LACTOBACILLIC ACID 



in the 9,10 and 11,12 positions were considered likely be- 

 cause of their relation to the monoethenoid fatty acids (9- 

 octadecenoic and 11-octadecenoic acids) which occur in bac- 

 terial lipids. If we consider the stereochemistry of this type 

 of molecule, it is apparent that each position isomeric 

 cyclopropane fatty acid can occur in four stereoisomeric 

 forms, two of which belong to the cis, the other to the trans 

 series. These forms are illustrated for the 9,10-compounds 

 in Fig. 1.5. 



In order to have available model compounds for compari- 



trans 



(CH2)7 



COOH 



(CH2)7 



COOH 



-^ Asymmetric carbon atoms 

 Fig. 1.5. The stereochemistry of 9,10 methyleneoctadecanoic acid. 



