Relationship with dimethyl

Structure elucidation of three related derivatives of ring system 2 ( temozolomide 9a, mitozolomide 9b, and the related acid derivative 9c) has been carried out by 13C and 15N NMR spectroscopy <1995J(P1)249> (Scheme 2). The 1SN NMR chemical shifts measured in dimethyl sulfoxide (DMSO) solutions are listed in Table 1. For compound 9a, Lowdin charges of the nitrogen atoms have also been calculated and found to have a linear relationship with the experimentally determined chemical shifts of these atoms. The NMR data of 9a have been correlated with those of a series of heterocycles of related structure by the same team <2002MRC300>. 

Stobbe reaction org chem A type of aldol condensation reaction represented by the reaction of benzophenone with dimethyl succinate and sodium methoxide to form monoesters of an a-alkylidene (or arylidene) succinic add. shtob-3 re.ak shan ) stoichiometry phys chem The numerical relationship of elements and compounds as reactants and products in chemical reactions., st6i ke am-3 tre )... 

Kiene RP, Bates TS (1990) Biological removal of dimethyl sulfide from sea water. Nature 345 702-705 Kiene RP, Linn LJ (2000) Distribution and turnover of dissolved DMSP and its relationship with bacterial production and dimethylsulfide in the Gulf of Mexico. Limnol Oceanogr 45 849-861... 

The relationship between macrorine (mp 160°) and isomacrorine, (mp 110°) is shown by their formation of a common methiodide (mp 196°) on thermal decomposition this gives macrorine and only a trace of isomacrorine. Methylation of normacrorine (mp 156°-167°) with dimethyl sulfate gives a 2 1 mixture of macrorine and isomacrorine. 

In vivo studies with C-labeled precursors established that Archaea generate riboflavin via 6,7-dimethyl-8-ribityllumazine. A protein with riboflavin synthase activity was purified from Methanothermobacter thermoautotrophicus, and the cognate gene was cloned by a marker rescue strategy. The peptide of 154 amino acid residues showed no intramolecular sequence similarity and no sequence relationships with the riboflavin synthases of eubacteria and eukarya. 

The variations of /uc- h d 7ih-ih acetone and dimethyl sul-phoxide in various solvents show an almost linear relationship with the carbonyl-and chemical shifts/ " Hydrogen bonding with the solvent, or the presence of large solvent dipoles, may increase the relative importance of polar resonance structures of the carbonyl or sulphoxide group (33), and the electron withdrawl experienced by the methyl group will result in increased values of C—H couplings. 

This relationship is valid for a matched screw geometry. The apex leakage term V12 is determined by the apex width cubed see Eq. 10.103. Thus, increases in the apex angle will cause very strong increases in the apex leakage flow. Figures 10.53 and 10.54 compare output predictions made with Eq. 10.105 to the experimental results obtained by Nichols with dimethyl-siloxane polymeric fluids [19]. 

A symmetry approach to the effect of temperature and substitution on Cope rearrangements has revealed that with increasing temperature the loss of symmetry can be considered as a collective variable which has a positive linear relationship with temperature. The results of an aromatic Cope rearrangement of a trans-l-aryl-2-ethenylcyclobutanecarbonitrile have been reported for the construction of the fused benzocyclooctene ring. The effects of gem-dimethyl substitution on the cyclopropane, alkene geometry, relative stereochemistry of the cyclopropane, and steric and electronic effects of functional groups on the thermal Cope rearrangement of divinylcyclopropanes have been reported (Scheme 10). " ... 

Their activity with respect to esterification and alcoholysis has been compared by Habib and Malek [105,106] and Chung [107], who found volcano-shaped relationships with different optima of activity of the several metals in terms of metal electronegativity according to Tanaka [108] for the glycolysis of dimethyl terephthalate... 

Relationships connecting stmcture and properties of primary alkylamines of normal stmcture C, -C gin chloroform and other solvents with their ability to extract Rh(III) and Ru(III) HCA from chloride solutions have been studied. The out-sphere mechanism of extraction and composition of extracted associates has been ascertained by UV-VIS-, IR-, and H-NMR spectroscopy, saturation method, and analysis of organic phase. Tertiary alkylamines i.e. tri-n-octylamine, tribenzylamine do not extract Ru(III) and Rh(III) HCA. The decrease of radical volume of tertiary alkylamines by changing of two alkyl radicals to methyl make it possible to diminish steric effects and to use tertiary alkylamines with different radicals such as dimethyl-n-dodecylamine which has not been used previously for the extraction of Rh(III), Ru(III) HCA with localized charge. 

The copolymers are prepared using a mixture of dimethyl terephthalate and dimethyl naphthalate. Published data indicates a reasonably linear relationship between and copolymer composition on the lines discussed in Section 4.2, e.g. Tg for a 50 50 copolymer is about 100°C which is about mid-way between Tg figures for the two homopolymers. In line with most other copolymers there is no such linearity in the crystalline melting point (T, ). As comonomer levels are introduced drops from the values for both homopolymers and indeed crystallisation only readily occurs where one of the components is dominant, i.e. 80%. Thus commercial copolymers are usually classified into two types ... 

Brown and McDonald (1966) provided another type of kinetic evidence for these size relationships by determining secondary kinetic isotope effects in reactions of pyridine-4-pyridines with alkyl iodides. For example, the isotopic rate ratio in the reaction between 4-(methyl-d3)-pyridine and methyl iodide at 25-0 C in nitrobenzene solution was determined to be kjyfk = l-OOl, while that in the corresponding reaction with 2,6-(dimethyl-d6)-pyridine was 1-095. (Brown and McDonald (1966) estimate an uncertainty of 1% in the k jk values.) Furthermore, the isotopic rate ratio in the case of the 2-(methyl-d3)-compound increased from 1 030 to 1-073 as the alkyl group in the alkyl iodide was changed from methyl to isopropyl, i.e. the isotope effect increased with increasing steric requirements of the alkyl iodide. 

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