Liquid NH3 treatment

Liquid NH3 Treatment. Transverse cross sections of air-dry, 20-mil microtomed sugar maple were immersed in liquid NH3 at 30 °C. (ca. 150 p.s.i.). The samples were washed with fresh liquid NH3, air-dried, and water-washed for several days. 

Later a modified procedure for the preparation of 3,6-bis(trifluoromethyl) phthalodinitrile 83b was elaborated [67] (Scheme 23), which starts from 2,5-bis(trifluoromethyl)benzoyl chloride 86 and includes its conversion to N,N-diethylamide 87, carboxylation of the latter in the presence of 2,2,6,6-tetramethylpiperidine, followed by direct formation of the imide 81b ( 59 % overall yield). The diamide 82b obtained with liquid NH3 treatment (28 % yield), was then converted to dinitrile 83b with triflic anhydride in dioxane (yield... 

Nitroquinoxaline (71, Q = R = H) gave a separable mixture of 6-nitro-2-quinoxalinamine (71, Q = NH2, R = H) and 6-nitro-5-quinoxalinamine (71, Q = H, R = NH2) (liquid NH3, KMnOa, 5 h 51% and 32%, respectively) similar treatment of 2,3-dimethyl-6-nitroquinoxaline gave only 2,3-dimethyl-6-nitro-5-quinoxalinamine (18%) and unchanged substrate (55%) and other such aminations are also reported. ... 

Begin not with the ketone itself, but with an a,P-unsaturated ketone in which the double bond is present on the side where alkylation is desired. Upon treatment with lithium in liquid NH3, such a ketone is reduced to an enolate... 

The binuclear species (69) and (70) are prepared from the reaction of [Ir(PEt3)2(C2H4)2Cl] with liquid NH3, followed by treatment with NaBPh4 or pyridine, respectively. Both structures are determined by X-ray crystallography and show Ir—Ir distances of 3.33 A and 3.34 A, respectively.94... 

Thioethers (sulfides) can be prepared by treatment of alkyl halides with salts of thiols (thiolate ions).7S2 R may be alkyl or aryl. As in 0-35, RX cannot be a tertiary halide, and sulfuric and sulfonic esters can be used instead of halides. As in the Williamson reaction (0-12), yields are improved by phase-transfer catalysis.753 Instead of RS ions, thiols themselves can be used, if the reaction is run in benzene in the presence of DBU (p. 1023).754 Neopentyl bromide was converted to Me3CCH2SPh in good yield by treatment with PhS in liquid NH3 at -33°C under the influence of light.755 This probably takes place by an SrnI mechanism (see p. 648). Vinylic sulfides can be prepared by treating vinylic bromides with PhS in the presence of a nickel complex,756 and with R3SnPh in the presence of Pd(PPh3)4.757 R can be tertiary if an alcohol is the substrate, e.g,758... 

These rather simple considerations explain most of our experimental results—for example, the behavior of thermally treated samples, the different influences of dry and wet disintegration on acid and enzymatic hydrolysis, or the pronounced increase in accessibility to acid hydrolysis as compared to enzymatic degradation by treatment with liquid NH3. No definite interpretation can be given so far of the unexpected strong increase in weight loss during enzymatic degradation after a previous mercerization. 

The most interesting possibility consists of separation of the natural mixture of ni-trobenzenes containing 14N and 15N isotopomers (G.R. Stevenson, Lovett, Reiter 1986). A solution of 0.03 mmol of Ph15N02 and 0.08 mmol of PhN02 were treated with 0.01 mmol of potassium metal in dehydrated liquid NH3. After the evaporation of NH3, the mixture of the initial compounds with their anion radical potassium salts remains for further treatment. The neutral nitrobenzenes are liquid they are distilled out under high vacuum. The rest is solids. The solid remainder is oxidized with the solution of iodine in ether ... 

Fischer and Jira (95) treated [Ni(NH3)g](SCN)2 with CsHgK. in liquid NH3 to obtain [NKNHalaKCsHs) We obtained the same ionic complex directly from Ni(Tj5-C5H5)2 in liquid NH3 (96). We were also able to show similar behavior for Re(CO)sX (X = Cl, Br, I) which, on treatment with liquid NH3 at 60 or 120°C for at least 40 h, gives the ionic complexes cis-[Re(CO)4(NH3)2]X or [Re(CO)3(NH3)s]X (97). We similarly obtained an ionic pentacarbonylammine complex from Re(CO)5Cl and KSCN in liquid NH3 (97) ... 

To complete this treatment of the manifold types of reactions of the paramagnetic chromium complexes Cr(CO)jI and Cr2(CO)10I (cf. Section II1,D), it remains to discuss their behavior toward liquid NH3 (80). With CrfCOlgl, substitution of three CO ligands by NH3and addition of another NH3 molecule gives /rans-[Cr(CO)2(NH3)JI, which constitutes the first preparation of a cationic CO complex of chromium ... 

Treatment of the readily accessible compounds R2NCH2C3CCH2OR and RSCH2C C--CH2SR with r-BuOK in THF or liquid NH3 (in the case of the bis-thioethers) affords enyne amines R2NOCCH=CH2 [145] and the analogous sulfides RSC=CCH=CH2 [146] in good to excellent yields. The schemes below represent the two possible reaction paths (analogous... 

The range of Na weight percents in NH3 used was 1.27-3.3% in these examples. aTreatment temperature in liquid NH3 32°C. b Treatment temperature in liquid NH3 20°C. 

Treatment temperature in liquid NH3 -33°C. d Treatment temperature in liquid NH3 -33 °C. 

Reduction of 5-methyl-l-oxo-2,3,4,6,7,8-hexahydro-l//-pyrido[l,2-ajpyrazinium iodide, its 2-benzyl derivative and cis- and trans-5-methylperhydropyrido[l,2-a]pyrazin-l-ones with Li in liquid NH3 gave 1-methyldecahydro-l,5-diazecin-5-one (73CPB1248). Under the same conditions, 2-benzoyl-5-methylperhydro-pyrido[l,2-a]pyrazinium iodide afforded 2-benzylperhydropyrido[l,2-a]pyrazine. The 10-membered l-methyldecahydro-l,5-diazecin-5-one was also obtained from trans-5-methylperhydropyrido[l,2-fl]pyrazin-l-one by treatment with sodium amalgam in aqueous EtOH. 

Inclusion of bismuth atoms in heterocyclic ring complexes has been actively investigated for a number of years. Complexes of the type (17), for example, l-phenyl-2,5-dimethylbismole, have been sought for comparison with pyrrole derivatives and for information about the degree of aromaticity in its heavier analogs. Compound (17) is prepared via the addition of 2(Z),5(Z)-dilithio-3,4-dimethylhexa-2,4-diene to PhBil2 in 28% yield. This heterocycle is converted to the dibismuthine in the standard fashion treatment of (17) with Na in liquid NH3 followed by addition of 1,2-dichloroethane. 

A similar substitution reaction occurs with other strong bases. Treatment of bromobcnzene with potassium amide (KNH2) in liquid NH3 solvent, for instance, gives aniline. Curiously, thougli, when bromobenzene labeled with radioactive C at the Cl position is used, the substitution product has equal amounts of the label at both Cl and C2, implying the presence of a syimnetri-cal reaction intermediate in which Cl and C2 are equivalent. 

Although the Birch reduction (alkali metals in liquid NH3) of the pyrrole ring is apparently unknown (c/. equation 8), the partial reduction of pyrroles to 2,5-dihydropyrroles using Zn/HCl has been of considerable utility. For example, pyrrole gives 2,5-dihydropynole as the major product upon treatment with Zn dust/20% aq. HCl (equation 9), and Lemal and McGregor observed that 2,5-dimethylpyrrole gives a mixture of trans- (78%) and c/5-2,5-dimethyl-2,5-dihydropyrrole (22%) under similar conditions (47% yield). In one of these studies, Hudson and Robertson demonstrated that 2,5-dihydropyrrole is not reduced to pyrrolidine under these reaction conditions. Using these same conditions, Schumacher and Hall reported the reduction of 2-benzylpyrrole to the 2,5-dihydro derivative (67%) in a synthesis of the antibiotic anisomycin. ... 

Unactivated substrates also react with phenoxide ion with electrochemical catalysis in liquid NH3-Me2SO, to give diaryl ethers, presumably by the Sr I mechanism. Diaryl ethers can be prepared from activated aryl halides by treatment with a triaryl phosphate, (ArO)3PO. ... 

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. 

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