Unstable salt

If tetramethylammonium chloride is dissolved in hydrochloric acid, the unstable salt [(CH3)4N] [HClj], can be crystallised out here chlorine is showing weak hydrogen bonding (cf. F H—F which is stable, and Cl - H—Cl which is unstable). 

Although the complex ion [MnClg] is unstable, salts such as K2[MnF6] (containing the octahedral hexafluoromanganate(IV) ion) are much more stable and can be crystallised from solution. 

Meconin, C10H10O4, was isolated from opium in 1832 by Dublanc, and also occurs in Hydrastis canadensis. It crystallises from water in prisms, m.p. 102°, and dissolves in alkaline solutions, forming unstable salts of meconinic acid, CioHjgOg, of which it is the lactone. It was-... 

A possible additional cause is the formation of a highly unstable salt, similar to fulminate, by the action of nital on metals. In order to prevent future incidents, it is recommended that methanol be used in lieu of ethanol in nital mixts (Ref 2) Refs 1) H.H. Fawcett, C EN 27, 1396 (1949) CA 43, 5593 (1949) 2) F. Fromm et al, C EN... 

It should be noted that calcium bicarbonate does not exist in the solid state rather, it exists as an unstable salt in water, provided that an excess of free carbon dioxide is available to maintain equilibrium. The reaction is shown below. 

With amines and in the presence of heavy metal oxides (Ag, Hg), 1-nitropropane forms very unstable salts. 

With DMSO and aliphatic sulphoxides, dry perchloric acid also forms very unstable salts. If the acid concentration is 70% or more, when it comes into contact with DMSO, this gives rise to an immediate explosion. Aromatic sulphoxides give rise to far less dangerous interactions. 

In the current era neutral compounds are important simply because there are so many of them especially in screening collections made in automated chemistry for HTS. Other things being equal, a compound with an ionizable moiety is preferred to a neutral compound. By definition a neutral compound will not give an acid or basic pJCj value. Some essentially neutral compounds can form aqueous unstable salts. This most commonly occurs when an extremely poorly basic compound is dissolved in organic solvent and the salt is precipitatated, e.g. by bubbling in HCl gas. 

Undoubtedly the most significant discovery in colour chemistry in the post-Mauveine period was due to the work of Peter Griess, which provided the foundation for the development of the chemistry of azo dyes and pigments. In 1858, Griess demonstrated that the treatment of an aromatic amine with nitrous acid gave rise to an unstable salt (a dia-zonium salt) which could be used to prepare highly coloured compounds. 

At this point the oxidation stage of quinonediimine has been fully reached its (very unstable) salts have scarcely any colour. The production of colour only takes place when quinonoid and benzenoid systems are present together. The molecular union of the two substances at different stages of oxidation produces the intense absorption which is a prerequisite for the formation of a dye (Willstatter and Piccard). This union need not take place in the proportion 1 1, which obtains in the present case. The relations between quinhydrone and quinone-quinol are quite similar (p. 314). 

Thioamides are converted into 5-benzyl salts under basic catalysed conditions. The unstable salts spontaneously eliminate benzylthiol to yield nitriles (>80%) [47] the benzylthiol is benzylated during the reaction and is isolated as dibenzyl sulphide. 

Recently, both enantiomers each of cis- and tran5 -5-butyl-2-heptylpyrrolidine (10c) have been synthesized from glutamic acid by an excellent method with high diastereomeric and enantiomeric purity (417). The thiolactam (293) prepared from L-glutamic acid was reacted with benzyl 2-(trifluoromethylsul-fonyloxy)oetanoate to yield the rather unstable salt (294), which without purification was treated with triphenylphosphine and A-methylpiperidine to afford... 

Diazonaphthalene or Naphthalenediazonium Hydroxide, C10H7N2OH, mw 172 18, N 16.27%. Exists in three modifications, all in the form of salts, some of which are expl (Ref 1) l(or alpha)-Diazonapbthalene [called l(or. a)-Diazonaphthalin or Naphthalin-diazonium-hydroxyd-(l) in Ger], Ci0Hy.N( N).OH forms the following unstable salts ... 

Dicblorophenol, hexagonal ndls (from benz), mp 43°, bp 2o6-08°at 753 mm press, vol with steam forms some unstable salts most important use is in the manuf of 2,4 D (2,4-dichlorophenoxyacetic acid), a powerful plant-growth regulator (Refs 2 6)... 

Dicyanamide (called Dicyanamid, Dicyanimid or Imino-dicarbonsaure-dinitril in Ger), NC.NH.CN mw 67,05, N 62.67% ndls + H20 obtd by reacting cbloramine with an aq soln of KCN and by other methods forms some unstable salts such as ... 

Nitro-N, N-diethylaniline, red-colored oil, fr p -37° forms some unstable salts, such as Hydrobromide, CiqHi4N202 + HBr, hygr lfts (from ale), dec 160° Hydrochloride, C1QH14N2O2 +HCI, prisms (from ale), dec 156° Hydroiodide, CjqH C + HI,... 

C. Marie and R. Marquis, and I. Bellucei and D. Venditori. W. Manchot and A. Waldmiiller obtained with palladium salts the complexes palladous dinitrosyl-chloride, PdCl2.2NO, and palladous dinitrosylsulphate, PdS04.2N0. They are unstable salts giving off nitric oxide in the presence of water. Nitric oxide with palladous nitrate yields Pd(N02)2. Hence, nitric oxide is known to form complexes with the salts of Cu, Mn, Fe, Co, Ni, and Pd. 

E. Fremy called this salt sulfazilate de potasse A. Claus, oxysulfazotins ure Kalium and T. Haga, potassium peroxylamwosulphonate. T. Haga said that the unstable salt should be prepared just when it is wanted, and recommended the following process ... 

It should be noted that calcium bicarbonate does not exist in the solid state, but rather it exists as an unstable salt in water, provided that an excess of free carbon dioxide is available to maintain equilibrium. Loss of free carbon dioxide in the recirculating cooling water, due to either a rise in temperature (as occurs in a heat exchanger) or an increase in pH (say due to an increase in cycles of concentration), leads to a change of equilibrium and the resultant rapid and troublesome precipitation of insoluble calcium carbonate. 

Primary amines react with nitrous add to form diarxifiiitm salts. Aliphatic (nonaromatic) amines form extremely unstable salts that decompose spontaneously to form nitrogen gas. Aromatic amines also form unstable diazonium salts, but at temperatures bedow 5°C they decompose very slowly,... 

Several reaction intermediates can be observed by varying the reaction conditions. If equimolar amounts ofbromine and hydroxide are added to acetamide (26, R = Me, Scheme 2.11), the product is N -bromoacetamide (27, R = Me). Further reaction with base gives unstable salts (28), which rearrange to isocyanates (29) reaction with water and an excess of hydroxide finally leads to the amine product (30), but in alcoholic solutions urethanes (31) are formed. 

The hexasolvated compound was being prepared from a mixture of the hydrated salt, methanol and dimethyl sulfoxide but inexplicably mercury(I) oxide came out of solution. This was redissolved by addition of perchloric acid and the solution was refrigerated for 60 h. After addition of molecular sieve to remove the water present, the solution was filtered and the sieve treatment repeated four more times. During the final filtration, a violent explosion occurred in the funnel. The most likely cause was formation of methyl perchlorate promoted by the dehydrating action of the sieve, but dimethyl sulfoxide also forms an unstable salt with perchloric acid, so this also may have been involved [1], During preparation of... 

Amines and Heavy Metal Oxides. Contact with amines and mercury or silver oxide may lead to unstable salts analogous to nitromethane. 

Carbamates. Unstable salts formed between carbamates and PC15, which may decompose explosively.4... 

The ring-chain tautomerism of oxazolidines is discussed in Section 4.18.2.5.2. Oxazolidines form unstable salts which are easily hydrolyzed (equation 80) (77RRC1413). IV-Substituted oxazolidines react with enamines in the presence of trifluoroacetic acid to yield 1,4-oxazepines in a ring-opening 1,5-cycloaddition reaction (equation 8,1) (80LA1573). 

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