Bertrand's rule

Bertrand's rule

[′ber‚tränz ‚rül] (microbiology) The rule stating that in those compounds, and only in those compounds, having cis secondary alcoholic groups containing at least one carbon atom ofDconfiguration which is subtended by a primary alcohol group, or having a methyl-substituted primary alcohol group ofDconfiguration, theD-carbon atom will be dehydrogenated by the vinegar bacteria Acetobacter suboxydans, yielding a ketone.