Oxirane reactions with ammonia

Reaction of Lithium AlkynyGdes with Oxirane m Liquid Ammonia... 

Ethylene oxides (oxiranes) react exothermally at room temperature with ammonia and most strongly basic amines presence of water or an alcohol accelerates the reaction. N.B. There is danger of explosions when working with oxirane. 

Ammonia and oxirane itself give various proportions of mono-, di-, and tri-ethanolamine according to the proportions of the reactants used the products can be separated by distillation.1108 Reaction with primary or, more so, secondary amines is more clear-cut. 2-(Diethylamino)ethanol is best obtained in this way ... 

Reaction of Bis(methylthio)methane with Potassium Amide in Liquid Ammonia and Subsequent Reaction with Oxirane... 

The conditions described in this experiment are typical for hydroxyalkylation of anionic species with oxirane in liquid ammonia. The reaction with sp3 -anions in this solvent is very fast, except in the case of enolates. Yield of the /J-hydroxyalkyl derivatives are good, provided the anionic species is present in a sufficiently high equilibrium concentration. This is probably not the case when lithium amide is... 

It should be noted that in spite of some difference in transition states geometries, all used approached give close values of In contrast to reaction with HF the alternative reaction with front-side approach of ammonia molecule to oxirane energetically is less favorable (E =200.7 kJ/mol (B3LYP/6-31G(d) [51])). 

Table 10.5 Calculated activation energy (E ) for the reaction of oxirane (1) and complexes (SOSO) with ammonia (in kJ/mol)...

So far, no reference has been made to the presence of more than one phase in the reactor. Many important chemicals are manufactured by processes in which gases react on the surface of solid catalysts. Examples include ammonia synthesis, the oxidation of sulphur dioxide to sulphur trioxide, the oxidation of naphthalene to phthalic anhydride and the manufacture of methanol from carbon monoxide and hydrogen. These reactions, and many others, are carried out in tubular reactors containing a fixed bed of catalyst which may be either a single deep bed or a number of parallel tubes packed with catalyst pellets. The latter arrangement is used, for exjimple, in the oxidation of ethene to oxiran (ethylene oxide)... 

In the case of slow reactions it is inconvenient trying to maintain a sufficiently low temperature throughout the conversion in a normal flask, even with the use of a dry icc-aceione condenser. It is much easier to allow the reaction to proceed in a round- bottomed Dewar flask (fig. 7, a flask with an evacuated space between the two walls). The rate of evaporation is reduced to a minimum (10 g/h or less) if the inner wall is covered with a silver mirror (covering the flask with aluminum foil is a good alternative). An example of a reaction in a Dewar flask is the conversion of Li CH with oxirane to HOCCf CI OLi (Chap, m, exp. 23). The ammoniacal soludon of LiCeCH is first prepared in the usual apparatus and then transferred (by pouring) into the Dewar flask. The oxirane is subsequently added over a short period and a stopper with a drying tube is placed on the flask. After 24 b the soludon is poured into a normal round-bottomed flask and the ammonia is removed by evaporanon. 

All acetylenes with a terminal triple bond are instantaneously converted into the alkali acetylides by alkali amides in liquid ammonia. For many alkylations with primary alkyl halides liquid ammonia is the solvent of choice and the functionalization with oxirane can also be carried out in it with good results. Reactions of ROOM with sulfenyladng agents (R SSR1, R SON, R SSC R ) or elemental sulfur, selenium or tellurium are mostly very successful in ammonia, the same holds for the preparation of ROC1 from RC=CM and iodine. The results of couplings with carbonyl compounds are very variable. 

Although the reaction of alkali acetylides with oxirane proceeds slowly in liquid ammonia 15], it is an excellent method for preparing "homo-propargylic alcohols in quantities of 1 mol or more [2). Since oxirane is very volatile, considerable losses could occur if it is allowed to be swept along with the escaping ammonia vapour. One solution is to carry out the reaction under reflux, using a special condenser filled with dry ice and acetone. This would require regular addition of dry ice over a period of at least 12 h. It is much simpler to mix the acetylide... 

In the procedures described below, lithium alkynylides are used. When R is CH3 or higher alkyl, the use of this cation is clearly preferred for several reasons. In particular the sodium alkynylides are poorly soluble in liquid ammonia. The second reason for choosing the lithium compounds is that the reaction of NaOCH with (an excess of) oxirane affords appreciable amounts of the subsequent product HOCCH2CH2OCH2CH2OH. 

Birch reduction using sodium155 507 or lithium508 in liquid ammonia removes BOM ethers in good yield. In the example shown in Scheme 4.277,467 a BOM ether and a benzyl ether were cleaved simultaneously. Provided the temperature is kept low and the reaction time short, a BOM group can even be removed with Na in liquid ammonia in the presence of an oxirane 509 Lithium di-fe/7-butylbiphenylide (LiDBB) has also been used [Scheme 4,278],510... 

Ammonia and primary amines react with azirdines to give 1,2-diamines. The mechanism and the stereochemistry of this reaction are similar to the corresponding reactions of the oxiranes. 

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