Cyclohexanols shifts 210

In Problem 5 17 (Section 5 13) we saw that acid catalyzed dehydration of 2 2 dimethyl cyclohexanol afforded 1 2 dimethylcyclohexene To explain this product we must wnte a mecha nism for the reaction in which a methyl shift transforms a secondary carbocation to a tertiary one Another product of the dehydration of 2 2 dimethylcyclohexanol is isopropyhdenecyclopentane Wnte a mechanism to rationalize its formation... 

Studies in surface-inactive electrolyte solutions with various organic compounds (cyclohexanol, 1-pentanol, 2-butanol, camphor, tetra-buthyl ammonium ion, TBN+) show that the adsorption-desorption peak shifts to more negative potentials in the order (0001) < (1010) < (1120) this was explained by the increasing negative value of Eff=0 in the same direction.259 629-635... 

Fe electrodes with electrochemically polished (cathodically pretreated for 1 hr) and renewed surfaces have been investigated in H20 + KF and H20 + Na2S04 by Rybalka et al.721,m by impedance. A diffuse-layer minimum was observed at E = -0.94 V (SCE) in a dilute solution of Na2S04 (Table 19). In dilute KC1 solutions E,njn was shifted 40 to 60 mV toward more negative potentials. The adsorbability of organic compounds (1-pentanol, 1-hexanol, cyclohexanol, diphenylamine) at the Fe electrode was very small, which has been explained in terms of the higher hydro-philicity of Fe compared with Hg and Hg-like metals. 

Adsorption of various organic compounds (e.g., cyclohexanol, adamantanol-1, and camphor) has been studied at a renewed Sn + Pb alloy/electrolyte interface.820-824 The time variation of the surface composition depends on the solution composition, the nature and concentration of the surface-active substance, and on E. The " of cyclohexanol for just-renewed Sn + Pb alloys shifts toward more negative E with time, i.e., as the amount of Pb at the Sn + Pb alloy surface increases. 

The H NMR spectra of the epimeric cyclohexanols in DMSO reveal that the hydroxyl proton in the axial alcohol shows a resonance absorption at a higher field than in the equatorial one, indicating that the conformational effect of the hydrogen bond influences the NMR chemical shifts . 

Thermolysis of allylic nitro compounds results in the formation of rearranged allyl alcohols the cyclohexene 416, for instance, affords a 4 1 mixture of the cyclohexanol derivatives 417 and 418. It is proposed that the process involves a [2,3] sigmatropic shift of a nitro group (equation 137)451. 

For the a-SCS(OH) values in cyclohexanol derivatives Wray (406) has suggested that a further parameter is necessary to account for four-bond interactions, as indicated in 298 and 299. He remarked that significant deviations from the experimental chemical shifts indicate conformational distortion of the parent compound, and that such SCS values cannot be calculated for five-membered ring alcohols (406). 

In analogy to the a-hydroxy effects in cyclohexanols (vide supra), the chemical shifts of anomeric atoms in pyranoses are often stereochemistry dependent, as seen for the C-l shifts of the following hexopyranoses in deuterium oxide41-45. 

Alcohol carbons are identified by spectral comparison of the alcohol with the corresponding acetate Upon acetylation of cyclohexanols the a-carbons shift about 3 to 4 ppm downfield and the /i-carbons move 2 3 ppm upheld. Esterification of axial hydroxy groups also causes a downfield shift of 1 ppm of the y-carbons [65 a]. 

Some other catalytic events prompted by rhodium or ruthenium porphyrins are the following 1. Activation and catalytic aldol condensation of ketones with Rh(OEP)C104 under neutral and mild conditions [372], 2. Anti-Markovnikov hydration of olefins with NaBH4 and 02 in THF, a catalytic modification of hydroboration-oxidation of olefins, as exemplified by the one-pot conversion of 1-methylcyclohexene to ( )-2-methylcycIohexanol with 100% regioselectivity and up to 90% stereoselectivity [373]. 3. Photocatalytic liquid-phase dehydrogenation of cyclohexanol in the presence of RhCl(TPP) [374]. 4. Catalysis of the water gas shift reaction in water at 100 °C and 1 atm CO by [RuCO(TPPS4)H20]4 [375]. 5. Oxygen reduction catalyzed by carbon supported iridium chelates [376]. - Certainly these notes can only be hints of what can be expected from new noble metal porphyrin catalysts in the near future. 

Preparative electrolysis of cyclohexanone17 in solutions containing 0.1 M (C4H9)4NBF4 as the electrolyte were carried out at —2.95 V(SCE), more positive potentials resulted in negligible current. When 0.01 M (DMP)BF4 was added to the solution, electrolysis of cyclohexanone was possible at —2.70 V(SCE). Thus, DMP+ caused a 0.25 V positive shift in the preparative reduction potential of cyclohexanone. DMP + also altered the nature of the product. In the presence of DMP+, cyclohexanone formed only the corresponding pinacol, while in its absence cyclohexanol was the sole product. From this and experiments with other aliphatic ketones (that will be described later) it could be concluded that DMP+ catalyzes the reduction and redirects the... 

Another method involves placing the structure of a molecule on a map of the dipolar field and reading predicted shifts which are scaled with the observed shifts. Some molecules studied by this method are pyridine, ci.v-4-r-butyl cyclohexanol, and 1-adamantanol [45]. 

The predominant reaction for the formation of cyclohexanol and cyclohexanone is the Russell mechanism of decomposition of secondary cyclohexylperoxy radicals, vhich first yields the product of coupling and then reacts by a non-radical, six-center 1,5-H-atom shift (termination of the radical-chain sequence) ... 

For cyclohexanol adsorption on the three faces of lowest indices of zinc (in 100 mM KCl + 0.1 mM H2SO4), C(E) curves are given in Fig. 50. Obviously, only one of the adsorption-desorption peaks is observable in the dl region. These results were shown to fit the two-parallel-capacitors model (dashed lines). For a given concentration of adsorbate, the potentials of the peak and of the maximum of adsorption shift in the same order as the pzc s in base electrolyte. From the complete analysis of the curves, all adsorption parameters were found to be co dependent.f... 

Anionic copper(II)phthalocyanine monosulphonate (CuPcMs) and copper(II) phthalocyanine tetrasulphonate (CuPcTs) complexes have been successfully intercalated into the intergallery of Mg-Al layered double hydroxides through direct synthesis method. XRD results indicated an inclined orientation of the anion in the interlamellar space. A better thermal stability was noticed for the macrocycle ligand upon intercalation. The visible spectra showed a hyspochromic shift upon intercalation indicating disturbance of the macrocycle ligand pltmarity. An enhanced activity for the selective oxidation of cyclohexanol to cyclohexanone was observed for the intercalated complex in comparison with neat complex. 

Amylose is a unique polysaccharide which forms a helical blue-coloured complex with iodine (I5). It also forms helical complexes with a variety of organic compounds such as 1-butanol, 1-pentanol, cyclohexanol, SDS etc. The interaction of SDS, a competing ligand with iodine (I ) complexes of amylose and amylopectin is studied spectrophotometrically. It is observed that the reduction in absorbance at 640 nm accompanied by the blue shift (640-570 nm) in the absorption spectrum is governed by the sequence of addition of the reagents, implying that this Interaction is closely associated with the coil—>hellx transition of the polymer chain. Perturbation of this complex with sodium thiosulphate and urea has revealed that the transition from helix—>coil is rather sluggish and hydrophobic interactions play an important role in the stability of this complex. 

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