Thermo Fisher Scientific Research Associate Interview Questions and Answers

Pyrophoric chemicals can be handled and quenched by using inert gases, specialized containers, and proper disposal methods.

• Use inert gases such as nitrogen or argon to displace air and prevent ignition.

• Store and handle pyrophoric chemicals in specialized containers such as air-tight glass ampoules or sealed metal containers.

• Dispose of pyrophoric chemicals properly by contacting a hazardous waste disposal company.

• Exampl...read more

Palladium and copper chemistry are widely used in organic synthesis. Some important reactions include Suzuki coupling, Heck reaction, Sonogashira coupling, and Ullmann reaction.

• Suzuki coupling: cross-coupling reaction between an organoboron compound and an organic halide or triflate catalyzed by a palladium complex

• Heck reaction: coupling of an aryl or vinyl halide with an alkene in the presence of a palladium catalyst

• S...read more

Different oxidising and reducing agents used for ester reduction, cyano reduction, and alcohol oxidation.

• Ester reduction: Lithium aluminum hydride (LiAlH4), sodium borohydride (NaBH4), diisobutylaluminum hydride (DIBAL-H)

• Cyano reduction: Lithium aluminum hydride (LiAlH4), sodium borohydride (NaBH4)

• Alcohol oxidation: Chromium trioxide (CrO3), potassium permanganate (KMnO4), Jones reagent (CrO3/H2SO4)

Some common oxidising reagents include potassium permanganate, hydrogen peroxide, chromic acid, ozone, and nitric acid.

• Potassium permanganate

• Hydrogen peroxide

• Chromic acid

• Ozone

• Nitric acid

Indicators are substances that change color in response to changes in pH levels, helping to determine the acidity or alkalinity of a solution.

• Indicators are typically weak acids or bases that dissociate in water and change color based on the concentration of H+ ions.

• Common indicators include phenolphthalein, litmus, and bromothymol blue.

• The color change of an indicator is due to a shift in the equilibrium between the a...read more