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An efficient solvent free method is developed for the preparation of structurally diverse 1-alkoxymethylphosphonium chlorides in high yield. One of the prepared salts derived from (1 R,2S,5R)-(−)-Menthol auxiliary was further employed for the synthesis of vinyl ethers, where up to 99% stereoselectivity was achieved.

A facile, efficient and general synthesis of a broad range of structurally variant alkoxymethylphosphonium tetrafluoroborates (2a–e) is described. The reaction involves the triphenylphosphination of bis-alkoxy methanes in the presence of ethereal boron trifluoride at room temperature. Application of these new salts to carbon homologation of aldehydes is also studied.

Rational evaluation of the long-term performance of large-scale foundations, tunnels and natural slopes located in seismically active areas necessitates accurate assessment of the strength and deformation characteristics of bounded geomaterials, such as natural rocks and cemented soils, under creep and cyclic loading conditions. In the present study, a unique approach for examining the induced instantaneous loading/strain rates during unconfined creep and cyclic loading was adopted to unveil the effects of creep and cyclic loading on the mechanical behaviour of laboratory-produced bounded geomaterial, namely Gypsum Mixed Sand (GMS). At first, a series of unconfined monotonic tests at six different strain rates ranging from 5.3E+0 to 2.1E-5%/min were conducted on GMS. Subsequently, the mechanical behaviour of the GMS was examined under unconfined creep/sustained loading at four different stress levels. Further, these results were compared with a number of unconfined cyclic loading tests performed at different stress amplitudes. Identical patterns of the variations of axial strain accumulation and instantaneous strain rates were observed during the creep and cyclic loading. Based on the relationships between the failure stress/strain and the corresponding instantaneous strain rate, the mechanical behaviour of the GMS specimens subjected to creep and cyclic loading was found to be similar to each other, and was distinctively different than those under monotonic loading condition.

The surface displacements of slopes have been considered as a significant indicator in landslide investigations in last several decades, while in recent years the tilting of slope surfaces is also being recognized as an important index in landslide monitoring. However, the slope surface tilting has been rarely examined so far, and requires detailed investigations. In this paper, a series of laboratory tests and a field test were performed to investigate the surface tilting in rotational landslides, as well as the correlation between tilt angles and displacements of slope surfaces. In the laboratory tests, slope models were constructed with different shapes of pre-designed slip surfaces, and tested under varying test conditions. The tilting behavior of the slope surfaces in laboratory tests was measured using tilt sensors embedded into the slopes, while the surface displacement was obtained by tracing the movement of marked points set on the slope surfaces near to the tilt sensors. The test results revealed a linear relationship between the tilt angles and displacements of slope surfaces in the process of slope failure, and this linear relationship was validated by a field test in which the slope failure was triggered by artificial rainfall. The test results also indicated that the coefficient of the linear relation is consistent with the value of real distance between the locations of tilt sensors and the centers of slip surfaces. An equation that relates the slope surface tilting and displacements was proposed in this study. Furthermore, a method to estimate the geometry of the slip surface was also developed, which was deduced from the observation that the path of the sliding masses was parallel to the slip surface according to the results of laboratory tests. Additionally, an acceleration stage of surface tilting was observed in slope failure induced by artificial rainfall, which implies that the surface tilting measurement can be used to predict the potential development of a rotational landslide or its reactivation.

An efficient one pot method for the synthesis of α-alkoxymethylphosphonium iodides is developed by using PPh3/I2 combination at room temperature. Reaction conditions are found general to synthesize wide range of structurally variant alkoxymethylphosphonium iodides in high yield (70–91%). These new functionalized phosphonium salts are further used in stereoselective synthesis of vinyl ethers as well as in carbon homologation of aldehydes. Electronic supplementary material The online version of this article (10.1186/s13065-018-0421-6) contains supplementary material, which is available to authorized users.

It has been unanimously acknowledged that the strength and deformation characteristics of bounded geomaterials, viz. cemented soils and natural rocks, are predominantly governed by the rate of loading/deformation. Rational evaluation of these time-dependent characteristics due to viscosity and ageing are vital for the reliable constitutive modelling. In order to study the effects of ageing and loading/strain rate (viscosity) on the behaviour of bounded geomaterials, a number of unconfined monotonic loading tests were performed on Gypsum Mixed Sand (GMS) specimens at a wide range of axial strain rates; ranging from 1.9E-05 to 5.3E+00 %/min (27,000 folds), and at different curing periods. The results indicate shifts in the viscous behaviour of GMS at critical strain rates of 2.0E-03 and 5.0E-01 %/min. In the light of this finding, the results are categorized into three discrete zones of strain rates, and the behaviour of GMS in each of these zones is discussed. A significant dependency of peak strength and stress-strain responses on strain rate was witnessed for specimens subjected to strain rates lesser than 2.0E-03 %/min, and the effects of viscosity/strain rate was found to be insignificant at strain rate higher than 5.0E-01%/min.