Nitroalkane Anomaly: Computational Study with Cluster and Continuum Modeling

The origin of anomalous relation between rates and equilibria for the proton-transfer reactions of nitroalkanes, known as nitroalkane anomaly, was investigated by theoretical calculations with a cluster model, in which three water molecules are explicitly considered in the system, as well as the PCM solvent continuum model. For the CH3NO2/CH3CH2NO2 system, B3LYP and MP2 computations reproduced the anomaly, and the imbalance in the charge distribution at the transition state (TS) was observed. In contrast, although the TS imbalance was detected for the substituted phenylnitromethane system, the Brønsted plots did not show any anomaly. The experimentally observed abnormally large Brønsted coefficient (a ~ 1.4) for this system does not arise from the charge imbalance at the saddle point structure, but is likely due to the effect of the reaction dynamics

Dynamic path bifurcation for the Beckmann reaction: observation and implication

The reaction of oximes to amides, known as the Beckmann rearrangement, may undergo fragmentation to form carbocations + nitriles instead of amides when the cations have reasonable stability. The reactions of oxime derivatives of 1-substituted-phenyl-2-propanones and 3-substituted-phenyl-2-butanones in aqueous solvents gave both rearrangement and fragmentation products, the ratio of which was dependent on substituents. Transition state (TS) optimizations and intrinsic reaction coordinate (IRC) calculations for the reaction of 1-phenyl-2-propanone oximes showed that there is a single TS for each substituted compound. The IRC path from the TS either led to a rearrangement product or a fragmentation product depending on the substituent; the IRC path changes from rearrangement to fragmentation when substituent X becomes more electron donating. Ab initio dynamics simulations were found to follow the IRC path for X = p-NH2 and p-MeO giving fragmentation products, and almost so for X = p-NO2 giving the rearrangement products. However, in a borderline case where X is less donating than p-MeO or less withdrawing than p-NO2, the trajectories did not follow the minimum energy path on the potential energy surface, but gave both rearrangement and fragmentation products directly from the single TS. This is a novel example of path bifurcation for a closed shell anionic reaction. It was concluded that a reactivity-selectivity argument based on the traditional TS theory may not always be applicable even to a well-known textbook organic reaction

Gastric outlet obstruction possibly secondary to ulceration in a 2-year-old girl: a case report

Gastric outlet obstruction due to ulceration is extremely rare in childhood. We report a case of gastric outlet obstruction possibly secondary to peptic ulceration and our surgical management. Our approach, without vagotomy or antrectomy, would appear to be a safe and effective

Treatment of vesico-ureteral reflux in infants and children using endoscopic approaches

Abstract Vesicoureteral reflux (VUR) represents one of the most significant risk factors for acute pyelonephritis in children. Endoscopic treatment of VUR dates back to 1981 when Matouschek first described injection of the ureteral orifice in an attempt to correct VUR. In addition, also Politano and colleagues and McDonald described successful correction of reflux using endoscopic techniques. After these reports subureteral Teflon injection (STING) came to be appreciated as a viable new way to less invasively correct one of the most common pediatric urologic problems. The technique is technically easy to perform and is usually performed as an outpatient procedure. It is performed in general anesthesia in children and may require repeat injections, particularly in patients with high-grade reflux. As for endoscopic technique, a main problem existed. The success in children with high grade reflux was less than reported for open or laparoscopic reimplant techniques. However, in the past 10 years, newer products have become available that are changing the indications for endoscopic correction. In these review, we analyzed the papers published in the literature on this topic to give to the readers an updated overview about the results of endoscopic treatment of VUR after 30-years of his first description

Angiomyolipoma of the tunica dartos of the scrotum in infancy

AbstractA 12-month-old boy presented with left scrotal swelling. The mass was irregular, soft, fleshy, and nontender. It adhered to the scrotal skin and gradually enlarged. Operative findings revealed a mass fixed to the scrotal fundus and diagnosed as angiomyolipoma. This is apparently the first report of scrotal angiomyolipoma in infancy

Congenital diaphragamatic hernia associated with aortic coarctation: a case report

Congenital diaphragmatic hernia associated with cardiac anomalies is a major therapeutic challenge. We report a case of Congenital diaphragmatic hernia associated with coarctation of the aorta