Structure and uses of chlorobutanol MCQs With Answer

Structure and uses of chlorobutanol MCQs With Answer — Chlorobutanol is a tertiary alcohol bearing a trichloromethyl group, widely used as a preservative and mild local anesthetic in pharmaceutical formulations. This concise introduction covers chemical structure, physicochemical properties, stability, mechanism of antimicrobial action, formulation compatibility, analytical assays, and safety considerations relevant to B. Pharm students. Understanding chlorobutanol’s solubility, pH-dependent stability and typical usage concentrations (often 0.5% w/v) is essential for designing sterile ophthalmic, parenteral and topical products. These MCQs emphasize both theory and formulation practice to prepare you for exams and practical formulation challenges. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the commonly cited IUPAC name for chlorobutanol?

• 2-Chloro-2-butanol
• 1,1,1-Trichloro-2-methylpropan-2-ol
• 2-Methyl-2-butanol
• 1-Chloro-3-butanol

Correct Answer: 1,1,1-Trichloro-2-methylpropan-2-ol

Q2. What is the primary functional group present in chlorobutanol?

• Primary alcohol
• Secondary alcohol
• Tertiary alcohol
• Aldehyde

Correct Answer: Tertiary alcohol

Q3. Which structural fragment is characteristic of chlorobutanol?

• Phenyl ring
• Trichloromethyl group (CCl3)
• Nitro group
• Carboxylic acid

Correct Answer: Trichloromethyl group (CCl3)

Q4. What is the molecular formula of chlorobutanol?

• C4H7Cl3O
• C4H9ClO
• C5H9Cl3O
• C3H5Cl3O

Correct Answer: C4H7Cl3O

Q5. Which property best describes chlorobutanol’s solubility?

• Highly soluble in water and insoluble in alcohol
• Slightly soluble in water, freely soluble in alcohol and ether
• Completely insoluble in organic solvents
• Only soluble in strong acids

Correct Answer: Slightly soluble in water, freely soluble in alcohol and ether

Q6. What is a principal pharmaceutical use of chlorobutanol?

• Systemic analgesic
• Preservative in ophthalmic and parenteral formulations
• Antihypertensive agent
• Anticoagulant in blood products

Correct Answer: Preservative in ophthalmic and parenteral formulations

Q7. At which typical concentration is chlorobutanol commonly used as a preservative in ophthalmic preparations?

• 0.005% w/v
• 0.05% w/v
• 0.5% w/v
• 5% w/v

Correct Answer: 0.5% w/v

Q8. What additional pharmacological action does chlorobutanol exhibit besides preservative effect?

• Local anesthetic effect
• Beta-blocking activity
• Enzyme induction
• Prostaglandin synthesis

Correct Answer: Local anesthetic effect

Q9. Which microorganisms are effectively inhibited by chlorobutanol?

• Only gram-negative bacteria
• Bacteria and fungi, limited antiviral activity
• Only viruses
• Only mycobacteria

Correct Answer: Bacteria and fungi, limited antiviral activity

Q10. Which analytical technique is commonly used for quantitative assay of chlorobutanol in formulations?

• Atomic absorption spectroscopy
• Gas chromatography (GC)
• Colorimetric test for sulfates
• Kjeldahl nitrogen analysis

Correct Answer: Gas chromatography (GC)

Q11. Which statement about chlorobutanol stability is correct?

• Stable at all pH values
• More stable in acidic to neutral pH, hydrolyses under alkaline conditions
• Only stable in strong alkaline solutions
• Instantly decomposes in alcohol

Correct Answer: More stable in acidic to neutral pH, hydrolyses under alkaline conditions

Q12. Which excipient type enhances chlorobutanol solubility in aqueous systems?

• Hydrophobic oils
• Cosolvents such as ethanol or propylene glycol
• Strong bases
• Ion exchange resins

Correct Answer: Cosolvents such as ethanol or propylene glycol

Q13. Which USP/BP test property is commonly evaluated for chlorobutanol in pharmacopeial monographs?

• pH titration only
• Identification and assay (e.g., GC) and purity limits
• Viscosity measurement only
• Colorimetric carbohydrate test

Correct Answer: Identification and assay (e.g., GC) and purity limits

Q14. Which structural feature explains chlorobutanol’s weak acidity compared to primary alcohols?

• Presence of an aromatic ring
• Tertiary alcohol structure with electron-withdrawing trichloromethyl group
• Conjugated double bond
• Nitro substitution

Correct Answer: Tertiary alcohol structure with electron-withdrawing trichloromethyl group

Q15. Which safety concern is most relevant for chlorobutanol handling in the lab?

• Explosive peroxide formation
• CNS depressant effects and potential irritation—use gloves and work in fume hood
• Highly radioactive emissions
• Spontaneous combustion on air exposure

Correct Answer: CNS depressant effects and potential irritation—use gloves and work in fume hood

Q16. Which formulation type commonly avoids chlorobutanol as a preservative due to incompatibility or instability?

• Acidic ophthalmic drops
• Lyophilized parenteral powders reconstituted with alkaline diluent
• Topical creams with alcohol co-solvent
• Multi-dose aqueous nasal sprays at neutral pH

Correct Answer: Lyophilized parenteral powders reconstituted with alkaline diluent

Q17. How does chlorobutanol exert antimicrobial action?

• Specific enzyme inhibition of DNA gyrase only
• Protein denaturation and membrane disruption leading to broad nonspecific activity
• Acting as an oxidizing agent
• Chelation of divalent cations essential for microbes

Correct Answer: Protein denaturation and membrane disruption leading to broad nonspecific activity

Q18. Which physical state is chlorobutanol at room temperature in its anhydrous form?

• Gas
• Volatile liquid only
• White crystalline solid
• Highly viscous syrup

Correct Answer: White crystalline solid

Q19. Which solvent would you select to prepare a concentrated stock solution of chlorobutanol for formulation work?

• Pure water
• Ethyl alcohol (ethanol) or propylene glycol
• Strong aqueous base
• Concentrated hydrochloric acid

Correct Answer: Ethyl alcohol (ethanol) or propylene glycol

Q20. Which statement about chlorobutanol’s use in pediatrics/infants is most appropriate?

• It is always safe in any concentration for neonates
• Use caution—neonates are more sensitive to systemic absorption and CNS depression
• It is a nutrient and safe at high doses
• It is contraindicated in all age groups

Correct Answer: Use caution—neonates are more sensitive to systemic absorption and CNS depression

Q21. Which degradation concern may occur when chlorobutanol is stored in aqueous solutions for prolonged periods?

• Hydrolysis to inactive products and possible formation of acidic or volatile impurities
• Polymerization to high molecular weight chains
• Becoming more potent preservative over time
• Complete conversion to glucose

Correct Answer: Hydrolysis to inactive products and possible formation of acidic or volatile impurities

Q22. For multi-dose ophthalmic products, why is chlorobutanol sometimes chosen over benzalkonium chloride?

• Chlorobutanol is non-irritant at all concentrations
• It offers both preservative and mild local anesthetic action and may be preferred when QAS incompatibilities are a concern
• It is cheaper and more effective against all viruses
• It binds strongly to ocular tissues for prolonged release

Correct Answer: It offers both preservative and mild local anesthetic action and may be preferred when QAS incompatibilities are a concern

Q23. Which quality control parameter is critical when chlorobutanol is used in parenteral formulations?

• Conductivity only
• Sterility, preservative efficacy and assay for content and impurities
• Color only
• Particle size distribution only

Correct Answer: Sterility, preservative efficacy and assay for content and impurities

Q24. Which analytical detector is most suitable when using GC to detect chlorobutanol?

• Refractive index detector
• Flame ionization detector (FID)
• Polarimeter
• Conductivity detector

Correct Answer: Flame ionization detector (FID)

Q25. Which pH range generally favors stability of chlorobutanol in solution?

• Highly alkaline (pH > 11)
• Neutral to slightly acidic (pH 3–7)
• pH exactly 9.5
• Purely alkaline pH only

Correct Answer: Neutral to slightly acidic (pH 3–7)

Q26. What type of chemical reaction is primarily responsible for chlorobutanol decomposition in alkaline media?

• Oxidative polymerization
• Hydrolysis and cleavage of labile bonds
• Nitrosation
• Photosensitized dimerization

Correct Answer: Hydrolysis and cleavage of labile bonds

Q27. Which of the following is a reason to avoid chlorobutanol in protein-containing formulations?

• Enhances protein stability
• May denature proteins and reduce biological activity
• Forms beneficial covalent bonds with proteins
• Acts as a nutrient for proteins

Correct Answer: May denature proteins and reduce biological activity

Q28. Which packaging condition helps maintain chlorobutanol stability in an aqueous product?

• Exposure to light and high temperature
• Protected from light, stored at controlled cool temperature
• Open to air at room temperature
• Stored in alkaline glass containers

Correct Answer: Protected from light, stored at controlled cool temperature

Q29. Which regulatory consideration applies when using chlorobutanol in ophthalmic products?

• No need to declare preservative on label
• Concentration limits and preservative efficacy testing must comply with pharmacopeial/regulatory standards
• It is banned worldwide
• It requires a GMP exemption

Correct Answer: Concentration limits and preservative efficacy testing must comply with pharmacopeial/regulatory standards

Q30. Which of the following best describes chlorobutanol’s volatility and handling during analysis?

• Non-volatile—unsuitable for GC
• Relatively volatile and amenable to GC analysis after appropriate sample prep
• Explosive vapor at room temperature
• Completely immobile in headspace analysis

Correct Answer: Relatively volatile and amenable to GC analysis after appropriate sample prep

Q31. In combination with other preservatives, chlorobutanol is often:

• Never combined due to antagonism
• Used carefully to achieve broad-spectrum preservation and reduce irritancy
• Always combined with oxidizing agents
• Used only with heavy metals

Correct Answer: Used carefully to achieve broad-spectrum preservation and reduce irritancy

Q32. Which contraindication is most relevant for chlorobutanol-containing eye drops?

• History of allergy or sensitivity to chlorinated alcohols
• Hypertension
• Hypercholesterolemia
• Fracture healing impairment

Correct Answer: History of allergy or sensitivity to chlorinated alcohols

Q33. Which factor increases the antimicrobial effectiveness of chlorobutanol in a formulation?

• Lowering concentration below MIC
• Optimal pH, presence of cosolvent and correct concentration
• Dilution with large volumes of water only
• Increasing presence of proteins and lipids

Correct Answer: Optimal pH, presence of cosolvent and correct concentration

Q34. Which excipient class is most likely to inactivate chlorobutanol?

• Nonionic surfactants
• Strong bases or reducing agents that promote hydrolysis
• Polyols like glycerin
• Buffered saline at pH 7

Correct Answer: Strong bases or reducing agents that promote hydrolysis

Q35. Which statement about chlorobutanol and microbial resistance is accurate?

• Microbes never develop tolerance to chlorobutanol
• Prolonged sublethal exposure can select for tolerant strains; proper preservative challenge testing is needed
• It always increases microbial virulence
• Resistance develops through plasmid-encoded enzymes only

Correct Answer: Prolonged sublethal exposure can select for tolerant strains; proper preservative challenge testing is needed

Q36. Which preparation method is suitable for incorporating chlorobutanol into an aqueous eye drop?

• Add as a solid at room temperature without stirring
• Dissolve in a suitable cosolvent (ethanol or propylene glycol) before dilution into aqueous phase
• Neutralize with strong base first
• Heat to 150°C to dissolve

Correct Answer: Dissolve in a suitable cosolvent (ethanol or propylene glycol) before dilution into aqueous phase

Q37. Which microbial efficacy test is commonly used to confirm preservative effectiveness of chlorobutanol in a formulation?

• Preservative efficacy test (PET) / challenge test
• Acid value determination
• Gel permeation chromatography
• Osmolarity testing only

Correct Answer: Preservative efficacy test (PET) / challenge test

Q38. Which precaution is important when storing bulk chlorobutanol powder in the laboratory?

• Store in open container at high humidity
• Store in tightly closed container, cool, dry, away from light
• Store in direct sunlight to maintain potency
• Store with peroxides to stabilize

Correct Answer: Store in tightly closed container, cool, dry, away from light

Q39. Chlorobutanol is least effective against which class of pathogens?

• Gram-positive bacteria
• Fungi
• Non-enveloped viruses—generally more resistant to many chemical preservatives
• Gram-negative bacteria

Correct Answer: Non-enveloped viruses—generally more resistant to many chemical preservatives

Q40. Which effect would increasing temperature have on chlorobutanol-containing formulations?

• Promote degradation and reduce preservative potency
• Make it indefinitely stable
• Eliminate need for preservative testing
• Increase solubility without affecting stability

Correct Answer: Promote degradation and reduce preservative potency

Q41. Which formulation attribute could reduce available free chlorobutanol and lower preservative activity?

• High proportion of free water
• High protein, lipid or other organic load that sequesters preservative
• Low drug solubility
• Clear, buffered solution at pH 6

Correct Answer: High protein, lipid or other organic load that sequesters preservative

Q42. Which clinical sign is most likely with accidental ingestion of large amounts of chlorobutanol?

• CNS depression, lethargy and possible respiratory depression
• Severe hypertension
• Profuse salivation with stimulant effects
• Hyperactivity and seizures only

Correct Answer: CNS depression, lethargy and possible respiratory depression

Q43. Which feature of chlorobutanol’s chemical structure contributes to its lipophilicity?

• Hydroxyl group only
• Trichloromethyl group increases lipophilicity
• Multiple primary amines
• Aromatic heterocycles

Correct Answer: Trichloromethyl group increases lipophilicity

Q44. When performing assay of chlorobutanol by GC, what internal standard property is desirable?

• Completely reactive with chlorobutanol
• Chemically inert, similar volatility, and not present in sample
• Highly polar and non-volatile
• Identical retention time to chlorobutanol

Correct Answer: Chemically inert, similar volatility, and not present in sample

Q45. Which alternative preservative might be chosen if chlorobutanol is unsuitable due to instability?

• Benzalkonium chloride or phenoxyethanol depending on formulation compatibility
• Sucrose
• Sodium chloride only
• Distilled water

Correct Answer: Benzalkonium chloride or phenoxyethanol depending on formulation compatibility

Q46. Which regulatory test would detect microbial growth in a product containing chlorobutanol?

• Sterility test and preservative efficacy (challenge) test
• pH meter only
• Color comparison chart
• Viscosity only

Correct Answer: Sterility test and preservative efficacy (challenge) test

Q47. Which statement about odor and taste of chlorobutanol is correct?

• It is completely odorless and tasteless
• Has a slight camphor-like odor and bitter taste—relevant for ocular/topical use
• Smells like fresh citrus and is sweet
• Has pungent sulfur smell only

Correct Answer: Has a slight camphor-like odor and bitter taste—relevant for ocular/topical use

Q48. What precaution is important when combining chlorobutanol with proteins in biological formulations?

• No precaution—always stable
• Assess potential protein denaturation and conduct activity assays after addition
• Only increase temperature to stabilize
• Add heavy metals to prevent denaturation

Correct Answer: Assess potential protein denaturation and conduct activity assays after addition

Q49. Which environmental condition can accelerate chlorobutanol loss from topical formulations?

• Storage at low temperature
• High temperature and exposure to light
• Storage under inert atmosphere
• Maintaining refrigerated storage

Correct Answer: High temperature and exposure to light

Q50. For exam-oriented conceptual understanding, which two aspects best summarize chlorobutanol’s relevance in B. Pharm?

• Only its melting point and color
• Chemical structure (tertiary alcohol with trichloromethyl group) and practical uses as preservative/local anesthetic with formulation and stability considerations
• Its nutritional value and protein content
• Only its market price and vendor list

Correct Answer: Chemical structure (tertiary alcohol with trichloromethyl group) and practical uses as preservative/local anesthetic with formulation and stability considerations

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