Sodium amide molecule

The most common conditions employed in the Madelung process are sodium/potassium alkoxide or sodium amide at elevated temperature (200-400 C). The Madelung reaction could be effected at lower temperature when -BuLi or LDA are employed as bases/ The useful scope of the synthesis is, therefore, limited to molecules which can survive strongly basic conditions. The process has been successfully applied to indoles bearing alkyl substituents. ... 

Of the several syntheses available for the phenothiazine ring system, perhaps the simplest is the sulfuration reaction. This consists of treating the corresponding diphenylamine with a mixture of sulfur and iodine to afford directly the desired heterocycle. Since the proton on the nitrogen of the resultant molecule is but weakly acidic, strong bases are required to form the corresponding anion in order to carry out subsequent alkylation reactions. In practice such diverse bases as ethylmagnesium bromide, sodium amide, and sodium hydride have all been used. Alkylation with (chloroethyl)diethylamine affords diethazine (1), a compound that exhibits both antihista-minic and antiParkinsonian activity. Substitution of w-(2-chloroethyl)pyrrolidine in this sequence leads to pyrathiazine (2), an antihistamine of moderate potency. 

As far as propargyl thioethers are concerned, the substrates in this section follow all the principles discussed for propargyl ethers and propargylamines in the two preceding sections. For alkyl propargyl thioethers typical bases used are sodium amide in liquid ammonia, alcoholate or alkali metal hydroxide [178, 186-189, 191, 287-291], and again some derivatives of carbohydrates have been used successfully [292, 293], If an ester group is also present in the molecule, the reaction can be accompanied by a hydrolysis to the carboxylate [294]. 

Reactions (9a) and (9b) proceed concurrently nitrous oxide first reacts with molten sodium amide to form sodium azide and water vapour. The latter then reacts with another molecule of sodium azide, hydrolysing it with the formation of sodium hydroxide and ammonium (9b). 

It is desirable to discuss more thoroughly polymerizations taking place in liquid ammonia-alkali metal or alkali amide systems. In the course of their investigation of styrene polymerization carried out in liquid ammonia and initiated by sodium amide, Sanderson and Hauser (14) found a constant molecular weight of about 3,000 for the resulting polymer. Its value was unaffected by the concentration of sodium amide, and it was not changed appreciably by the extent of polymerization. This was interpreted by the above workers as evidence for the termination due to a proton transfer from an ammonia molecule to a growing chain, i.e. 

Enolate ions formed from, ketones or aldehydes are extremely important in the synthesis of more complex organic molecules. The ease with which an enolate ion is formed is related to the acidity of the a proton. The pKa of propane (acetone) is 19.3 that means that it is a stronger acid compared to ethane (pKa 60) and a much weaker acid than acetic acid (pKa 4.7), i.e. strong bases like sodium hydride, sodium amide, and lithium diisopropylamide LiN(i-C3H7)2 are needed to form an enolate ion. 

Alkynes can be prepared from dihaloalkanes by elimination of two molecules of HX. This reaction requires very strongly basic conditions so potassium hydroxide at elevated temperatures or the stronger base sodium amide (NaNH2) is commonly employed. Examples are provided by the following equations ... 

Addition polymerization can also occur by a mechanism involving anionic intermediates. For example, styrene can be polymerized by the addition of a small amount of sodium amide. In this case the amide anion adds to the double bond to produce a carbanion. This carbanion then adds to another styrene molecule to form a larger carb-anion, and the process continues to form polystyrene ... 

For example, if we wanted to deprotonate ethyne (acetylene, piC, 25), then hydroxide (the strongest base we could have in aqueous solution, pJTa 15.7) would establish an equilibrium where only 1 in 109 3 (1015 7/1025) ethyne molecules were deprotonated. This means about 1 in 2 billion of our ethyne molecules will be deprotonated at any one time. Since, no matter what base we dissolve in water, we will only at best get hydroxide ions, this is the best we could do in water. So, in order to deprotonate ethyne to any appreciable extent, we must use a different solvent that does not have a p. Ca less than 25. Conditions often used to do this reaction are sodium amide (NaNH2) in liquid ammonia. 

This process is very slow unless a small amount of sodium amide, NaNH2, is added to catalyze the reaction. It is believed that the NH2- ion replaces Cl- from Cr3+ more rapidly because it is a stronger nucleophile. After it has become coordinated, the NH2 can abstract H+ from a solvent molecule to regenerate NH2 ... 

It is well known that the addition of ammonia or amines to nitriles leads to formation of various amidines 32 this type of oligomerization can be applied to the synthesis of heterocycles. On heating in the presence of sodium amide (or benzenesulfonic acid in some cases), o-cyanoaniline produces a mixture of the quinazoline (18) by dimerization and the tricycloquinazoline (19) by trimerization the trimer is obtained when the dimer is heated with another molecule of the monomer and sodium amide at 300°. The mechanism of this condensation has been reviewed.33... 

Water reacts with a second molecule of sodium amide to form sodium hydroxide and ammonia. 

The chemistry of alkali amides was well investigated in the early twentieth century [3, 4], especially, sodium amide (NaNH2) has been used as a reagent in synthetic organic chemistry because of its ability to promote condensation reactions, to introduce amino groups into a molecule, and to remove the elements of water or of a hydrohalide acid. Lithium nitride has also been investigated for more than 50 years [5]. 

In the reaction with triphenylmethyl sodium the molecule of H3N3S2 certainly remains intact, since the isolation of the monosodium salt would otherwise be difficult to understand. It is still uncertain whether, in the reaction with potassium amide, the molecule is decomposed or remains intact that is, whether the potassium salt has the formula (XXIX) or (XXX) and (XXXI). 

Propyne can be prepared by introducing a triple bond by eliminating two molecules of hydrogen bromide. The de-hydrohalogenation proceeds in two steps. Sodium amide... 

Alkynes can be formed from 1,2-dibromoalkanes (or vicinal dihalides) by elimination of two molecules of HX using a strong base (e.g. sodium amide, NaNHa). 

The interaction of 64a with sodium amide in liquid ammonia gives dinitroxide 51, and the interaction of 64b with 1,5-diazabicyclo- [5,4,0] undecene-5 (DBU) in THF yields 4-vinyl-3-imidazoline-3-oxide-l-oxyl (73). This vinyl nitroxide (73) easily adds a molecule of bromine, giving dibromo derivative 74, and it regenerates 6b on treatment with NaBH4. Dehydrobromination of 75 under similar conditions leads to nitroxide 76 (Grigor ev et al, 1979a). 

Now let s draw the forward scheme. The starting material, -l,ll-dibromo-l-undecene, is treated with sodium acetylide to produce a terminal alkyne. Deprotonation with sodium amide, followed by treatment with a second equivalent of -l,ll-dibromo-l-undecene gives the internal alkyne. Reduction of the alkyne with H2 and Lindlar s catalyst affords the cis alkene. Further treatment with two equivalents of magnesium yields the bis-vinyl Grignard, which reacts with two equivalents of the aldehyde. Aqueous workup produces the target molecule, duryne. 

The traditional method for transforming carboxylic acids into reactive acylating agents capable of converting alcohols to esters or amines to amides is by formation of the acyl chloride. Molecules devoid of acid-sensitive functional groups can be converted to acyl chlorides with thionyl chloride or phosphorus pentachloride. When milder conditions are necessary, the reaction of the acid or its sodium salt with oxalyl chloride provides the acyl chloride. When a salt is used, the reaction solution remains essentially neutral. 

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