Structure and uses of cinnamaldehyde MCQs With Answer

Cinnamaldehyde structure and uses MCQs With Answer

Cinnamaldehyde, a principal constituent of cinnamon oil, is an alpha,beta-unsaturated aromatic aldehyde important in pharmaceutical sciences. B.Pharm students must understand its chemical structure, synthesis routes, physical properties, biological activities, analytical detection (GC-MS, HPLC), formulation challenges, metabolism and safety profile. This set of focused, keyword-rich MCQs covers structure, reactivity, pharmacology, formulation, analytical methods, derivatives and regulatory aspects to reinforce learning. Questions range from basic identification to deeper application and mechanism-based queries, ideal for exam preparation and practical understanding. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the IUPAC name of cinnamaldehyde?

• 3-Phenyl-2-propenal
• Phenylacetaldehyde
• Benzaldehyde
• Cinnamic acid

Correct Answer: 3-Phenyl-2-propenal

Q2. Which functional groups are present in cinnamaldehyde?

• Alcohol and ether
• Ketone and ester
• Alpha,beta-unsaturated aldehyde and aromatic ring
• Carboxylic acid and amine

Correct Answer: Alpha,beta-unsaturated aldehyde and aromatic ring

Q3. Cinnamaldehyde exhibits which type of conjugation?

• Conjugation between aromatic ring and aldehyde via a double bond
• No conjugation, isolated systems
• Conjugation between two carbonyls
• Conjugation only within aromatic ring

Correct Answer: Conjugation between aromatic ring and aldehyde via a double bond

Q4. Which natural source is richest in cinnamaldehyde?

• Rosemary oil
• Cinnamon bark oil (Cinnamomum verum/armandii)
• Mint oil
• Clove oil

Correct Answer: Cinnamon bark oil (Cinnamomum verum/armandii)

Q5. Which analytical technique is most commonly used to quantify cinnamaldehyde in essential oils?

• FTIR spectroscopy
• Gas chromatography coupled with mass spectrometry (GC-MS)
• Titration with sodium hydroxide
• Polarimetry

Correct Answer: Gas chromatography coupled with mass spectrometry (GC-MS)

Q6. Which reaction readily occurs at the aldehyde functional group of cinnamaldehyde?

• Aldol condensation and nucleophilic additions
• Diels–Alder reaction
• Friedel–Crafts acylation on the aldehyde carbon
• Pericyclic electrocyclization

Correct Answer: Aldol condensation and nucleophilic additions

Q7. Reduction of cinnamaldehyde with NaBH4 primarily yields which product?

• Cinnamic acid
• Cinnamyl alcohol
• Hydrocinnamaldehyde
• Styrene

Correct Answer: Cinnamyl alcohol

Q8. Oxidation of cinnamaldehyde typically produces which compound?

• Cinnamic acid
• Benzaldehyde
• Cinnamyl alcohol
• Toluene

Correct Answer: Cinnamic acid

Q9. Which property of cinnamaldehyde contributes to its antimicrobial activity?

• High aqueous solubility causing osmotic shock
• Electrophilic alpha,beta-unsaturated aldehyde that reacts with thiols
• High molecular weight blocking bacterial pores
• Acts as a surfactant disrupting lipid bilayers by itself

Correct Answer: Electrophilic alpha,beta-unsaturated aldehyde that reacts with thiols

Q10. Which regulatory status is commonly associated with cinnamaldehyde for food flavoring?

• Completely banned worldwide
• Generally Recognized As Safe (GRAS) for use as a flavoring agent in certain concentrations
• Classified as a prescription-only drug
• Restricted to topical pharmaceutical use only

Correct Answer: Generally Recognized As Safe (GRAS) for use as a flavoring agent in certain concentrations

Q11. In UV-Vis spectral analysis, cinnamaldehyde shows absorption due to which chromophore?

• Conjugated alpha,beta-unsaturated system
• Isolated aldehyde only
• Saturated alkane chain
• Only aromatic ring with no conjugation

Correct Answer: Conjugated alpha,beta-unsaturated system

Q12. Which solvent is commonly used to prepare standard solutions of cinnamaldehyde for GC analysis?

• Water
• Methanol or hexane depending on method
• Glycerol
• Tris buffer

Correct Answer: Methanol or hexane depending on method

Q13. Which metabolic pathway primarily converts cinnamaldehyde in the body?

• Reduction to cinnamyl alcohol followed by conjugation
• Direct glucuronidation of the aldehyde without modification
• Oxidation to benzaldehyde
• Cleavage to benzene and CO2

Correct Answer: Reduction to cinnamyl alcohol followed by conjugation

Q14. Which structural isomer of cinnamaldehyde differs only in double bond geometry?

• Para-cinnamaldehyde
• E- and Z- cinnamaldehyde (trans and cis isomers)
• Ortho-cinnamaldehyde
• Meta-cinnamaldehyde

Correct Answer: E- and Z- cinnamaldehyde (trans and cis isomers)

Q15. Cinnamaldehyde’s pungent odor is primarily due to which structural feature?

• Long saturated alkyl chain
• Aromatic ring conjugated to an unsaturated aldehyde
• Presence of amine functional group
• Presence of multiple hydroxyl groups

Correct Answer: Aromatic ring conjugated to an unsaturated aldehyde

Q16. In topical formulations, cinnamaldehyde is often limited because it can cause:

• Systemic anticoagulation
• Skin sensitization and irritation
• Excessive hydration
• Hypersalivation only

Correct Answer: Skin sensitization and irritation

Q17. A common synthetic route to cinnamaldehyde is the Knoevenagel or Perkin-type condensation between benzaldehyde and which reagent?

• Acetaldehyde under acid catalysis
• Acetic anhydride and acetaldehyde (Perkin reaction) or malonic derivatives
• Formaldehyde under base
• Ethyl acetate without base

Correct Answer: Acetic anhydride and acetaldehyde (Perkin reaction) or malonic derivatives

Q18. Which derivative lacks the aldehyde function but retains the conjugated double bond and ring?

• Cinnamic acid
• Benzaldehyde
• Cinnamyl chloride
• Phenylacetaldehyde

Correct Answer: Cinnamic acid

Q19. Which chromatographic detector provides structural confirmation when analyzing cinnamaldehyde?

• Flame ionization detector only
• Mass spectrometry (MS) coupled to GC
• Refractive index detector only
• Conductivity detector

Correct Answer: Mass spectrometry (MS) coupled to GC

Q20. Which assay is suitable to determine free aldehyde content of a cinnamaldehyde formulation?

• Chromotropic acid assay for aldehydes
• Bromothymol blue titration
• Lowry protein assay
• pH meter reading

Correct Answer: Chromotropic acid assay for aldehydes

Q21. Which property limits water-based formulation of cinnamaldehyde?

• High water miscibility
• Low aqueous solubility and volatility
• Excessive ionic charge
• High melting point

Correct Answer: Low aqueous solubility and volatility

Q22. Which antimicrobial mechanism is attributed to cinnamaldehyde against bacteria?

• Inhibition of DNA gyrase only
• Membrane damage and enzyme inactivation via covalent binding
• Acting as a competitive inhibitor of glucose transport only
• Neutral pH disturbance by buffering

Correct Answer: Membrane damage and enzyme inactivation via covalent binding

Q23. In quality control, which physical property is commonly measured for cinnamaldehyde samples?

• Optical rotation, boiling point, refractive index and density
• pH of the neat oil
• Melting enthalpy exclusively
• Color only

Correct Answer: Optical rotation, boiling point, refractive index and density

Q24. Which structural modification typically reduces cinnamaldehyde’s electrophilicity?

• Hydrogenation of the C=C bond (saturating the double bond)
• Oxidation to the acid
• Conversion to the aldehyde from alcohol
• Introduction of electron-withdrawing nitro group on ring

Correct Answer: Hydrogenation of the C=C bond (saturating the double bond)

Q25. Which spectroscopic evidence confirms the aldehyde group in cinnamaldehyde?

• Strong IR absorption near 1700 cm^-1 and aldehydic proton around 9-10 ppm in 1H NMR
• Absence of any 13C NMR signals
• Single peak at 3000 cm^-1 only
• Yellow color in visible spectrum

Correct Answer: Strong IR absorption near 1700 cm^-1 and aldehydic proton around 9-10 ppm in 1H NMR

Q26. Which safety precaution is most relevant when handling concentrated cinnamaldehyde in the lab?

• Use of fume hood and gloves due to irritant vapors and skin sensitization
• No precautions needed; it is non-toxic
• Only refrigeration is required
• Handling with bare hands to avoid adsorption

Correct Answer: Use of fume hood and gloves due to irritant vapors and skin sensitization

Q27. Which microbial test can evaluate cinnamaldehyde’s preservative efficacy in formulations?

• Preservative Efficacy Test (PET) or challenge test
• Thin layer chromatography
• Moisture sorption isotherm
• pH stability test only

Correct Answer: Preservative Efficacy Test (PET) or challenge test

Q28. Cinnamaldehyde can form Schiff bases with which type of biomolecule?

• Primary amines (e.g., amino groups on proteins)
• Ether linkages
• Aliphatic hydrocarbons without heteroatoms
• Fatty acid esters only

Correct Answer: Primary amines (e.g., amino groups on proteins)

Q29. Which derivative is obtained by hydrogenation of both the C=C and C=O in cinnamaldehyde?

• Cinnamic acid
• 3-Phenylpropanol (hydrocinnamyl alcohol)
• Styrene
• Benzaldehyde

Correct Answer: 3-Phenylpropanol (hydrocinnamyl alcohol)

Q30. Which statement about cinnamaldehyde’s photostability is correct?

• It is highly photostable and unaffected by light
• It can undergo photochemical reactions leading to degradation under UV
• Light converts it quantitatively to benzene
• It polymerizes only in the dark

Correct Answer: It can undergo photochemical reactions leading to degradation under UV

Q31. Which biological activity has been reported for cinnamaldehyde relevant to therapeutics?

• Antidiabetic, anti-inflammatory and antimicrobial activities
• Exclusive pro-arrhythmic effect
• Acts only as a sedative hypnotic
• No reported bioactivity

Correct Answer: Antidiabetic, anti-inflammatory and antimicrobial activities

Q32. Which formulation approach improves dispersion of cinnamaldehyde in aqueous solutions?

• Use of surfactants or encapsulation (liposomes, cyclodextrins, nanoemulsions)
• Adding strong acid to lower pH to 1
• Heating above 200°C in water
• Direct sparging with nitrogen only

Correct Answer: Use of surfactants or encapsulation (liposomes, cyclodextrins, nanoemulsions)

Q33. Which enzyme class can metabolize cinnamaldehyde to cinnamic acid?

• Aldehyde dehydrogenases (ALDH)
• Proteases
• Cellulases
• Reverse transcriptases

Correct Answer: Aldehyde dehydrogenases (ALDH)

Q34. Cinnamaldehyde’s mode of action as an insecticidal agent is primarily attributed to:

• Respiratory chain inhibition and neuronal disruption
• Acting as a nutrient for insects
• Only physical blocking of spiracles
• Chelation of essential metals in soil

Correct Answer: Respiratory chain inhibition and neuronal disruption

Q35. Which mass spectral fragment is characteristic for cinnamaldehyde?

• Molecular ion peak at m/z 132 and benzyl cation fragments
• Molecular ion at m/z 18 only
• Only a single fragment at m/z 50
• No detectable fragments

Correct Answer: Molecular ion peak at m/z 132 and benzyl cation fragments

Q36. For stability testing, which condition accelerates cinnamaldehyde degradation?

• Storage at low temperature in dark
• Exposure to heat, light and oxygen
• Packaging under inert gas
• Storage in airtight amber vials at 4°C

Correct Answer: Exposure to heat, light and oxygen

Q37. In structure-activity relationship (SAR), electron-donating substituents on the aromatic ring typically:

• Increase electrophilicity of the double bond
• Decrease reactivity toward nucleophiles by stabilizing the conjugated system
• Have no effect on biological activity
• Convert cinnamaldehyde into an alkyne

Correct Answer: Decrease reactivity toward nucleophiles by stabilizing the conjugated system

Q38. Which preservative role can cinnamaldehyde play in pharmaceutical formulations?

• Antioxidant only
• Antimicrobial preservative to inhibit bacterial and fungal growth
• It cannot act as preservative under any conditions
• Only as a pH adjuster

Correct Answer: Antimicrobial preservative to inhibit bacterial and fungal growth

Q39. Which reaction will add across the C=C of cinnamaldehyde in a Michael addition?

• Nucleophiles such as thiols or amines adding to the beta-carbon
• Only radical halogenation at the aromatic ring
• Hydrolysis to release CO2
• SN1 substitution at the aldehyde carbon

Correct Answer: Nucleophiles such as thiols or amines adding to the beta-carbon

Q40. Which solvent system is preferred for HPLC analysis of cinnamaldehyde?

• Non-polar hexane only for reversed-phase HPLC
• Reversed-phase solvents like acetonitrile–water with acid modifier
• Pure water with no organic modifier
• Concentrated sulfuric acid

Correct Answer: Reversed-phase solvents like acetonitrile–water with acid modifier

Q41. Which property of cinnamaldehyde allows its use as a flavoring and fragrance agent?

• Highly pungent aromatic odor and volatility at room temperature
• Complete odorlessness
• No volatility and odorless solid form
• Strong metallic taste

Correct Answer: Highly pungent aromatic odor and volatility at room temperature

Q42. Which technique helps reduce the volatility and irritation potential of cinnamaldehyde in topical products?

• Formulation into encapsulated systems or using complexing agents such as cyclodextrins
• Increasing free cinnamaldehyde concentration
• Storing product at high temperatures
• Removing all excipients to maintain purity

Correct Answer: Formulation into encapsulated systems or using complexing agents such as cyclodextrins

Q43. Which pharmacokinetic property is expected for cinnamaldehyde due to its lipophilicity?

• Poor membrane permeability
• High membrane permeability and potential distribution into fatty tissues
• Complete confinement to plasma water
• Excretion unchanged in urine exclusively

Correct Answer: High membrane permeability and potential distribution into fatty tissues

Q44. Which chemical test distinguishes aldehydes like cinnamaldehyde from ketones?

• Tollens’ test or Schiff’s reagent giving a positive aldehyde response
• Benedict’s test specific for ketones
• Ninhydrin test for aldehydes only
• Karl Fischer titration

Correct Answer: Tollens’ test or Schiff’s reagent giving a positive aldehyde response

Q45. Which structural change would most likely increase aqueous solubility of cinnamaldehyde?

• Introducing a polar hydroxyl or carboxyl group on the aromatic ring
• Adding a long hydrophobic alkyl chain
• Hydrogenating the ring to cyclohexane
• Increasing molecular weight by polymerization

Correct Answer: Introducing a polar hydroxyl or carboxyl group on the aromatic ring

Q46. Which derivative is commonly produced when cinnamaldehyde reacts with sodium bisulfite?

• Bisulfite adduct (sulfite addition product) at the aldehyde carbon
• Formation of benzene sulfonic acid
• Complete fragmentation to phenylalanine
• Conversion to a ketone

Correct Answer: Bisulfite adduct (sulfite addition product) at the aldehyde carbon

Q47. Which microbiological application uses cinnamaldehyde as an active component?

• As an antifungal agent in agricultural formulations
• As a nutrient supplement for yeast cultures
• Only as an antiviral vaccine adjuvant
• No microbiological applications reported

Correct Answer: As an antifungal agent in agricultural formulations

Q48. Which chemical property explains cinnamaldehyde’s reactivity with cellular nucleophiles?

• Its saturated alkane backbone
• Electrophilic beta-carbon in the alpha,beta-unsaturated aldehyde enabling Michael addition
• Inertness due to aromatic stabilization only
• Strong basicity promoting deprotonation of proteins

Correct Answer: Electrophilic beta-carbon in the alpha,beta-unsaturated aldehyde enabling Michael addition

Q49. Which technique would you use to confirm the geometry (E/Z) of the double bond in cinnamaldehyde?

• 1H NMR coupling constants and NOE experiments
• Simple pH measurement
• Polarimetry alone
• Mass balance by weighing

Correct Answer: 1H NMR coupling constants and NOE experiments

Q50. Which formulation consideration is essential when including cinnamaldehyde in oral preparations?

• Masking flavor, controlling dose to avoid irritation, and ensuring stability
• Adding high concentrations to ensure strong irritation
• Eliminating all excipients to keep it pure
• Using only basic pH above 13

Correct Answer: Masking flavor, controlling dose to avoid irritation, and ensuring stability

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com