Deuterated methanol

With more strongly basic tertiary amines such as triethylamine, another mechanism can come into play. It has been found that wften methanol deuterated on oxygen reacts with acyl chlorides in the presence of triethylamine, some deuterium is found a to the carbonyl group in the ester... 

Another example of the separation of isotopomers was observed with deuterated benzoic acid, eluted with acidified 30% aqueous methanol. Deuteration, especially at meta and para positions, decreases retention.136 Ratios of retention times are presented in Table 9, where the IEs of monodeuterated benzoic acid or of benzoic-2,6-% acid are omitted because they are too small to produce resolvable peaks although they do lead to detectable peak broadening. Because the IEs are strongest at positions more distant from the carboxyl group, and because the elution conditions were sufficiently acidic that the benzoic acid was not ionized, an IE on the pKa was rejected as responsible. Instead some sort of lipophilic interaction was suggested, and deuteration at the ortho positions is less effective because the carboxyl group hinders those positions. However, it should be noted that the data in Tables 2 and 3 indicate that the IE on acidity does not fall off at meta and para positions.24,32... 

Pyridine is more nucleophilic than an alcohol toward the carbonyl center of an acid chloride. The product that results, an acylpyridinium ion, is, in turn, more reactive toward an alcohol than the original acid chloride. The conditions required for nucleophilic catalysis therefore exist, and acylation of the alcohol by acid chloride is faster in the presence of pyridine than in its absence. Among the evidence that supports this mechanism is spectroscopic observation of the acetylpyridinium ion." With more strongly basic tertiary aliphatic amines such as triethylamine, another mechanism also comes into play. It has been found that when methanol deuterated on oxygen reacts with acid chlorides in the presence of triethylamine, some deuterium is found a to the carbonyl group in the ester ... 

In theory two carbanions, (189) and (190), can be formed by deprotonation of 3,5-dimethylisoxazole with a strong base. On the basis of MINDO/2 calculations for these two carbanions, the heat of formation of (189) is calculated to be about 33 kJ moF smaller than that of (190), and the carbanion (189) is thermodynamically more stable than the carbanion (190). The calculation is supported by the deuterium exchange reaction of 3,5-dimethylisoxazole with sodium methoxide in deuterated methanol. The rate of deuterium exchange of the 5-methyl protons is about 280 times faster than that of the 3-methyl protons (AAF = 13.0 kJ moF at room temperature) and its activation energy is about 121 kJ moF These results indicate that the methyl groups of 3,5-dimethylisoxazole are much less reactive than the methyl group of 2-methylpyridine and 2-methylquinoline, whose activation energies under the same reaction conditions were reported to be 105 and 88 kJ moF respectively (79H(12)1343). 

Complete exchange of protons in a sterically unhindered position a to a carbonyl group can be achieved by heating a solution of the ketone in O-deuterated solvents in the presence of an acid or base catalyst, the latter being the more effective. The most commonly used solvents are methanol-OD, ethanol-OD, and the aprotic solvent anhydrous tetrahydrofuran or dioxane mixed with deuterium oxide. Under alkaline conditions the exchange rate in 153 2 14,164 stcroids, for example, is usually... 

Deuteration of 3 -Hydroxy-5a-androstan-7-one at C-6 and C-8 by Exchange with Deuterium Oxide-5% Sodium Deuterioxide in Methanol-OD... 

Deuteration of 5a.-Pregn-9-en-12-one at C-8 and C-11 by Exchange with Deuterium Oxide-20% Sodium Deuterioxide in Methanol- OD... 

There are ample precedents for reductions of double bonds in conjugated enones with lithium in deuterioammonia (see section V-C). Examples of the reduction of saturated ketones in deuterated media appear only as side reactions (over reductions) during the above mentioned conversions. For experimental details, therefore, one should consult the literature for the analogous reductions in protic medium (see also chapter 1). The use of deuterioammonia is essential for labeling purposes since by using liquid ammonia and methanol-OD the resulting alcohol contains no deuterium. For the preparation of deuterioammonia see section IX-D. 

Exchange with deuterium oxide-10% deu-teriosulfuric acid in methanol-OD deuteration of estradiol at C-2 and C-4, 157... 

For detritiation in deuterated methanol (containing a small amount of tritium). d For deuteration in deuterated methanol. 

High Pressure Study of the Methanol Reaction Using Deuterated Methanols... 

The isotopic method has been used in conjunction with a flow apparatus by Stranks, to measure the exchange between the cyclopentadienyl complexes of iron (III) and iron (II) in methanol. Separation was based on the insolubility of Fe(C5H5) in petroleum ether at —80 °C. Using Fe(II) and Fe(III) 10 M and short reaction times ( msec), a rate coefficient 8.7 x 10 l.mole .sec at — 75 °C was obtained. The rate of exchange in the presence of chloride ions and inert electrolytes was found to be more rapid. Calculations using Marcus Theory showed reasonable agreement with the experimental observations. In deuterated acetone, line broadening measurements have led to an estimate of this rate coefficient of > 10 l.mole . sec at 26 °C. 

D2O = deutered water. HPLC = high performance liquid chromatography. IS = internal standard. MeOH = methanol. MS = mass spectrometry. NMR = nuclear magnetic resonance. PDA = photodiode array detector. TEA = triethylamine. MTBE = methyl tert-butyl ether. 

Combine a 0.5-mL aliquot of the Anal sample exAact or a 0.020 igmL azinphos-methyl standard solution in acetone-water (2 1 v/v) with 0.5 mL of a 0.040 ig mL deuterated internal standard solution in methanol-water (2 3 v/v) in an HPLC autosampler vial. Combination may be made using other volumes as long as the solutions are combined 1 1 (v/v). Inject 200 aL from the 0.020 and 0.040 igmL standard/internal standard soluAon. Inject 200 aL from each of the 10 sample exAact/ internal standard soluAons. Inject 200 p-L from anoAier 0.020 and 0.040 pgmL standard/internal standard solution. 

When similar photolysis of 11 in the presence of MeOD was carried out, again the product whose NMR reveals the resonance due to the Si-H proton was observed. The relative ratio of the Si-H and CH3-0 protons was identical with those of the products obtained in the presence of non-deuterated methanol. The formation of the methoxysilyl group can be understood by the addition of methanol across the silicon-carbon double bonds. H NMR spectra of all photoproducts obtained from the photolyses of 11 in the presence of methanol reveal no resonances attributed to the cyclohexadienyl ring protons. This indicates that the photochemical degradation of the polymer 11 gives no rearranged silene intermediates, but produces... 

A flow cell-procedure was then applied. The experiment consisted of (a) adsorption of methanol (in a solution containing deuterated methanol and light hydrogen base electrolyte), (b) solution exchange with base electrolyte and (c) application of two potential steps, one of short duration to oxidize the adsorbed residue and then a second one in the negative direction to reduce the ions H+ and/or D+ formed. During this time the mass intensity signals for HD, (m/e = 3) and for COz (m/e = 44) were... 

Isomerization of betaines 20k, 1 to silylated phosphorus ylides was also confirmed by their reaction with methanol-Ji, which occurs rather rapidly at room temperature to give Me2Si(OMe)2 and mixtures of a-deuterated phosphonium salts 72k, 1 (Scheme 33). It is most probable that, in this case, the reaction occurs mainly through the intermediate formation of a-silylated... 

When l,3r5-triazine is allowed to react with dinitrogen pentoxide and quenched with methanol the cis and trans isomers of 13 3-trinitro-2,4,6-trimethoxy-hexahy drotriazine are obtained. Nitration of the triazine in deuterated nitromethane at -10 °C affords the mixture of cis and trans 2,4,6-trinitrato-l,3,5-trinitro-hexahydro-13,5-triazines which are decomposed at room temperature . Hexahydro-13,5-triaryl-133-triazines cyclorevert upon exposure to HC1 gas to give solid arylmethylene iminium chlorides as new versatile reagents... 

TO test the reactor and analysis system, pulses of methanol, singly, and completely deuterated methanol were led over the commercial Pe (MoO.) VtoO, catalyst and the two separate phases, m this way, we can check-3if a kinetic isotope takes place on the separate phases, and the measurements can be extended to a larger temperature range more readily than under steady state conditions. The pulses contained about 12% methanol in argon and 10% oxygen. 

The conclusions on the rate limiting step are again supported by the differences in product selectivity if completely deuterated methanol is used the selectivity to dimethylether relative to formaldehyde is much larger. This is shown for the three catalysts in Figures 10-12, in which the ratio of the amounts of dimethylether and formaldehyde formed is plotted as a function of temperature. In the case of CH,0D, the water observed is a mixture of H20, HDO, and D20, most of it being HDO. 

Halcinonide dissolved in either methanol, deutero-methanol, aqueous ammonia-methanol, or deuterium oxide deuter-ated ammonia-methanol solvents appears stable after storage for six days at 50°, using nuclear magnetic resonance and mass spectrometry.70... 

---