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Organic Chemistry Test

Description: This test contains 25 multiple choice on types of reagents.
Number of Questions: 25
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Tags: Phosphene Potentiator Potassium tert-butoxide etc. Types of Reagents Alkanes and Cycloalkanes Stereochemistry - I
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The reagent acting as a lachrymator is

  1. methanesulfonic acid

  2. methanesulfonic anhydride

  3. methanesulfonyl chloride

  4. methoxymethylenetriphenylphosphine


Correct Option: C
Explanation:

Methanesulfonyl chloride is a compound containing a sulfonyl chloride used to make methanesulfonates and to generate sulfene. It is highly toxic, moisture sensitive, corrosive and a lachrymator. It should be stored in a dry location, preferably in a desiccator.

Which of the following compounds is used as an industrial feedstock?

  1. Acetone

  2. Toluene

  3. Acrylamide

  4. Phenol


Correct Option: B
Explanation:

The pure and effective chemical, Toluene, is also known as methyl benzene. This aromatic hydrocarbon is widely used as a solvent and an industrial feedstock. Due to its intoxicating attributes, it is widely used as inhalant drug such as other solvents. Toluene is a clear water-insoluble liquid that smells like paint thinners.

Which of the following compounds is used as an environmentally benign cleaning agent?

  1. Methanol

  2. PG (Propylene Glycol)

  3. Citric Acid

  4. Ethyl Acetate


Correct Option: C
Explanation:

Citric Acid is widely known for its toxic elements and accurate composition. This anhydrous acts as a natural preservative, which is used to enhance sour or acidic taste in soft drinks and foods. Moreover, due to its varied properties, this acid is extensively used as an environmentally benign cleaning agent.

Caprolactam is the precursor of Nylon 6. Which of the following cycloalkanes acts as a raw material for the industrial production of caprolactam?

  1. Cyclopropane

  2. Cyclobutane

  3. Cyclopentane

  4. Cyclohexane


Correct Option: D
Explanation:

 Cyclohexane is a cycloalkane with the molecular formula C6H12. Cyclohexane is used as a non-polar solvent for the chemical industry, and also as a raw material for the industrial production of adipic acid and caprolactam, both of which are intermediates used in the production of nylon. On an industrial scale, cyclohexane is produced by reacting benzene with hydrogen.

Who synthesized indigo (a natural dye)?

  1. Marcellin Berthelot

  2. Friedrich August Kekule

  3. Adolf von Baeyer

  4. Markovnikov


Correct Option: C
Explanation:

Johann Friedrich Wilhelm Adolf von Baeyer was a German chemist who synthesized indigo. He was 1905th recipient of the Nobel Prize in Chemistry.

Which of the following is a component of jet fuel?

  1. Methylcyclopropane

  2. Methylcyclopentane

  3. Methylcyclohexane

  4. Methylcycloheptane


Correct Option: C
Explanation:

Methylcyclohexane is a colourless liquid with a faint benzene-like odour. Its molecular formula is C7H14. Methylcyclohexane is used in organic synthesis and it is also used as a solvent for cellulose ethers. It is a component of jet fuel and correction fluids.

The compound used in food products like cheeses & other baked products is

  1. butyl acetate

  2. 5-methacrylic acid

  3. mono ethylene glycol

  4. sorbitol


Correct Option: A
Explanation:

Butyl Acetate is widely used in different food products like cheese, candy ice- cream and baked products. However, this chemical is flammable in nature but it is smoke, flame and spark free. Butyl Acetate is a colourless chemical having characteristic odour, due to which it is highly demanded in diverse applications.

The isomerism, resulting from hindered rotation about single bonds, is

  1. atropisomers

  2. cis/trans- isomerism

  3. conformational isomerism

  4. optical isomerism


Correct Option: A
Explanation:

Atropisomers are stereoisomers resulting from hindered rotation about single bonds where the steric strain barrier to rotation is high enough to allow for the isolation of the conformers.

Which of the following isomers can be interconverted by rotations about single bonds?

  1. Diastereomers

  2. Racemic mixture

  3. Enantiomer

  4. Conformers


Correct Option: D
Explanation:

Conformational isomerism is a form of stereoisomerism in which the isomers can be interconverted exclusively by rotations about formally single bonds. Such isomers are generally referred to as conformational isomers or conformers and specifically as rotamers when they differ by rotation about only one single bond.

Which of the following conformations is regarded as the most accurate representations of cyclohexane rings?

  1. Twist-boat

  2. Half-chair

  3. Boat

  4. Chair


Correct Option: D
Explanation:

Chair conformations are the most accurate representations of how cyclohexane rings are actually oriented in space. They appropriately reflect the angles between the carbons in the ring and the positions of the groups on each carbon in the ring.

Which of the following reactions involves the allylic or benzylic bromination of hydrocarbons ?

  1. The Barton-McCombie deoxygenation

  2. The Wohl-Ziegler reaction

  3. The Hunsdiecker reaction

  4. The Dowd-Beckwith ring expansion reaction


Correct Option: B
Explanation:

The Wohl-Ziegler reaction is a chemical reaction that involves the allylic or benzylic bromination of hydrocarbons using an N-bromoimide and a radical initiator.

The reagent used to detect fingerprints is

  1. N-Methylmorpholine

  2. Ninhydrin

  3. Phosgene

  4. Phosphorus tribromide


Correct Option: B
Explanation:

Ninhydrin (2,2-Dihydroxyindane-1,3-dione) is a chemical used to detect ammonia or primary and secondary amines. Ninhydrin is most commonly used to detect fingerprints, as the terminal amines of lysine residues in peptides and proteins sloughed off in fingerprints react with ninhydrin.

The molecule lacking a stereogenic center shows ---------------------- chirality.

  1. planar

  2. axial

  3. supramolecular

  4. inherent


Correct Option: B
Explanation:

Axial chirality is a special case of chirality in which a molecule does not possess a stereogenic center (the most common form of chirality in organic compounds) but an axis of chirality - an axis about which a set of substituents is held in a spatial arrangement that is not superposable on its mirror image. Axial chirality is most commonly observed in atropisomeric biaryl compounds wherein the rotation about the aryl-aryl bond is restricted.

Zyklon A is a pesticide. Which among the following reagents acts as the active ingredient of Zyklon A?

  1. Methyl chloroformate

  2. Methyl cyanoformate

  3. Methyl methanesulfonate

  4. N-Methylmorpholine-N-oxide


Correct Option: B
Explanation:

Methyl cyanoformate is the organic compound with the formula CH3OC(O)CN. This colourless liquid is used as a reagent in organic synthesis as a source of the methoxycarbonyl group. It is also an active ingredient in the pesticide product Zyklon A. It is also known as Mander's reagent.

The reagent capable of transferring hydrides to metal centers is

  1. polymethylhydrosiloxane

  2. polydimethylsiloxane

  3. potassium bis(trimethylsilyl)amide

  4. potassium tert-butoxide


Correct Option: A
Explanation:

Polymethylhydrosiloxane (PMHS) is a polymer with the general structure -(CH3(H)Si-O)-. It is used in organic chemistry as a mild and stable reducing agent, easily transferring hydrides to metal centers.

The reagent used in the Oseltamivir total synthesis is

  1. trimethyl orthoformate

  2. trimethylsilyl azide

  3. trimethylsilyl chloride

  4. trimethylsilyldiazomethane


Correct Option: B
Explanation:

It is considered as a safer replacement for hydrazoic acid in many reactions. It will however over time hydrolyze to hydrogen azide and therefore it must be stored free of moisture. It is used in the Oseltamivir total synthesis.

The cyclic structure of monosaccharides is represented by

  1. Newman projection

  2. Fischer projection

  3. Haworth projection

  4. Natta projection


Correct Option: C
Explanation:

A Haworth projection is a common way of representing the cyclic structure of monosaccharides with a simple three-dimensional perspective.

Which of the following reagents is used in the methylenation of carbonyl compounds?

  1. Webster's reagent

  2. Woollins' reagent

  3. Nysted reagent

  4. Tebbe reagent


Correct Option: D
Explanation:

The Tebbe reagent is the organometallic compound. It is used in the methylenation of carbonyl compounds, which means that it converts organic compounds containing R2C=O group into the related R2C=CH2 derivative.

The effect hindering the bond rotation is

  1. the Gauche effect

  2. the beta-silicon effect

  3. an anomeric effect

  4. the Baker-Nathan effect


Correct Option: A
Explanation:

The Gauche effect characterizes any gauche rotamer which is actually more stable than the anti rotamer.This effect is present in 1,2-difluoroethane (H2FCCFH2) for which the gauche conformation is more stable by 2.4 to 3.4 kJ/mole in the gas phase. Another example is 1,2-dimethoxyethane. In stereochemistry, gauche interactions hinder bond rotation.

The reagent used in the oxidation of alkenes to epoxides is

  1. dansyl amide

  2. dansyl chloride

  3. diethylzinc

  4. dimethyldioxirane


Correct Option: D
Explanation:

Dimethyldioxirane (DMDO) is a dioxirane derived from acetone. The dioxirane is a reagent used in organic synthesis.The most common use of DMDO is the oxidation of alkenes to epoxides.

Among the following reagents, ---------------------- is used in the treatment of epoxy.

  1. 2,6-Di-tert-butylpyridine

  2. 1,5-Diazabicyclo[4.3.0]non-5-ene

  3. 1,8-Diazabicyclo[5.4.0]undec-7-ene

  4. 2,2-Dimethoxypropane


Correct Option: C
Explanation:

1,8-Diazabicyclo[5.4.0]undec-7-ene or DBU, is a chemical compound, which belongs to the class of amidine compounds. It is used in organic synthesis as a catalyst, complexing ligand and a strong (pKa = 24.34 in acetonitrile) non-nucleophilic base. It is used as a curing agent for epoxy and as a protecting agent for the synthesis of cephalosporin.

Which of the following is a quaternary ammonium salt ?

  1. Tetra-n-butylammonium fluoride

  2. Tetrabutylammonium tribromide

  3. Tetrakis(triphenylphosphine)palladium(0)

  4. Tetramethylazodicarboxamide


Correct Option: A
Explanation:

Tetra-n-butylammonium fluoride or TBAF is a quaternary ammonium salt .It is usually encountered in the latter form as a source of organic-soluble fluoride ion to remove silyl ether protecting groups. It is also used as a phase transfer catalyst and as a mild base.

Among the following -------------------- reagent acts as a catalyst in the production of polyurethane.

  1. Tetramethylguanidine

  2. 2,2,6,6-Tetramethylpiperidine

  3. 2,2,2-Trichlorethoxycarbonyl chloride

  4. 1,3-Propanedithiol


Correct Option: A
Explanation:

Tetramethylguanidine is a strong amine base with a higher pKa than typical amines, therefore it can be used where a higher pKa is needed and as a substitute for DBU, DBN. It is also used as a catalyst in the production of polyurethane.

In an organic synthesis-------------------- introduces acetate group to an alcohol.

  1. Triethyl orthoacetate

  2. Triethyl phosphonoacetate

  3. Triethyloxonium tetrafluoroborate

  4. Dimethyl malonate


Correct Option: A
Explanation:

Triethyl orthoacetate is the ethyl orthoester of acetic acid. It is also known as 1,1,1-triethoxyethane, and is an oily liquid with a colour that is anywhere from yellow to colourless. It is used in organic synthesis for the introduction of the acetate group to an alcohol. It is also used in the Johnson-Claisen rearrangement.

A lachrymator is a substance that irritates eyes and produces tears. Among the following ------------------------- is a powerful lachrymator.

  1. Chlorosulfuric acid

  2. Thioacetic acid

  3. Tribromoisocyanuric acid

  4. Trifluoromethanesulfonic acid


Correct Option: A
Explanation:

Chlorosulfuric acid is the inorganic compound with the formula HSO3Cl. It is also known as chlorosulfonic acid. It is a distillable, colourless liquid .It is a hygroscopic and a powerful lachrymator.

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