Ammonium halides hydroxide

Ammonium halides, 2 714-715 vapor pressure, 2 715t Ammonium hydrosulfide, 2 728 Ammonium hydroxide, for fermentation, 11 38... 

Because of their high lipophobic character, compared with other ammonium salts, quaternary ammonium hydroxides are not readily prepared by liquidrliquid anion exchange. Only with quaternary ammonium hydrogen sulphates is it possible to transfer the ammonium hydroxide into the organic phase in any viable degree of concentration [30] and this procedure remains the cheapest and simplest procedure. Other methods include treatment of quaternary ammonium halides with silver oxide [31] and by anion exchange using polymer bound hydroxide [e.g. 32]. 

The use of mixtures of sodium hydroxide and benzyltrimethylammonium chloride or tetrabutylammonium bromide failed to enhance the DPGE alkylation of HEC by the in situ formation of the corresponding quaternary ammonium hydroxide phase transfer catalyst. These quaternary ammonium halides are too soluble in aqueous /-butyl alcohol and are preferentially extracted into the organic phase. Mixtures of benzyltrimethylammonium hydroxide and sodium acetate were also ineffective in enhancing the DPGE alkylation of HEC for the same reason, namely preferential solubility of benzyltrimethylammonium acetate in the organic phase. 

It is reported that trimethylamine in combination occurs in large amounts in beet-root residues 2 and can be obtained from them by the action of caustic soda it occurs also in herring brine.3 From both of these sources, however, the substance is obtained in an impure state and can be purified only by rather tedious methods. This is indicated by the fact that trimethylamine has always been an expensive substance. Synthetic methods for its production are by the action of methyl iodide on ammonia 4 by the distillation of tetramethylammo-nium hydroxide 6 by the action of magnesium nitride upon methyl alcohol 6 by the action of zinc upon trimethyloxy-ammonium halides 7 by the action of formaldehyde upon ammonium chloride under pressure 8 by the action of ammonium chloride upon paraformaldehyde.9 Of these syn-... 

Tertiary amines do not react with nitrous acid, acetyl chloride, benzoyl chloride, benzenesulfonyl chloride, but react with alkyl halides to form quaternary ammonium halides, which are converted by silver hydroxide to quaternary ammonium hydroxides. Quaternary ammonium hydroxides upon heating yield (1) tertiary amine pins alcohol (or, for higher members, olefin plus water). Tertiary amines may also be formed (2) by alkylation of secondary amines, e.g., by dimethyl sulfate, (3) from amino acids by living organisms, e g, decomposition of fish in the case of trimethylamine. 

Organotin halides can also be obtained from oxides or hydroxides on reaction with hydrogen halides (or ammonium halides) (equation 61) and from tin-tin bonded species on reaction with halogens (equation 62). 

When a solution of a quaternary ammonium halide is treated with silver oxide, silver halide precipitates. When the mixture is filtered and the filtrate is evaporated to dryness, there is obtained a solid which is free of halogen. An aqueous solution of this substance is strongly alkaline, and is comparable to a solution of sodium hydroxide or potassium hydroxide. A compound of this sort is called a quaternary ammonium hydroxide. It has the structure R4N OH. Its aqueous solution is basic for the same reason that solutions of sodium or potassium hydroxide are basic the solution contains hydroxide ions. 

In this reaction two different procedures have been used. The first is the classical Hofmann degradation, which prepares the alkene by thermal decomposition of the quaternary ammonium hydroxide. Hofmann orientation is generally observed in acyclic and Zaitsev orientation in cyclohexyl substrates. The second is the treatment of quaternary ammonium halides with very strong bases, e.g. PhLi, KNH2 in liquid NH3. The formation of the alkene proceeds via an 1 mechanism, which means a syn elimination in contrast to the anti elimination which is observed in most of the classical Hofmann degradations. In some cases this type of elimination can also be accomplished by heating the salt with KOH in polyethylene glycol monomethyl ether. 

In processes of producing alkylamines, and particularly methyl-amines, by reacting the corresponding alkyl chlorides, halides, hydroxides and so forth, with ammonia or ammonium salts such as ammonium chloride, the reaction product usually contains substantial quantities of all three of the primary, secondary and tertiary amines, even though the temperature, pressure, proportions and other reaction conditions may be controlled so as to give rise to a preponderance of one of said amines. 

For a quaternary ammonium ion to undergo an elimination reaction, the counterion must be hydroxide ion because a strong base is needed to start the reaction by removing a proton from a j8-carbon. Since halide ions are weak bases, quaternary ammonium halides cannot undergo a Hofmann elimination reaction. However, a quaternary ammonium halide can be converted into a quaternary ammonium hydroxide by treating it with silver oxide and water. The silver halide precipitates, and the halide ion is replaced by hydroxide ion. The compound can now undergo an elimination reaction. 

The ambident zwitterion-carbene intermediate can react with nucleophiles to give products originating from both a and y attack. Hydroxide and ethoxide ions prefer the propargyl to the allenyl position exclusively, while azide prefers it by a factor of 8, thiophenoxide by a factor of 1.6, and bromide attacks the two positions almost equally . The reaction with trimethylamine produces quaternary ammonium halides these have propargylic structure when R = R = CHg or -(CHafs-. When R and R are larger than CH3 the products are allenic. Diethyl sodiomethylmalonate affords propargylic and allenic products in the ratio of 2.6 1 (ref. 59). Under aprotic conditions the zwitterion-carbene adds on to olefins with formation of alkenylidencyclopropanes " (cf. p. 407). 

A modified interfacial mechanism has been proposed by Starks [1] assuming that tetraalkylammonium hydroxide, generated at the interphase by ion exchange between ammonium halide and sodium hydroxide, acts as a base for substrate deprotonation. This mechanism has been disputed by Mqkosza through competitive addition of CCl3 anions to A-alkylpyridinium salts and carbanion acceptors such as vinyl acetate [31]. 

Quaternary ammonium hydroxides (4,267-268). The use of an anion-exchange resin for conversion of quaternary ammonium halides into the hydroxide has been published. The method is suitable for even very sensitive compounds and is superior to silver oxide (expensive) or thallous ethoxide (expensive and toxic). 

In the two-phase alkylation using alkali hydroxides as bases and quaternary ammonium halides as catalysts (20) a reverse order (RCl > RBr > RI) of the customary alkylator reactivity prevails. Quaternary ammonium iodides exhibit little catalytic effect (21). Because the effective concentration of R4N Nu is low and limited by the initial amount of catalyst, the nucleophile cannot be expected to compete successfully for the alkylating agent with I , if its softness lies in between OH and I . 

Quaternary ammonium halides—because they do not have an unshared electron pair on the nitrogen atom—cannot act as bases. Quaternary ammonium hydroxides, however, are strong bases. As solids, or in solution, they consist entirely of quaternary ammonium cations (R4N ) and hydroxide ions (HO ) they are, therefore, strong bases—as strong as sodium or potassium hydroxide. Quaternary ammonium hydroxides react with acids to form quaternary ammonium salts ... 

Quaternary ammonium hydroxides can be prepared from quaternary ammonium halides in aqueous solution through the use of silver oxide or an ion exchange resin ... 

When a quaternary ammonium halide is treated with moist silver(I) oxide (a slurry of AgjO in H2O), silver halide precipitates, leaving a solution of a quaternary ammonium hydroxide. 

Reaction of a quaternary ammonium halide with moist silver oxide to produce a quaternary ammonium hydroxide followed by heating to give an alkene is a reaction known as the Hofmaim elimination. 

While a number of different phase transfer catalysts such as tetrabutyl ammonium halides (Ref. 10, 11), tetrabutyl ammonium hydroxide (Ref. 16-18), tetrabutyl ammonium hydrogen sulfate (Ref. 21-22), Adogen-464 (Ref. 16, 18), tetrabutyl phosphonium bromide (Ref. 19, 20), 18-crown-6 (Ref. 12, 13, 19, 20), cryptand [222] (Ref. 21, 22), etc., have been used in the chemical modification of polymers, few systematic studies of the influence of the catalyst on the reactions have been done. It is presumed that the same considerations which govern the choice of a phase transfer catalyst for classical organic synthesis also apply in the case of reactions with polymers. 

The use of an extractor-type polymeric catalytic membrane reactor has also been described by Wu et for phenol allylation. Ion-exchange membranes, consisting of poly (styrene quaternary ammonium halide) cross-linked with divinylbenzene paste on polypropylene non-woven fabric, were assembled in a two-chamber flat membrane reactor, either in a horizontal configuration or in a vertical configuration. One of the chambers was filled with an aqueous solution of phenol and sodium hydroxide, while the other chamber was filled with a solution of allylbromide in dichloroethane, the membranes acting as phase transfer catalysts according to the mechanism depicted in Fig. 1.5. 

C) Phenacyl and p-Bromophenacyl esters. Ammonium salts in aqueous-ethanolic solution do not however usually condense satisfactorily with phenacyl and />-bromophenacyl bromide. The aqueous solution of the ammonium salt should therefore be boiled with a slight excess of sodium hydroxide to remove ammonia, and the solution then cooled, treated with hydrochloric acid until just alkaline to phenol-phthalein, and then evaporated to dryness. The sodium salt is then treated as described (p. 349) to give the ester. Filter the ester, and wash with water to remove senium halide before recrystallisation. 

The halide anion of quaternary ammonium iodides may be replaced by hydroxide by treatment with an aqueous slurry of silver oxide Silver iodide precipitates and a solu tion of the quaternary ammonium hydroxide is formed... 

Methylsuccinic acid has been prepared by the pyrolysis of tartaric acid from 1,2-dibromopropane or allyl halides by the action of potassium cyanide followed by hydrolysis by reduction of itaconic, citraconic, and mesaconic acids by hydrolysis of ketovalerolactonecarboxylic acid by decarboxylation of 1,1,2-propane tricarboxylic acid by oxidation of /3-methylcyclo-hexanone by fusion of gamboge with alkali by hydrog. nation and condensation of sodium lactate over nickel oxide from acetoacetic ester by successive alkylation with a methyl halide and a monohaloacetic ester by hydrolysis of oi-methyl-o -oxalosuccinic ester or a-methyl-a -acetosuccinic ester by action of hot, concentrated potassium hydroxide upon methyl-succinaldehyde dioxime from the ammonium salt of a-methyl-butyric acid by oxidation with. hydrogen peroxide from /9-methyllevulinic acid by oxidation with dilute nitric acid or hypobromite from /J-methyladipic acid and from the decomposition products of glyceric acid and pyruvic acid. The method described above is a modification of that of Higginbotham and Lapworth. ... 

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