A process for augmenting or enhancing the aroma of a perfume composition or cologne comprising the step of adding to a perfume base or a cologne base an aroma augmenting or enhancing quantity of at least one branched chain olefinic chalcogen derivative having the formula:
- ##STR124## wherein Z represents oxygen or sulfur;
- wherein one of the dashed lines represents a carbon-carbon double bond and each of the other of the dashed lines represent carbon-carbon single bonds;
- wherein R.sub.1 represents C.sub.1 -C.sub.4 alkyl;
- R.sub.2 represents C.sub.1 -C.sub.4 alkyl;
- R.sub.3 represents hydrogen, C.sub.1 -C.sub.3 lower alkyl or C.sub.1 -C.sub.3 lower acyl.