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2D Structure
Also known as: 2-methyl-1-propanol, Isobutyl alcohol, 2-methylpropan-1-ol, 78-83-1, 1-propanol, 2-methyl-, 1-hydroxymethylpropane
Molecular Formula
C4H10O
Molecular Weight
74.12  g/mol
InChI Key
ZXEKIIBDNHEJCQ-UHFFFAOYSA-N
FDA UNII
56F9Z98TEM

isobutanol is a metabolite found in or produced by Saccharomyces cerevisiae.
1 2D Structure

2D Structure

2 Identification
2.1 Computed Descriptors
2.1.1 IUPAC Name
2-methylpropan-1-ol
2.1.2 InChI
InChI=1S/C4H10O/c1-4(2)3-5/h4-5H,3H2,1-2H3
2.1.3 InChI Key
ZXEKIIBDNHEJCQ-UHFFFAOYSA-N
2.1.4 Canonical SMILES
CC(C)CO
2.2 Other Identifiers
2.2.1 UNII
56F9Z98TEM
2.3 Synonyms
2.3.1 MeSH Synonyms

1. 2-methyl-1-propanol

2. Isobutyl Alcohol

3. Isobutyl Alcohol, Aluminum Salt

4. Isobutyl Alcohol, Sodium Salt

5. Isobutyl Alcohol, Titanium (+4) Salt

2.3.2 Depositor-Supplied Synonyms

1. 2-methyl-1-propanol

2. Isobutyl Alcohol

3. 2-methylpropan-1-ol

4. 78-83-1

5. 1-propanol, 2-methyl-

6. 1-hydroxymethylpropane

7. Isopropylcarbinol

8. Iso-butyl Alcohol

9. 2-methylpropyl Alcohol

10. I-butyl Alcohol

11. Isobutylalkohol

12. 2-methylpropanol

13. Alcool Isobutylique

14. 2-methyl Propanol

15. Fermentation Butyl Alcohol

16. I-butanol

17. Rcra Waste Number U140

18. 2-methylpropanol-1

19. Fema No. 2179

20. Isopropyl Carbitol

21. Nsc 5708

22. Methyl-2 Propanol-1

23. Iso-c4h9oh

24. Mfcd00004740

25. 2-methyl-1-propanyl Alcohol

26. 56f9z98tem

27. Chebi:46645

28. Nsc-5708

29. Isobutylalkohol [czech]

30. Iso-butanol

31. Fema Number 2179

32. Isobutyl Alcohol (natural)

33. Isopropyl Carbinol

34. Alcool Isobutylique [french]

35. Hsdb 49

36. Ccris 2300

37. Einecs 201-148-0

38. Un1212

39. Alcohols, C8-13-iso-

40. Rcra Waste No. U140

41. Brn 1730878

42. Isobutylalcohol

43. Unii-56f9z98tem

44. Iso Butanol

45. Butanol-iso

46. Ai3-01777

47. 2-methylpropanoi

48. Ibuoh

49. 2-methyl-propanol

50. Iso-buoh

51. I-buoh

52. 2-methyl-l-propanol

53. 2-methyl-n-propanol

54. Isobutanol Acs Grade

55. Propanol, 2-methyl-

56. 2-methyl-propan-1-ol

57. Isobutanol, Hplc Grade

58. Dsstox_cid_1759

59. Ec 201-148-0

60. Dsstox_rid_76310

61. Isobutanol, Isobutyl Alcohol

62. Dsstox_gsid_21759

63. Isobutyl Alcohol Reagent Acs

64. 4-01-00-01588 (beilstein Handbook Reference)

65. Bidd:er0628

66. Isobutanol Or Isobutyl Alcohol

67. Isobutyl Alcohol [ii]

68. Isobutyl Alcohol [mi]

69. 2-methyl-1-propanol, 99%

70. Isobutyl Alcohol [fcc]

71. Natural Isobutyl Alcohol

72. Chembl269630

73. Isobutyl Alcohol [fhfi]

74. Isobutyl Alcohol [hsdb]

75. Dtxsid0021759

76. Wln: Q1y1&1

77. Isobutyl Alcohol [mart.]

78. Nsc5708

79. 2-methyl-1-propanol, 99.5%

80. Isobutyl Alcohol (fragrance Grade)

81. 2-methyl-1-propanol, Ar, 99%

82. Act03408

83. Isobutanol, Spectrophotometric Grade

84. Zinc1687155

85. Tox21_201214

86. Isobutyl Alcohol (isobutanol)

87. Lmfa05000100

88. Stl185664

89. 2-methyl-1-propanol(isobutyl Alcohol)

90. 2-methyl-1-propanol, Lr, >=99%

91. Akos000118740

92. Isobutyl Alcohol, >=99%, Fcc, Fg

93. Un 1212

94. 2-methyl-1-propanol [usp-rs]

95. Cas-78-83-1

96. Ncgc00091851-01

97. Ncgc00091851-02

98. Ncgc00258766-01

99. 2-methyl-1-propanol, Analytical Standard

100. 68989-27-5

101. 2-methyl-1-propanol, Anhydrous, 99.5%

102. 2-methyl-1-propanol, For Hplc, 99.5%

103. Isobutyl Alcohol, Acs Reagent, >=99.0%

104. Ft-0627343

105. I0094

106. Isobutyl Alcohol 5000 Microg/ml In Methanol

107. 2-methyl-1-propanol 10 Microg/ml In Methanol

108. Isobutyl Alcohol, Natural, >=99%, Fcc, Fg

109. 2-methyl-1-propanol 100 Microg/ml In Methanol

110. 2-methyl-1-propanol, Acs Reagent, >=99.0%

111. 2-methyl-1-propanol 1000 Microg/ml In Methanol

112. Q151797

113. 2-methyl-1-propanol, P.a., Acs Reagent, 99.0%

114. 2-methyl-1-propanol, Saj First Grade, >=99.0%

115. J-509912

116. 2-methyl-1-propanol, Jis Special Grade, >=99.0%

117. F0001-2058

118. Z955123524

119. 2-methyl-1-propanol, Acs Spectrophotometric Grade, >=99.0%

120. 2-methyl-1-propanol, Reag. Iso, 99%, Uv Hplc Spectroscopic

121. Isobutanol Or Isobutyl Alcohol [un1212] [flammable Liquid]

122. 2-methyl-1-propanol, Puriss. P.a., Acs Reagent, >=99.5% (gc)

123. 2-methyl-1-propanol, Bioultra, For Molecular Biology, >=99.5% (gc)

124. 2-methyl-1-propanol, United States Pharmacopeia (usp) Reference Standard

125. 2-methyl-1-propanol, Puriss. P.a., Acs Reagent, Reag. Ph. Eur., >=99% (gc)

126. 5oz

2.4 Create Date
2005-03-26
3 Chemical and Physical Properties
Molecular Weight 74.12 g/mol
Molecular Formula C4H10O
XLogP30.8
Hydrogen Bond Donor Count1
Hydrogen Bond Acceptor Count1
Rotatable Bond Count1
Exact Mass74.073164938 g/mol
Monoisotopic Mass74.073164938 g/mol
Topological Polar Surface Area20.2 Ų
Heavy Atom Count5
Formal Charge0
Complexity17.6
Isotope Atom Count0
Defined Atom Stereocenter Count0
Undefined Atom Stereocenter Count0
Defined Bond Stereocenter Count0
Undefined Bond Stereocenter Count0
Covalently Bonded Unit Count1
4 Drug and Medication Information
4.1 Minimum/Potential Fatal Human Dose

As extrapolated from rat data ... 3 to 7 oz represents reasonable est of single oral mean lethal dose of any butyl alcohol in man. /Alcohols, higher/

Gosselin, R.E., R.P. Smith, H.C. Hodge. Clinical Toxicology of Commercial Products. 5th ed. Baltimore: Williams and Wilkins, 1984., p. III-13


5 Pharmacology and Biochemistry
5.1 Absorption, Distribution and Excretion

Isobutyl alcohol is absorbed through the gastrointestinal tract, lungs, & skin.

Snyder, R. (ed.). Ethel Browning's Toxicity and Metabolism of Industrial Solvents. Second Edition. Volume 3 Alcohols and Esters. New York, NY: Elsevier, 1992., p. 48


Urine was analyzed immediately, 1, 2, 8, and 9 hr after drinking (during 2 hr) 3.75 mL/kg of beverages containing orange juice, 15 or 40% ethanol, and 1 g/L of 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol or a mixture of 1-propanol & isobutyl alcohol. Maximum urine levels /in mg/L/ were found 1 hr after drinking ended: 1-propanol 5.04, 2-propanol 3.36, 1-butanol 0.43, 2-butanol 2.55, isobutyl alcohol ... 1.7-2.03 mg/L. Urine treatment with beta-glucuronidase before analysis indicated that significant amounts of the alcohols were excreted as glucuronides, esp isobutyl alcohol. 2-Propanol and 2-butanol were the slowest to be metabolized. When mixtures of alcohols were given, the concentrations of isobutyl alcohol glucuronides were high with the mixtures containing 5 and 15% ethanol, and decreased at 40% ethanol.

Bonte W et al; Blutalkohol 18 (6): 412-26 (1981)


Twelve subjects were exposed to 300 or 600 mg/cu m of butyl alcohol in inspired air during rest and during exercise on a bicycle ergometer. Exposure lasted 2 hr. The arterial blood concentration was low. The concentration in the last part of the expired air, ie, the alveolar concentration, was low. The quotient of alveolar concentration was low in relation to the low percentage uptake. The high solubility of butyl alcohol in water may explain the results.

PMID:973129 Astrand I et al; Scand J Work Environ Health 2 (3): 165-75 (1976)


Isobutyl alcohol has been observed in the blood of humans who did not have clearly defined exposure to isobutyl alcohol sources.

PMID:934736 Dowty BJ et al; Pediatr Res 10: 696 (1976)


About 618 mg/kg isobutanol was administered by gavage to rabbits. After 24 hours, 4.4% of the dose was excreted as a glucuronic acid conjugate in the urine. Analysis of urinary or breath data suggested that a negligible fraction of orally administered isobutanol was excreted as unchanged isobutanol within 40 hours after administration to rabbits.

Kamil JA et al; Biochem J 53: 129-136 (1953) as cited in USEPA; Health and Environmental Effects Profile for Isobutyl alcohol p.vi (1986) ECAO-CIN-P171


5.2 Metabolism/Metabolites

Urine was analyzed immediately, 1, 2, 8, and 9 hr after drinking (during 2 hr) 3.75 mL/kg of beverages containing orange juice, 15 or 40% ethanol, and 1 g/L of 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol or a mixture of 1-propanol & isobutyl alcohol. Maximum urine levels /in mg/L/ were found 1 hr after drinking ended: 1-propanol 5.04, 2-propanol 3.36, 1-butanol 0.43, 2-butanol 2.55, isobutyl alcohol ... 1.7-2.03 mg/L. Urine treatment with beta-glucuronidase before analysis indicated that significant amounts of the alcohols were excreted as glucuronides, esp isobutyl alcohol. 2-Propanol and 2-butanol were the slowest to be metabolized. When mixtures of alcohols were given, the concentrations of isobutyl alcohol glucuronides were high with the mixtures containing 5 and 15% ethanol, and decreased at 40% ethanol.

Bonte W et al; Blutalkohol 18 (6): 412-26 (1981)


Isobutyl alcohol is conjugated by glucuronic acid to form the glucuronide. It is also metabolized to isobutyraldehyde & isovaleric acid.

Snyder, R. (ed.). Ethel Browning's Toxicity and Metabolism of Industrial Solvents. Second Edition. Volume 3 Alcohols and Esters. New York, NY: Elsevier, 1992., p. 49


Metabolism of ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, & tert-butanol were studied after oral admin in rabbits. Blood pH was on the acid side with propanol, butanol, & isobutanol, and on the alkaline side with isopropanol & sec-butanol, but no change was observed with ethanol & tert-butanol. Butanol & isobutanol had the lowest rate of urinary excretion. Acetaldehyde and acetic acid were detected as the urinary metabolites of ethanol and propanol, whereas isobutyraldehyde & isovaleric acid were the metabolites of isobutanol.

SAITO M; NICHIDAI IGAKU ZASSHI 34 (8-9): 569-85 (1975)


The hydroxylation of iso-butane led to the production of both t-butyl alcohol and iso-butyl alcohol by resting cell suspensions of methane grown Methylosinus trichorsporium 0B3b, at an optimum pH of 6-7, and an optimum temp of 40 C.

Hou CT et al; Dev and Microbiol 23: 477-82 (1982)


Isobutanol has known human metabolites that include (2S,3S,4S,5R)-3,4,5-trihydroxy-6-(2-methylpropoxy)oxane-2-carboxylic acid.

S73 | METXBIODB | Metabolite Reaction Database from BioTransformer | DOI:10.5281/zenodo.4056560


5.3 Mechanism of Action

The limited isobutanol tolerance of Escherichia coli is a major drawback during fermentative isobutanol production. Different from classical strain engineering approaches, this work was initiated to improve E. coli isobutanol tolerance from its transcriptional level by engineering its global transcription factor cAMP receptor protein (CRP). Random mutagenesis libraries were generated by error-prone PCR of crp, and the libraries were subjected to isobutanol stress for selection. Variant IB2 (S179P, H199R) was isolated and exhibited much better growth (0.18/hr) than the control (0.05/hr) in 1.2% (v/v) isobutanol (9.6g/L). Genome-wide DNA microarray analysis revealed that 58 and 308 genes in IB2 had differential expression (>2-fold, p< 0.05) in the absence and presence of 1% (v/v) isobutanol, respectively. When challenged with isobutanol, genes related to acid resistance (gadABCE, hdeABD), nitrate reduction (narUZYWV), flagella and fimbrial activity (lfhA, yehB, ycgR, fimCDF), and sulfate reduction and transportation (cysIJH, cysC, cysN) were the major functional groups that were up-regulated, whereas most of the down-regulated genes were enzyme (tnaA) and transporters (proVWX, manXYZ). As demonstrated by single-gene knockout experiments, gadX, nirB, rhaS, hdeB, and ybaS were found associated with strain isobutanol resistance. The intracellular reactive oxygen species (ROS) level in IB2 was only half of that of the control when facing stress, indicating that IB2 can withstand toxic isobutanol much better than the control.

PMID:24203355 Chong H et al; Biotechnol Bioeng. 111(4):700-8 (2014).


Escherichia coli has been engineered to produce isobutanol, with titers reaching greater than the toxicity level. However, the specific effects of isobutanol on the cell have never been fully understood. Here, /researchers/ aim to identify genotype-phenotype relationships in isobutanol response. An isobutanol-tolerant mutant was isolated with serial transfers. Using whole-genome sequencing followed by gene repair and knockout, /researchers/ identified five mutations (acrA, gatY, tnaA, yhbJ, and marCRAB) that were primarily responsible for the increased isobutanol tolerance. /They/ successfully reconstructed the tolerance phenotype by combining deletions of these five loci, and identified glucosamine-6-phosphate as an important metabolite for isobutanol tolerance, which presumably enhanced membrane synthesis. The isobutanol-tolerant mutants also show increased tolerance to n-butanol and 2-methyl-1-butanol, but showed no improvement in ethanol tolerance and higher sensitivity to hexane and chloramphenicol than the parental strain. These results suggest that C4, C5 alcohol stress impacts the cell differently compared with the general solvent or antibiotic stresses. Interestingly, improved isobutanol tolerance did not increase the final titer of isobutanol production.

PMID:21179021 Full text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3018172 Atsumi S et al; Mol Syst Biol. 6:449 (2010).