1 Due to the high degree of regio-and stereoselectivity (due to the concerted mechanism), the Diels-Alder reaction is a very powerful reaction and is widely used in synthetic organic chemistry.2  The reaction usually thermodynamically favourable due to the conversion of 2 &#960 -bonds into 2 new stronger &#963-bonds. Due to the high degree of regio-and stereoselectivity (due to the concerted mechanism), the Diels-Alder reaction is a very powerful reaction and is widely used in synthetic organic chemistry.
A standard echocardiogram or a fetal echocardiogram test usually takes about 30 to 60 minutes. A stress echocardiogram usually takes between 60 and 90 minutes.
How long does the MRI scan take? For most exams, expect to be in the department for a minimum of one hour. We need time to prepare you for your scan, and then take you into the room for the actual exam. For most body cases (exams like liver, pelvis, heart) expect to be in the department for two hours.ow long does the MRI scan take? For most exams, expect to be in the department for a minimum of one hour. We need time to prepare you for your scan, and then take you into the room for the actual exam. For most body cases (exams like liver, pelvis, heart) expect to be in the department for two hours.