In search of nascent musks ... or not

Abstract

1 ABSTRACT The musk aroma has been valued by perfumers for what seems an eternity. Its characteristic odor is one of the few that can stand alone, unadorned by supportive scents that are required to round out the wide variety of other odor types. In addition, the substantivity and stability of most musks have made them a sought after material for performance based products. In the past one hundred years, a veritable army of researchers from all of the major fragrance houses have attempted to identify the structural sub-units required to provide the ultimate musk aroma chemical. These studies have encompassed everything from the strictly empirical to the QSAR approach and everything in between. The on-going requirement for even higher level performance based aroma chemicals has made the family of musks the most studied of all aroma chemicals, as customers continue to push for better cost performance in finished fragrances. Early and serendipitous empirical studies provided the nitro musks, a cost effective and powerful group of musks. The discovery of these materials fuelled research in the 1960's and 1970's which led to a new class of synthetic musks, the polycyclics. As nitro musks fell into disfavor, polycyclics became the cost effective workhorse in performance based products, and made inroads into the fine fragrance market as well. While an extensive effort was carried out in macrocyclic musks, their high cost of manufacture predicated their only significant use within fine fragrances. With the advent of molecular modeling software and more powerful computers, structure activity and conformational analysis were blended with empirical methods to identify the latest round of super musks. This presentation will focus on the tradition of musk manufacture at BBA and its commitment to be a premier musk aroma chemical manufacturer. After a long history in the manufacture of musk xylene, BBA turned its process chemists and engineers loose in the field of polycyclics and first identified patented technology for the manufacture of Abbalide® and then Tetralide®. Based on the accumulated understanding from these successfil projects, they began a search for a polycyclic ‘supermusk’. Combining empirical and computer based methodologies, they discovered a novel potent musk aroma chemical. Its improved odor performance compared to existing polycyclics sparked process research related to the formylation of aromatic ring systems, a key structural sub unit. From this investigation arose a number of novel and commercially applicable technologies to carry out this transformation.