Parexel International Biostatistician Interview Questions and Answers

Esters can be converted to aldehydes by hydrolysis under acidic conditions.

• Esters can be hydrolyzed to aldehydes using a strong acid, such as sulfuric acid or hydrochloric acid.

• The reaction involves the cleavage of the ester bond and the formation of a carboxylic acid intermediate, which is then further reduced to an aldehyde.

• The reaction can be carried out at elevated temperatures or using a catalyst, such as p-toluen...read more

The desired product of bromination on aniline is 2,4,6-tribromoaniline. The desired product of bromination on toluene is bromotoluene.

• Bromination on aniline results in the substitution of three bromine atoms on the aromatic ring, yielding 2,4,6-tribromoaniline.

• Bromination on toluene results in the substitution of one bromine atom on the aromatic ring, yielding bromotoluene.

The Grignard reaction on an aldehyde will produce a secondary alcohol.

• The Grignard reaction involves the addition of a Grignard reagent (organomagnesium compound) to an aldehyde or ketone.

• The reaction proceeds through the formation of a carbon-carbon bond.

• In the case of an aldehyde, the product will be a secondary alcohol.

• For example, the reaction of formaldehyde (HCHO) with a Grignard reagent such as methylmagnesium b...read more

Diastereomers and enantiomers are types of stereoisomers that differ in their spatial arrangement.

• Diastereomers are stereoisomers that have different configurations at one or more chiral centers but are not mirror images of each other.

• Enantiomers are stereoisomers that are non-superimposable mirror images of each other.

• Diastereomers have different physical and chemical properties, while enantiomers have identical physi...read more

The biaryl product can be synthesized through a variety of methods.

• One common method is the Suzuki-Miyaura cross-coupling reaction.

• Another method is the Buchwald-Hartwig amination reaction.

• Transition metal-catalyzed C-H activation can also be used.

• Examples of biaryl products include biphenyl and terphenyl.

The method for preparation of amide involves the reaction between a carboxylic acid and an amine.

• Amides can be prepared by the reaction of a carboxylic acid with an amine in the presence of a dehydrating agent.

• The reaction typically requires heating and can be catalyzed by an acid or base.

• The resulting product is an amide, which contains a carbonyl group bonded to a nitrogen atom.

• Example: The preparation of acetamide c...read more

The proton NMR peak of methyl aldehyde appears as a singlet at around 9-10 ppm.

• The proton NMR spectrum of methyl aldehyde shows a singlet peak.

• The chemical shift of the peak is typically around 9-10 ppm.

• The singlet peak indicates that the methyl aldehyde molecule has no neighboring protons.

Mass spectra of bromo chloro containing compound

• Bromo chloro compounds can have multiple isomers with different mass spectra

• The presence of bromine and chlorine atoms can cause fragmentation in the mass spectrum

• The mass spectrum can be used to determine the molecular weight and structural information of the compound