Deuterated media

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. 

The reactions have also been studied in deuterated media, the corresponding values of the terms 3 and k are 8.56x10 mole.l . sec and 1.02x10 mole. l . sec (at 24.9 °C, n = 2.2 M perchlorate media) an overall activation... 

An alternative explanation by Schrauzer and collaborators138,139 assumes mononuclear vanadium(II) as a two-electron reductant dinitrogen would be reduced in a first step to N2 . N2 and hydrazine would be obtained by disproportionation of N2H2 (diazene), inside the Mg(OH)2 lattice, which would protect the diazene from rapid decomposition to the elements. On reducing acetylene in deuterated media, the resulting ethylene was exclusively cis.139... 

Phosphinites and phosphinates exchange with deuterated media ... 

A terminal water or hydroxyl ligand is another source of proton hyperfine couplings in metalloproteins. Characteristically, these protons can usually be exchanged in deuterated media (unlike the constitutive protons discussed above), allowing for complementary H ENDOR studies on the exchanged samples. For example, ENDOR resonances from exchangeable... 

The nature of the free radical was established in a series of isotope substitution experiments in which reductase-overproducing bacteria grew in deuterated media with... 

The inhibitory effects of deuterium on the cellular level were not reversed by gibberellic acid, naphthalene-acetic acid or indoleacetic acid. In some instances the inhibitory effects on growth were even greater than that attributable to the D2O in the nutrient. It is interesting to note that maleic hydra-zide, usually considered to be a plant growth inhibitor, actually stimulated the growth of peppermint cultured in deuterated media. 

The pyrolyses of JV-nitroso-A-acetylamines also probably generate ion pairs in the usual non-polar reaction media, e.g. />-cymene, for little rearrangement is reported Diazoalkanes, formed by elimination from diazohydroxides, are unlikely intermediates in nitrous deamination, for neither ethylamine nor isobutylamine gives labelled products when the reaction is conducted in deuterated media these observations also exclude 7r-complex intermediates -... 

Norbomene-derived anilide 3 was chosen as starting material in the isotope labeling experiments that are collected in Scheme 39.3. When the reaction of 3 with IBX was performed in deuterated media [THF- /s/DMSO- /tf (10/1)], deuterated product 4 was obtained. 

Melittin and SD-LgKeC. ESEEM of spin-lahelled peptides in deuterated media was studied for the 26-mer hee venom melittin, and for a de-novo designed 15-mer o,L-amino acid amphipathic peptide (5D-LgKeC), both of which are antimicrobial. The spin prohe MTSSL (l-0)grl-2,2,5,5-tetramethyl-3-pyrroline-3-methyl methanethiosulphonate) vras attached to the peptides through a specific cysteine, located at the N-terminus of the peptide chain. The phospholipids used were DPPC, ePC, egg phosphatidylglycerol (PG) and phosphatidylethanolamine (PE). 

Such a mechanism requires that the major product, 1,2,4-trichlorobenzene should contain deuterium when the reaction is performed in a deuterated medium , but the amount of label found was no greater than predicted from the rate of exchange of the product under the reaction conditions . Presumably fairly extensive double-bond character is exhibited in the transition state for bimolecular elimination from the benzene hexachlorides and the abnormally high activation energy for the beta isomer is most plausibly attributed to the lack of coplanarity in the iy -c//nfl/-elimination or the high energy and low population of the boat conformer required for jy/i-elimination. Alternatively, a sparsely populated conformation for a concerted syn-clinal-... 

Oleinick and Koritz (1966) have studied the isomerization of androst-5-ene-3,17-dione in a deuterated medium under several sets of conditions (a) enzyme catalysis by a rat adrenal microsomal fraction activated by DPN (b) nonenzymatic reaction at pH 7.0 (c) acid catalysis, and (d) base catalysis. They used infrared spectra of the various possible deuterium-labeled androstenediones to determine the positions of D-incorporation into the molecule (see Malhotra and Ringold, 1964). The position of the deuterium label was determined by the C—D stretching frequencies C-6P, 2140 cm" C-6a, 2190 cm C-4, 2255 cm" C-ip, 2140cm" and C-2,2, 2140 cm and 2220 cm . 

A replacement culture technique was developed by Crane et (27) to study the effect of deuteration on alkaloid production in Atropa belladonna. Plants were grown to maturity in an aqueoui (HoO) medivim and were then transplanted to media containing 50, 60, 75 and 99.7 percent D2O. The plants in 99.7 percent D2O showed the drastic effects of deuteration almost immediately and all plants died in several days. Plants transplanted into 75 percent D2O survived about 3 weeks, and the 50 and 60 percent D2O plants withstood the stresses imposed by deuteriiam. These plants were harvested after a growth period of 7.5 months. Alkaloid production was reduced to from one-third to one-tenth that of the control plants. The absolute amount of alkaloid formed and the total amount of plant material produced were too small to permit isolation of alkaloid. It appeared from this study that alkaloid production was completely inhibited upon transfer of the plants from normal growth in H20 to the deuterated medium. 

PS II particles were prepared from spinach according to [5] with the modifications reported in [6]. Tris washing was accomplished as decribed in [7]. These particles will be labeled PS n/Tris particles. The PS E/Tris particles were resuspended in DjO for 3 days at 4 C according to the procedure of [8] to promote the substitution of exchangeable protons by deuterons. These particles will be labeled PS E/Tris/DjO. Chlorella (C.) vulgaris cells were grown on a fully deuterated medium, concentrated and resuspended in 20 mM Hepes (pH 7.5) and O.I M KCl. The experiments were carried out at 5 K on a home-built phase-sensitive ESE spectrcMneter described elsewhere [9]. The repetition rate of the microwave pulse sequence was 100 or 500 Hz. 

The 1773 (B) and 1770 (R) bands shift to 1762 and 1756, respectively, in deuterated medium. When rhodopsin is reconstituted from retinal labeled at C-15 with or with H, these bands do not shift positions. They are therefore due to the free carboxylic groups of either aspartic or glutamic acid residues rather than the chromophore. The difference spectra show that the environment of a carboxylic group changes slightly in going from R to B. 

The results obtained in the irradiation of 4 with D20-MeCN support the SET-based mechanism proposed in Scheme 16.4. In this case, the first step in the deuterated medium should be the exchange of the acidie protons with the solvent. After the SET proeess, charged-separated dirradical 9 should be formed. Subsequent deuterium transfer in 9 followed by loss of CO2 would give deuterated azo-methine ylide 10 that after deuterium transfer finally yields the observed y-labeled A-phthalimidobutyric acid 5 (Scheme 16.5). 

Hartshorn and Ridd48 showed that there is a negligible solvent isotope effect on nitrating anilinium ions in sulphuric acid and deuterated sulphuric acid (cf. an earlier less accurate determination by Brickman and Ridd48). The absence of a solvent isotope effect also argues against reaction on the free base because the free base concentration would be lower by a factor of about four in the deuterium-containing medium. Consequently, the differences in the rate coefficients in Table 6... 

The rate of deuteration of (XXXIII) at the 3 position by ca. 0.1 M NaOD in D20 was 2.19 times faster than the dedeuteration of the same position by the same concentration of NaOH in H20 at 35 °C. This indicates that proton transfer takes place in a rate-determining step, but the result is not conclusive in view of the different reaction medium. 

The alcohol 3) , 28-diacetoxy-6 -hydroxy-18i -12-oleanene was oxidised in an aqueous acetic acid medium Deuteration at the six position had no effect on the rate in solvents of high (> 80 %) acetic acid content, but the isotope effect reached 2 in 60 % acetic acid. Increasing the acetic acid content of the medium produced a much larger effect on the oxidation rate of cyclohexanol than of the polycyclic alcohol. 

Cultures of S. obliquus can easily be grown photoautotrophically in two-tier flasks in an inorganic medium. A stepwise replacement of H20 by 2H20 leads to deuterated cultures, and a replacement of C02 (the sole carbon source) by 13C02 and/or the replacement of... 

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