Synthesis of 3-aryl- and 3-aryl-3,4-dihydroisocoumarins

611-615The condensation of homophthalic acid 6 with the appropriate acid chlorides 7a-c yield the respective isocoumarins 5a-c, which are converted to keto-acids 9a-c by alkaline hydrolysis. The 3,4-dihydroisocoumarins 12a-c are obtained by reduction of the keto-acids 9a-c to hydroxy-acids 11a-c followed by cyclodehydration using acetic anhydride

Arsenic Contamination of Groundwater in Indus River Basin of Pakistan

Arsenic (As) contamination of drinking water from groundwater sources is an issue of public health concern in many parts of the world, including South Asia. The presence of As in groundwater of Pakistan was reported around the city of Karachi as early as 1997. Widespread occurrences of As are reported in groundwater through a number of subsequent studies in the provinces of Punjab and Sindh, the two most populated provinces in the Indus River basin of Pakistan and thereby emerged as an issue of public health concern. These studies have revealed that concentrations of As are elevated by a factor of 10–250 as compared to the WHO drinking water guideline. Both natural and anthropogenic processes have been primarily indicated as cause for elevated As concentration in groundwater. An increasing number of studies also show evidence that irrigation with As contaminated groundwater is associated with elevated As concentrations in agricultural products. The future research should therefore focus on the detailed understanding of the complexities of the geological and hydrogeological setting of Pakistan and to outline the sources of As and the mechanisms of transport to the Indus basin aquifers