Title:  Thiolactic Acid 
CAS Registry Number:  79-42-5 
CAS Name:  2-Mercaptopropanoic acid 
Additional Names:  2-mercaptopropionic acid;  2-thiolpropionic acid;  a-mercaptopropanoic acid 
Molecular Formula:  C3H6O2S 
Molecular Weight:  106.14 
Percent Composition:  C 33.95%, H 5.70%, O 30.15%, S 30.21% 
Line Formula:  CH3CH(SH)COOH 
Literature References:  First prepd from a-chloropropionic acid and potassium hydrosulfide:  Schacht, Ann. 129, 3 (1864); prepn from a-chloropropionic acid and sodium thiosulfate:  Martin, US 2413361 (1946 to Martin Labs).  From sodium sulfide, sulfur and a-bromopropionic acid:  Dumesnil, US 2985557 (1961 to Frank E. Jonas).  Review:  Reid, Organic Chemistry of Bivalent Sulfur vol. I (Chemical Publ. Co., New York, 1958) p 449. 
Properties:  Oil, disagreeable odor.  Solidif on cooling, crystals mp about 10°.  d415 1.220.  bp16 117°.  nD16 1.4823.  Miscible with water, alcohol, ether, acetone. 
Melting point:  mp about 10° 
Boiling point:  bp16 117° 
Index of refraction:  nD16 1.4823 
Density:  d415 1.220 
  
Derivative Type:  Copper salt  
Molecular Formula:  C3H5CuO2S 
Molecular Weight:  168.68 
Percent Composition:  C 21.36%, H 2.99%, Cu 37.67%, O 18.97%, S 19.01% 
Properties:  Yellow precipitate.  Practically insol in water and in dil HNO3. 
  
Derivative Type:  Barium salt  
Molecular Formula:  Ba(C3H5O2S)2 
Molecular Weight:  347.60 
Percent Composition:  Ba 39.51%, C 20.73%, H 2.90%, O 18.41%, S 18.45% 
Properties:  Rubbery compd, very sol in water.  Practically insol in alcohol. 
  
Derivative Type:  Mercury salt  
Molecular Formula:  Hg(C3H5O2S)2 
Molecular Weight:  410.86 
Percent Composition:  Hg 48.82%, C 17.54%, H 2.45%, O 15.58%, S 15.61% 
Properties:  Small shiny platelets, sparingly sol in water, very sol in alcohol. 
  
Derivative Type:  Sodium salt pentahydrate  
Molecular Formula:  C3H5NaO2S.5H2O 
Molecular Weight:  218.20 
Percent Composition:  C 16.51%, H 6.93%, Na 10.54%, O 51.33%, S 14.70% 
Properties:  Crystals.  Dec about 250°.  Sol in water, methanol, ethanol.  Less sol in propanol. 
  
Derivative Type:  Calcium salt decahydrate  
Molecular Formula:  Ca(C3H5O2S)2.10H2O 
Molecular Weight:  430.50 
Percent Composition:  Ca 9.31%, C 16.74%, H 7.02%, O 52.03%, S 14.90% 
Properties:  Crystals.  Dec 270°.  Sol in water, methanol, ethanol.  Less sol in propanol. 
  
Derivative Type:  Platinum salt  
Molecular Formula:  Pt(C3H5O2S)2 
Molecular Weight:  405.36 
Percent Composition:  Pt 48.13%, C 17.78%, H 2.49%, O 15.79%, S 15.82% 
Properties:  Greenish-yellow precipitate.  Practically insol in water and dil acids.  Sol in sodium hydroxide and sodium carbonate. 
  
Derivative Type:  Silver salt  
Molecular Formula:  C3H5AgO2S 
Molecular Weight:  213.00 
Percent Composition:  C 16.92%, H 2.37%, Ag 50.64%, O 15.02%, S 15.05% 
Properties:  Yellow precipitate.  Practically insol in water and dil HNO3. 
  
Use:  In depilatory and hair waving prepns.   |