Formation and Mechanism for Reactions of Ring-Substituted Phenonium Ions in Aqueous Solution.

The results of studies on the structure and reactivity of spiro[5.2]oct-5,7-diene-4yl carbocation [phenonium ion] have had a significant impact on the course of discussion about the distinction between classical and nonclassical carbocations. This minireview will present a brief overview of the structure, bonding and reactivity of ring substituted phenonium ions (), with an emphasis on work completed since 2004.

Swain-Scott Relationships for Nucleophile Addition to Ring-Substituted Phenonium Ions.

The products of the reactions of 2-(4-methoxyphenyl)ethyl tosylate () and 2-(4-methyphenyl)ethyl tosylate () with nucleophilic anions were determined for reactions in 50/50 (v/v) trifluoroethanol/water at 25°C. In many cases the nucleophile selectivity / (M) for reactions of nucleophile and solvent, calculated from the ratio of product yields, depends upon [Nu]. This demonstrates the existence of competing reaction pathways, which show different selectivities for reactions with nucleophiles.

Risk Factors for Prolonged Treatment of Whiplash-Associated Disorders.

Objectives: Whiplash-associated disorders (WAD) are the most common injuries that are associated with car collisions in Japan and many Western countries. However, there is no clear evidence regarding the potential risk factors for poor recovery from WAD. Therefore, we used an online survey of the Japanese population to examine the association between potential risk factors and the persistence of symptoms in individuals with WAD.

Substituent Effects on the Formation and Nucleophile Selectivity of Ring-Substituted Phenonium Ions in Aqueous Solution.

The reaction of 2-(4-methyphenyl)ethyl tosylate () in 50/50 (v/v) trifluoroethanol/water at 25 °C is first-order in the concentration of azide anion nucleophile. A carbon-13 NMR analysis of the products of the reactions of in 50/50 (v/v) trifluoroethanol/water at 25 °C shows the formation of , and from the trapping of a symmetrical 4-methylphenonium ion reaction intermediate . The formation of by concerted bimolecular displacement of azide ion at ( = 3.

Formation and stability of the 4-methoxyphenonium ion in aqueous solution.

The reaction of 2-methoxyphenylethyl tosylate (MeO-1-Ts) is first-order in [N(3)(-)]. A carbon-13 NMR analysis of the products of the reactions of MeO-1-[α-(13)C]Ts shows the formation of MeO-1-[β-(13)C]OH and MeO-1-[β-(13)C]N(3) from the trapping of a symmetrical 4-methoxyphenonium ion reaction intermediate 2(+). An analysis of the rate and product data provides a value of k(az)/k(s) = 83 M(-1) for partitioning of 2(+) between addition of azide ion and solvent.

Interaction between Al3+ and acrylic acid and polyacrylic acid in acidic aqueous solution: a model experiment for the behavior of Al3+ in acidified soil solution.

From the viewpoint of the phytotoxicity and mobility of Al(3+) released from soil minerals due to soil acidification, the interaction between Al(3+) and acrylic acid (AA) and polyacrylic acid (PAA) as a model compound of fulvic acid was investigated. The interaction was examined at pH 3 so as to avoid the hydrolysis of Al(3+). The interaction between Al(3+) and AA was weak.

Dynamics for Reactions of Ion Pairs in Aqueous Solution: Reactivity of Tosylate Anion Ion Paired with the Highly Destabilized 1-(4-Methylphenyl)-2,2,2-Trifluoroethyl Carbocation.

The sum of the rate constants for solvolysis and scrambling of carbon bridging and nonbridging oxygen-18 at 4-MeC(6)H(4)CH(CF(3))OS((18)O(2))Tos in 50/50 (v/v) trifluoroethanol/water, (k(solv) + k(iso)) = 5.4 × 10(-6) s(-1), is 50% larger than k(solv) = 3.6 × 10(-6) for the simple solvolysis reaction of the sulfonate ester.

Formation of a silicato complex of zinc in aqueous solution and its accelerating effect on the formation of silica scales in cooling water systems.

This study elucidates the effect of zinc (Zn), which is an anticorrosive water additive, on the formation of silica scales from cooling water. In these experiments, the silica scales were analyzed by EPMA, and the results indicate that Zn is sorbed into the silica scales during formation. Measurements of the solubility of Zn(OH)(2) at various concentrations of silicic acid demonstrate that Zn is present as a silicato complex of Zn (SCZ) in cooling water.

When does an intermediate become a transition state? Degenerate isomerization without competing racemization during solvolysis of (S)-1-(3-nitrophenyl)ethyl tosylate.

(S)-1-(3-Nitrophenyl)ethyl tosylate [(S)-2-OTs] was prepared in >99% enantiomeric excess and the change in the chiral purity of this compound was monitored during solvolysis in 50:50 trifluoroethanol/water. The barely detectable formation of 0.5% (R)-2-OTs after two half times for the solvolysis reaction was used to calculate a rate constant of k(rac) approximately equal to 4 x 10-6 s-1.

[Prostate cancer detection by prostate biopsy among Japanese with prostate-specific antigen below 4.0 ng/ml].

The cases of prostate cancer diagnosed at our hospital after the introduction of transrectal ultrasound-guided prostate biopsy were analyzed to ascertain the cancer detection rate among individuals with a prostate-specific antigen (PSA) below 4.0 ng/ml and to assess the pathological characteristics of the prostatectomy specimens. During the period from January 1997 to December 2003, 1,167 individuals received prostate biopsies at our hospital.

Reactions of ion-pair intermediates of solvolysis.

The detection during solvolysis of competing signature reactions such as the racemization of a chiral substrate, or the scrambling of oxygen isotopes at the leaving group serves as evidence for a stepwise mechanism that proceeds through a reversibly formed ion-pair intermediate. We have examined these signature reactions and determined the relative rates of competing solvolysis, isomerization, and racemization reactions of neutral ring-substituted 1-phenylethyl derivatives. These data were used to define the relative rate constants for partitioning of carbocation-anion pairs between dynamic processes such as reorganization of the ion pair within a solvent cage, and migration of the leaving group anion from the "top" to the "bottom" face of the planar carbocation.

Infection-induced urethral defect treated by urethral reconstruction with a radial forearm flap.

Abstract A 47-year-old man was admitted with the chief complaint of a urethral defect. An approximately 17-cm defect of the urethra seemed to have been occurred by the infection of implanted foreign bodies in the penile skin. Reconstruction of the urethra and the ventral skin was performed with a free radial forearm flap.

Early catheter removal and postoperative status of bladder outflow after retropubic radical prostatectomy.

Cystography was performed on 35 patients 6 to 7 days after retropubic radical prostatectomy (RRP), to determine the feasibility of early removal of the urinary catheter. The urethral catheter was removed the same day if no extravasation was evident on cystography. Uroflowmetry was also performed both immediately after early catheter removal and at follow-up 4 to 20 months later.

[A case of pyonephrosis caused by a protein calculus in a patient on hemodialysis].

We report a case of pyonephrosis caused by a protein calculus in a patient on hemodialysis. A 56-year-old man had been treated with dialysis for five years because of end-stage renal failure. The patient complained of right lumbar back pain and fever.

[Combination therapy with estramustine and docetaxel for hormone refractory prostate cancer].

Six patients with hormone refractory prostate cancer were orally administered 560 mg of Estramustine daily in 2 equally divided doses for four or five days. In addition 70 mg/m2 of Docetaxel was infused through intravenous drip from day 1, decreasing to 40-60 mg/m2 if any side effects such as bone marrow depression were observed. One cycle was three weeks in hospital and one month after discharge.

Scrambling of oxygen-18 during the "borderline" solvolysis of 1-(3-nitrophenyl)ethyl tosylate.

[reaction: see text] There is substantial isomerization (kiso=0.32 x 10(-3) s(-1)) of 3-NO2C6H4(13)CH(Me)OS(18O)2Tos during solvolysis (ksolv=1.04 x 10(-3) s(-1)) in 50/50 trifluoroethanol/water, even though the estimated lifetime of the putative 1-(3-nitrophenyl)ethyl carbocation intermediate of solvolysis (ca.

Kinetic and thermodynamic barriers to carbon and oxygen alkylation of phenol and phenoxide ion by the 1-(4-methoxyphenyl)ethyl carbocation.

Rate constant ratios for addition of the three nucleophilic sites of phenol to the 1-(4-methoxyphenyl)ethyl carbocation (1+) in 50/50 (v/v) trifluoroethanol/water were determined from the relative yields of the three phenol adducts, and absolute rate constants were determined from product rate constant ratios for addition of phenol and azide ion to 1+ using k(az) = 5 x 10(9) M(-1) s(-1) for the diffusion-limited reaction of azide ion. A selectivity of 230:20:1 was determined for alkylation of phenol at oxygen, C-4 and C-2 to form 1-OPh and biphenyls 1-(4-C6H4OH) and 1-(2-C6H4OH), respectively, and of 2:2:1 for alkylation of the corresponding nucleophilic sites of phenoxide ion in diffusion-limited reactions. The Mayr nucleophilicity parameter for C-4 of phenol is N = 2.

[Clinical study of chemoradiotherapy using low dose cisplatinum as X-ray intensifier in patients with urothelial carcinoma].

Chemoradiotherapy using cisplatinum (CDDP) as the X-ray intensifier was performed on patients with urothelial carcinoma. Ten lesions in 9 patients, 6 patients with postoperative relapse and 3 who received the therapy as a palliative treatment for progressive carcinoma, were evaluated. Four of the patients with postoperative relapse had undergone adjuvant chemotherapy.

3-(Trifluoromethyl)indenyl Cation: Ion Pair Return in the Formation of an Antiaromatic and Electron-Deficient Doubly Destabilized Carbocation.

The solvolysis of 3-(trifluoromethyl)-3-indenyl tosylate (15) occurs with extensive isomerization to 1-(trifluoromethyl)-3-indenyl tosylate (16), which reacts in a slower process to give the substitution product 17. Kinetic analysis of a model involving an intermediate allyl cation/tosylate ion pair 18 gave a partitioning ratio in CD(3)CO(2)D at 99.6 degrees C for 18 of 7.