Benzyl alcohol is a simple aromatic primary alcohol (C7H8O) with a benzylic -CH2OH group that is widely used in pharmaceutical science. This concise, SEO-focused introduction highlights the benzyl alcohol structure, physical and chemical properties, common pharmaceutical uses (solvent, preservative, excipient), formulation considerations, spectroscopy, metabolism and safety concerns important for B.Pharm students preparing for exams and practical formulation work. Understanding its reactivity (oxidation to benzaldehyde/benzoic acid), analytical identification (IR, NMR, UV) and toxicology (neonatal risk) is essential for rational drug design and safe product development. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. What is the molecular formula of benzyl alcohol?
- C7H8O
- C6H6O
- C6H5OH
- C7H6O
Correct Answer: C7H8O
Q2. Which functional group is present in benzyl alcohol?
- Secondary alcohol
- Tertiary alcohol
- Primary (benzylic) alcohol
- Phenol
Correct Answer: Primary (benzylic) alcohol
Q3. How is the structure of benzyl alcohol best described?
- A benzene ring directly bonded to a hydroxyl group
- A benzene ring attached to a methylene bearing a hydroxyl group (C6H5CH2OH)
- A cyclohexanol derivative
- An alkyl alcohol with no aromatic ring
Correct Answer: A benzene ring attached to a methylene bearing a hydroxyl group (C6H5CH2OH)
Q4. What is the IUPAC name for benzyl alcohol?
- Benzenemethanol
- Benzyl hydroxide
- Phenyl ethanol
- Benzylate
Correct Answer: Benzenemethanol
Q5. What is the approximate molecular weight of benzyl alcohol?
- 108.14 g/mol
- 94.11 g/mol
- 122.17 g/mol
- 80.10 g/mol
Correct Answer: 108.14 g/mol
Q6. What is the approximate boiling point of benzyl alcohol at 1 atm?
- 78 °C
- 100 °C
- 205 °C
- 350 °C
Correct Answer: 205 °C
Q7. How soluble is benzyl alcohol in water?
- Highly soluble (completely miscible)
- Moderately soluble
- Practically insoluble
- Completely immiscible
Correct Answer: Moderately soluble
Q8. Which spectroscopic signal is diagnostic for the benzylic CH2 in 1H NMR of benzyl alcohol?
- ~1.2 ppm (triplet)
- ~3.5 ppm (broad)
- ~4.5 ppm (singlet/doublet depending on exchange)
- ~7.0 ppm (multiplet)
Correct Answer: ~4.5 ppm (singlet/doublet depending on exchange)
Q9. In IR spectroscopy which absorption indicates the presence of the hydroxyl group in benzyl alcohol?
- A sharp peak at ~1700 cm-1
- A broad band at ~3200–3600 cm-1
- Strong band at ~2200 cm-1
- Weak band at ~1500 cm-1
Correct Answer: A broad band at ~3200–3600 cm-1
Q10. What is the primary oxidative metabolite of benzyl alcohol in humans?
- Benzene
- Benzaldehyde
- Toluene
- Phenol
Correct Answer: Benzaldehyde
Q11. Which enzyme primarily oxidizes benzyl alcohol to benzaldehyde?
- Monoamine oxidase
- Alcohol dehydrogenase
- Aldolase
- Cytochrome P450 only
Correct Answer: Alcohol dehydrogenase
Q12. Benzyl alcohol is commonly used in pharmaceutical formulations as:
- An active antimicrobial API
- A solvent and preservative/excipient
- An inorganic buffer
- A suspension stabilizer only
Correct Answer: A solvent and preservative/excipient
Q13. Which of the following best describes benzyl alcohol’s antimicrobial action at low concentrations?
- Bactericidal by cell wall lysis
- Fungistatic only
- Bacteriostatic (inhibits bacterial growth)
- Antiviral by nucleic acid cleavage
Correct Answer: Bacteriostatic (inhibits bacterial growth)
Q14. Which oxidation product of benzyl alcohol is commonly formed under mild oxidation conditions (e.g., PCC)?
- Benzoic acid directly
- Benzaldehyde
- Toluene
- Phenylmethane
Correct Answer: Benzaldehyde
Q15. Which ester is formed by esterification of benzyl alcohol with benzoic acid?
- Benzyl acetate
- Benzyl benzoate
- Phenyl acetate
- Benzoic anhydride
Correct Answer: Benzyl benzoate
Q16. In organic synthesis, benzyl groups are often used as protecting groups for alcohols. What is the common protecting group abbreviation?
- TBDMS
- Bn
- Ac
- Tr
Correct Answer: Bn
Q17. Which reaction commonly converts benzyl alcohol to benzyl chloride?
- Nitration
- Reaction with HCl (substitution at benzylic carbon)
- Hydrogenation
- Ozonolysis
Correct Answer: Reaction with HCl (substitution at benzylic carbon)
Q18. Which property makes the benzylic hydrogen atoms more reactive than those on a simple alkyl chain?
- Inductive withdrawal by oxygen
- Resonance stabilization of the benzylic radical or carbocation by the aromatic ring
- High steric hindrance
- Lower electronegativity of carbon
Correct Answer: Resonance stabilization of the benzylic radical or carbocation by the aromatic ring
Q19. Which analytical technique is most useful to confirm the aromatic ring substitution pattern in benzyl derivatives?
- Polarimetry
- 1H NMR and 13C NMR spectroscopy
- Conductivity measurement
- Titration
Correct Answer: 1H NMR and 13C NMR spectroscopy
Q20. Which physical hazard classification is associated with benzyl alcohol in safety data sheets?
- Non-flammable and non-combustible
- Flammable liquid
- Explosive under normal conditions
- Inert gas
Correct Answer: Flammable liquid
Q21. Which of the following describes a major safety concern when using benzyl alcohol in neonatal or preterm infants?
- Renal stone formation
- Gasping syndrome due to immaturity of metabolic pathways
- Severe allergic dermatitis in all infants
- Induction of premature labor
Correct Answer: Gasping syndrome due to immaturity of metabolic pathways
Q22. Benzyl alcohol is commonly used as a co-solvent to improve solubility of poorly soluble drugs because it is:
- Highly polar and ionizable
- Aromatic and miscible with many organic solvents
- Completely water miscible
- Aqueous buffer with high ionic strength
Correct Answer: Aromatic and miscible with many organic solvents
Q23. Which storage recommendation is appropriate for benzyl alcohol to maintain stability?
- Store in direct sunlight at high temperature
- Store in a cool, dark place in a tightly closed container
- Keep in aqueous solution indefinitely at room temperature
- Store near strong oxidizers for stabilization
Correct Answer: Store in a cool, dark place in a tightly closed container
Q24. Which reagent is suitable to oxidize benzyl alcohol all the way to benzoic acid under strong conditions?
- Potassium permanganate (KMnO4)
- Sodium borohydride (NaBH4)
- Hydrogen in presence of Pd/C
- Tetrabutylammonium fluoride (TBAF)
Correct Answer: Potassium permanganate (KMnO4)
Q25. In UV spectrophotometry benzyl alcohol absorbs strongly due to:
- n→π* transition of the hydroxyl group only
- π→π* transitions of the aromatic ring around 254 nm
- Charge-transfer bands at 600 nm
- No UV absorption because it lacks conjugation
Correct Answer: π→π* transitions of the aromatic ring around 254 nm
Q26. Which of the following describes benzyl alcohol’s role in topical formulations?
- Used only as a sweetening agent
- Used as solvent, penetration enhancer, and mild local anesthetic/antipruritic
- Acts as a strong emulsifier
- Used as a bulk filler to increase tablet size
Correct Answer: Used as solvent, penetration enhancer, and mild local anesthetic/antipruritic
Q27. Which is a common impurity formed by oxidation of benzyl alcohol during storage?
- Benzoic acid and benzaldehyde
- Toluene and benzene
- Glycerol
- Acetic acid only
Correct Answer: Benzoic acid and benzaldehyde
Q28. Which statement about benzyl alcohol’s acidity is correct?
- It is a strong acid (pKa < 1)
- It behaves like a phenol (pKa ~10)
- Alcohols are weak acids; benzyl alcohol has a pKa around 16
- It is a strong base
Correct Answer: Alcohols are weak acids; benzyl alcohol has a pKa around 16
Q29. What happens when benzyl alcohol undergoes catalytic hydrogenation under typical conditions?
- The aromatic ring is readily hydrogenated to cyclohexane derivatives
- The benzylic alcohol is reduced to an alkane (no typical product under mild hydrogenation)
- It is inert to hydrogenation under mild conditions; aromatic ring requires harsher conditions
- It spontaneously polymerizes
Correct Answer: It is inert to hydrogenation under mild conditions; aromatic ring requires harsher conditions
Q30. Which formulation type commonly uses benzyl alcohol as a preservative or excipient?
- Single-use preservative-free injectables only
- Multi-dose parenteral vials and some topical solutions
- Metal implants
- Dry powder inhalers exclusively
Correct Answer: Multi-dose parenteral vials and some topical solutions
Q31. In mass spectrometry of benzyl alcohol, which fragment is commonly observed from cleavage at the benzylic position?
- Phenyl cation (C6H5+) or benzyl fragment
- Molecular oxygen radical
- Ammonium adduct only
- Unrelated polymeric ions only
Correct Answer: Phenyl cation (C6H5+) or benzyl fragment
Q32. Which of the following is a pharmacologically relevant derivative produced from benzyl alcohol metabolism before excretion?
- Benzoic acid conjugated to glycine (hippuric acid)
- Glucose conjugate only
- Sulfate conjugate exclusively
- Unchanged benzyl alcohol is excreted only
Correct Answer: Benzoic acid conjugated to glycine (hippuric acid)
Q33. Which statement is true regarding benzyl alcohol’s use in ophthalmic products?
- It is universally considered safe at any concentration for ophthalmic use
- It can be used as a preservative in some ophthalmic formulations but concentration and tolerance must be considered
- It is never used in eye formulations due to complete toxicity
- It is the only preservative permitted in ophthalmics
Correct Answer: It can be used as a preservative in some ophthalmic formulations but concentration and tolerance must be considered
Q34. Which structural change converts benzyl alcohol into a protecting benzyl ether?
- Oxidation of the hydroxyl to a carbonyl
- Conversion of the alcohol to an ether (R-O-CH2-Ph) by alkylation
- Hydrogenation of the aromatic ring
- Removal of the benzylic hydrogen only
Correct Answer: Conversion of the alcohol to an ether (R-O-CH2-Ph) by alkylation
Q35. Which of the following best explains why benzyl alcohol is a useful solvent for many APIs?
- It is highly acidic which solubilizes bases
- Its aromatic character and intermediate polarity dissolve a broad range of lipophilic and moderately polar compounds
- It forms ionic salts with most APIs to increase solubility
- It is miscible with water and can dissolve ionic salts readily
Correct Answer: Its aromatic character and intermediate polarity dissolve a broad range of lipophilic and moderately polar compounds
Q36. What is a common regulatory concern when selecting benzyl alcohol as a preservative for injectable products?
- Potential for causing gasping syndrome in neonates and dosing limits for vulnerable populations
- It is banned in all pharmaceuticals worldwide
- It forms stable complexes with all APIs, altering potency
- It spontaneously converts into formaldehyde in solution
Correct Answer: Potential for causing gasping syndrome in neonates and dosing limits for vulnerable populations
Q37. Which of the following statements about benzyl alcohol and acylation reactions is correct?
- Benzyl alcohol cannot form esters
- Benzyl alcohol readily forms esters with acid chlorides or carboxylic acids under appropriate conditions
- Benzyl alcohol is inert to acylation reagents
- Benzyl alcohol only forms amides, not esters
Correct Answer: Benzyl alcohol readily forms esters with acid chlorides or carboxylic acids under appropriate conditions
Q38. Which physical property distinguishes benzyl alcohol from simple aliphatic alcohols like ethanol?
- It is a gas at room temperature
- It contains an aromatic ring, increasing molecular weight and reducing volatility compared to ethanol
- It has higher water miscibility than ethanol
- It is ionic in aqueous solution
Correct Answer: It contains an aromatic ring, increasing molecular weight and reducing volatility compared to ethanol
Q39. Which statement about the acidity/basicity of benzyl alcohol is correct in formulation chemistry?
- Benzyl alcohol is strongly basic and frequently used to raise pH
- Benzyl alcohol is a weakly acidic alcohol and usually does not significantly change pH in formulations
- Benzyl alcohol is amphoteric and behaves like both a strong acid and base
- Benzyl alcohol will neutralize strong acids completely
Correct Answer: Benzyl alcohol is a weakly acidic alcohol and usually does not significantly change pH in formulations
Q40. What analytical approach is commonly used to quantify benzyl alcohol in pharmaceutical formulations?
- High-performance liquid chromatography (HPLC) or GC with appropriate detectors
- Gravimetric analysis only
- Titration with strong acid only
- Visual colorimetry without instrumentation
Correct Answer: High-performance liquid chromatography (HPLC) or GC with appropriate detectors
Q41. Which condition accelerates oxidative degradation of benzyl alcohol in storage?
- Storage under inert atmosphere in amber bottles
- Exposure to air, light and elevated temperature
- Frozen storage below -20 °C
- Storage in completely sealed, oxygen-free containers
Correct Answer: Exposure to air, light and elevated temperature
Q42. Which derivative of benzyl alcohol is widely used as a topical scabicide and insecticide?
- Benzyl acetate
- Benzyl benzoate
- Benzyl chloride
- Benzoic anhydride
Correct Answer: Benzyl benzoate
Q43. In synthetic organic chemistry, benzyl alcohol can be used to introduce which protecting group for carboxylic acids?
- Benzyl ester (–COOCH2Ph)
- Benzyl amide only
- Tert-butyldimethylsilyl ester
- Acetyl ester only
Correct Answer: Benzyl ester (–COOCH2Ph)
Q44. Which of the following best describes benzyl alcohol’s partition coefficient (log P) relative to water?
- Very high (log P > 5), extremely lipophilic
- Moderate lipophilicity (log P around 1–2)
- Highly hydrophilic (log P < -2)
- Completely insoluble in organic solvents
Correct Answer: Moderate lipophilicity (log P around 1–2)
Q45. Which chemical transformation readily converts benzyl alcohol into benzaldehyde under mild laboratory conditions?
- Reduction with LiAlH4
- Oxidation with PCC or mild oxidants
- Hydrogenation over Pd/C
- Reaction with ammonia
Correct Answer: Oxidation with PCC or mild oxidants
Q46. Which of the following describes a formulation consideration when using benzyl alcohol with proteins or peptides?
- Benzyl alcohol has no effect on protein stability
- Benzyl alcohol can denature some proteins or affect stability and must be compatibility-tested
- Benzyl alcohol universally stabilizes proteins at all concentrations
- Benzyl alcohol forms covalent bonds with peptide backbones stabilizing them
Correct Answer: Benzyl alcohol can denature some proteins or affect stability and must be compatibility-tested
Q47. Which degradation pathway is most relevant for benzyl alcohol under oxidative storage conditions?
- Hydrolysis to methane
- Oxidation to benzaldehyde and then to benzoic acid
- Nitration to form nitrobenzyl derivatives only
- Polymerization to high molecular weight polymers only
Correct Answer: Oxidation to benzaldehyde and then to benzoic acid
Q48. For analytical identification, which chromatographic detector is commonly paired with GC to detect benzyl alcohol?
- Refractive index detector
- Flame ionization detector (FID)
- Conductivity detector only
- Polarimeter
Correct Answer: Flame ionization detector (FID)
Q49. Which formulation population should be given special consideration or avoidance when benzyl alcohol-containing products are used?
- Healthy adults only
- Neonates and preterm infants
- All geriatric patients exclusively
- Only topical adult use is contraindicated
Correct Answer: Neonates and preterm infants
Q50. Which statement best summarizes why understanding benzyl alcohol structure and uses is important for B.Pharm students?
- Because it is an obscure compound with no pharmaceutical relevance
- Because its benzylic structure determines reactivity, formulation roles (solvent, preservative, excipient), analytical behavior and safety implications in drug products
- Because it replaces active pharmaceutical ingredients in most formulations
- Because it is a basic nutrient required in tablets
Correct Answer: Because its benzylic structure determines reactivity, formulation roles (solvent, preservative, excipient), analytical behavior and safety implications in drug products
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.
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