalent to H3PO4)
H3AsS4 (equivalent to H3AsO4)
O 3.44
N 3.04
S 2.58
Cl 3.16
P 2.19
As 2.18
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We must attach the electrodes of knowledge to the nipples of ignorance and give a few good jolts.
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Etaoin Shrdlu
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Define "exotic acid." I'm not really sure where you're going with this.
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Amos
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Non-oxoacids? How about HF, HCl, HBr, HI, H2S, HN3(hydrazoic acid), and HCN(hydrogen cyanide or prussic acid)? Orare you just looking for "exotic"
lesser-known acids in general?
This may also interest you: http://en.wikipedia.org/wiki/Thiophosphate
Selenophosphate, a dihydrogen phosphate ion in which the oxygen double bonded to phosphorus is replaced by selenium, is of biological importance in
that it is used to biosynthesize selenocysteine, an unusual amino acid.
Section 2.4 of this paper mentions the synthesis of sodium thioarsenate (Na3AsS4), which would be the sodium salt of one of the
acids you mentioned.
[Edited on 3-12-2015 by Amos]
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vmelkon
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I wasn't clear with the question. I was wondering if molecules where the O is replaced with something else in its group, such as sulfur, have been
produced.
Signature ==== Is this my youtube page? https://www.youtube.com/watch?v=tA5PYtul5aU
We must attach the electrodes of knowledge to the nipples of ignorance and give a few good jolts.
Yes my evolutionary friends. We are all homos here. |
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Amos
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I updated the post above with some new stuff.
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vmelkon
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Thanks. It's good to know and knowing is half the battle.
Signature ==== Is this my youtube page? https://www.youtube.com/watch?v=tA5PYtul5aU
We must attach the electrodes of knowledge to the nipples of ignorance and give a few good jolts.
Yes my evolutionary friends. We are all homos here. |
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bismuthate
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http://en.wikipedia.org/wiki/Thiosulfuric_acid
Although a big problem is that sulfides tend to react in acidic environments.
There are also chlacogen-cyanates which are rather common.
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PHILOU Zrealone
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Nitroform HC(NO2)3
Phenol HO-C6H5
Cyanoform HC(C#N)3
Trinitroaniline H2N-C6H2(NO2)3
Tetrazole cyclo(-CH=N-N=N-NH-)
Nitrotetrazole cyclo(-C(NO2)=N-N=N-NH-)
[Edited on 14-3-2015 by PHILOU Zrealone]
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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unionised
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http://en.wikipedia.org/wiki/Thiophosphate
http://en.wikipedia.org/wiki/Thiocarboxylic_acid
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blogfast25
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Hexachlorostannic acid, H<sub>2</sub>SnCl<sub>6</sub>, a strong acid from which a crystalline hydrate can be isolated, acc.
Holleman ('Inorganic Chemistry'). Ammonium and potassium salts are easy to prepare and crystallise nicely because of low solubility at O C.
[Edited on 15-3-2015 by blogfast25]
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sparkgap
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I'd consider cyclopentadiene and acetylacetone to be acids, myself.
sparky (~_~)
"What's UTFSE? I keep hearing about it, but I can't be arsed to search for the answer..."
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woelen
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An acid, which can be made and isolated fairly easily by an amateur is H4Fe(CN)6. This is a moderately strong acid (for the release of the first
H-atom).
But, despite all the examples, given in this thread, oxoacids are by far the most common ones. Nearly every element, capable of forming acids, allows
formation of oxoacids. Next, after oxoacids, are the fluoroacids. Fluoroacids are less numerous, because they require more fluorine atoms to be bonded
to the central element, but there are quite a few acids, some of them quite stable even in aqueous solution:
HBF4 (stable in aqueous solution, colorless, can be purchased as 40% solution in water)
HPF6
HSb6
H2TiF6 (stable in aqueous solution, colorless)
H3TiF6 (stable in aqueous solution, forms deep green solutions)
There are also mixed oxo-fluoro acids, with OH-groups replaced by F.:
HO-SO2F --> derived from SO2(OH)2
(HO)2-POF --> derived from PO(OH)3
(HO)2-TeF4 --> derived from Te(OH)6
(HO)4-TeF2 --> derived from Te(OH)6
There probably are more.
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Quieraña
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There is a compound list to make of noble gas acids. Hydrogen helide is supposedly the most powerful acid out there, eating any container its in and
possibly only contained in ion state within a magnetic field.
I am curious about the chalcogen compounds, though. Bravo for putting it there. Maybe we can make a gang of pnictochalcohalogenic acids with nuclear
salts to boot.
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Σldritch
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Apparently AuF5 is a stronger fluoride acceptor than SbF5 so there's an acid for you. Don't actually know the properties of
AuF6-1. Never really heard about it but doesn't seem too unstable. Closed shell and all. Maybe it is really oxidizing even as a
salt or perhaps you could make the anion by dismuting Gold Chlorides with flouride salts. The only paper I found treating the acid computationally
models its formation by protonation of the anions.
EDIT: H2(B12(OH)12) is worth mentioning too as a little known mineral oxyacid. It is quite strong. It also has the
interesting property that its Hydronium salt (H3O)2B12(OH)12 is insoluble in water(!) and an excellent
proton conductor.
[Edited on 1-1-2023 by Σldritch]
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DraconicAcid
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There's also bis(triflyl)imine CF3SO2NHSO2CF3 and related acids.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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clearly_not_atara
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The reason that practically all of the covalent acids are oxoacids is that the other elements would be oxidized or they are monovalent (F, Cl, Br); in
the latter case there are no variations. There are a few acidic thiols, e.g. HSCN, F5C6SH, but they have a tendency to decompose. There are also the
imides, e.g. Tf2NH, and carborane acid, which is sterically hindered and relies on that weird delocalized boron-bonding, and there are the ionic
acids, e.g. HAlCl4, which are practically never isolable, existing only in solution.
| Quote: | Gold(V) fluoride is the inorganic compound with the formula Au2F10. This fluoride compound features gold in its highest known oxidation state. This
red solid dissolves in hydrogen fluoride but these solutions decompose, liberating fluorine.
[...]
Gold(V) fluoride can be synthesized by heating gold metal in an atmosphere of oxygen and fluorine to 370 °C at 8 atmospheres to form dioxygenyl
hexafluoroaurate |
Sounds like a breeze. New synthesis challenge? 
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Mateo_swe
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Honey, have you seen my wedding ring?
Sorry babe, had to use it for the new synthesis challenge but, hmm... it didnt turn out so well.
Neither will this... SMACK...
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Σldritch
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Thought of another (class of) unusual acid: F-1@C20F20
Also, speaking of HN(SO2CF3)2, has anyone heard of the acid HN(ClO3)2? With perchlorylamide
having been made surely someone has isolated salts of the latter acid. I've looked around but haven't been able to find anything. Perhaps because I've
got the name wrong. Anyone heard of it?
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chornedsnorkack
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What qualifies a "fluoroacid" as "existing"? What qualifies it as being an "acid"?
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Bedlasky
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Depending on how you define acid - as an electron pair acceptor (Lewis) or H+ donor (Brönsted acid). Any Brönsted acid is also Lewis acid, but not
every Lewis acid is Brönsted acid (for example AlCl3).
Fluoroacid is usually use as term for inorganic acid where OH group is replaced by F or for carboxylic acids with one or more F atoms on carbon
skeleton. I am not sure what do you mean what qualifies fluoroacid as existing? Practically any method of structural analysis.
There are also fluoroacids which are classified as fluoro complexes (HBF4, HPF6 etc.). I don't know that any acid of this type can be isolated in a
pure state (someone correct me if I wasn't right), salts if these acids are known. These acids surely exist in the solution - for example SbF5
dissolve in anhydrous HF to form mostly [Sb2F11]- and H2F+ ions. H2F+ are pretty acidic, so you can call this acid even in classical Brönsted
definition.
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chornedsnorkack
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Quote: Originally posted by Bedlasky  |
Fluoroacid is usually use as term for inorganic acid where OH group is replaced by F or for carboxylic acids with one or more F atoms on carbon
skeleton. I am not sure what do you mean what qualifies fluoroacid as existing? Practically any method of structural analysis.
There are also fluoroacids which are classified as fluoro complexes (HBF4, HPF6 etc.). I don't know that any acid of this type can be isolated in a
pure state (someone correct me if I wasn't right), salts if these acids are known. These acids surely exist in the solution - for example SbF5
dissolve in anhydrous HF to form mostly [Sb2F11]- and H2F+ ions. H2F+ are pretty acidic, so you can call this acid even in classical Brönsted
definition. |
Compare NH4OH. Can you isolate ammonium hydroxide in a pure state?
It is easy to produce a liquid with the exact composition of NH4OH. The solubility of 1 bar ammonia in water increases rapidly with falling
temperature, from 31% at 25 C or so to 47% at 0 C.
Cool water just a bit under 0 C under 1 bar NH3 and you will get exactly 48,5% ammonia. Which is pure liquid NH4OH.
It is also easy to get NH4OH in solid form. When you freeze ammonia solution, NH4OH is one of the freezing point maxima, pure crystals freezing around
-80 C.
But by structural analysis, is either 48,5% ammonia solution or its frozen form behaving as NH4OH, or more like molecular NH3.H2O?
Liquid HF has a surprisingly small surface tension. Quoted as 10,2 mN/m at 0 C. Compare pentane, which is around 18 mN/m. How good solvent is liquid
HF for molecular solutes which are actually poorly ionized there? HF freezes at -85 C. SiF4 boils at -90 C. Does boiling SiF4 dissolve HF well?
Note that concentrated HF is actually a very strong acid compared to dilute HF and many other acids.
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