This webpage allows you to obtain the predicted perceptual similarity, expressed in radians, between any pair of complex odorant formulas. The calculation is based on a study by Ravia et al (2020) published in the journal Nature.
The higher the value in radians, the more perceptually different the odorants. Odorants less than 0.05 radians apart are very similar to each other, and odorants less than 0.0125 radians apart are likely indiscriminable by most people.
How to use OdorSpace Advanced
The main image contains about 4000 mono-molecules depicted in 3-dimensional space, where the X-axis reflects estimated pleasantness (r = ~0.6) based on a model from odorant structure as detailed in Snitz et al (2019), such that larger values imply greater pleasantness. The remaining axes together reflect the pairwise distances between the odorant molecules. You can click on any molecule to get its coordinates, identifiers, and its descriptors if available. When you select an odorant formula, its molecular components will be highlighted in a corresponding color.
In OdorSpace Advanced you can compare between previously created formulas, and you can compare with formulas you virtually build here.
How to build novel odorant formulas:
1. Highlight "Form. 1"
2A. Select a component using either CAS, CID, Name, or Descriptor.
2B. You can alternatively select a component by clicking on it in the graph
3. Select the % of this component in your final formula*
4. Estimate the perceived intensity of this component as added**
5. Click "Add"
6. Repeat steps 1-5 to add as many components as you want to Form. 1
7. You can now click "calculate", and the results window will tell you which is the closest monomolecule in our database, and which is the closest formula in our (very limited) database. You can click on the monomolecule, and get its descriptors. If your novel formula is within 0.05 radians or less of the monomolecule, then that is what it will smell like. Similarly, if it is within 0.05 radians or less of any of our pre-prepared formulas, then they will smell exactly the same.
8. You can also highlight Form. 2, and go through steps 1-6 to build it as well. You can then press "Calculate" to obtain the predicted perceptual distance between Form. 1 and Form. 2. You can also add Form. 3 in the same way. For each formula, you will also receive the information of step #7.
3*: No need for fancy calculations here: If you have a component that is already in a dilution, here you enter the % of the formula made up by this dilution. For example, if you have a solution of 1% Butanal, and you use this as 10% of your formula, then you enter "10" and not "0.01" or "0.001". We do the calculations.
4**: Here you enter the perceived intensity of the dilution you used for this component. The default values we selected for this entry reflect dilutions as suggested by www.thegoodscentscompany.com for recommended smelling dilution. If you prepared your own dilution, please rate it for perceived intensity. This rating does not need to be very accurate, but rather a rough estimation will do. To calibrate your estimation, consider the following "standards":
Methyl isoeugenol (CID: 7128) at 100% = Very Weak
PEA (CID: 6054) at 100% or Beta-ionone (CID: 638014) at 100% = Weak
para-cresyl isobutyrate (CID: 7685) at 100% = Intermediate
Isovaleric acid (CID: 10430) at 1% or Eugenol (CID: 3314) at 10% = Strong
Citral (CID: 638011) at 100% = Very Strong