Table 3.

Type 2 odorants, seeking possible examples. (Type 2's: ‘plus’ denotes a positive response and ‘minus’ denotes a negative response to whether the odorant is flexible.)

section	enantiomer pair	no.	flexible?	planar?	chiral centre?	electron rich?	other?
cyclic terpenoids	(1R,4S)- and (1S,4R)-cis- and trans-p-menthan-8-thiol-3-ones	1	+	—	1,4	3,4	—
	linalool oxides (pyranoids)	2	+	—	1,4	1,4	2,3
	R- and S-carvones	3	+	—	4	2,4	1
	carvone epoxides	4	+	—	1,2,5	1,2, 3,5	—
	carveols	5	+	2	2,4	2,4	1
	trans-dihydrocarvones	6	+	1	1,4	2,4	—
	carvotanacetols	7	+	2	2,4	2	1
	(2S,4R)- and (2R,4S)-2-acetyl-p-menth-6-enes	8	+	4	2,4	2	1
bicyclic terpenoids	4-cyclohexylmethylene-isopinocamphones	9	+	1	1	2, (E–Z)3	5
ionones, irones, damascones and structurally related odorants	methyl-α-cyclogeranates	10	+	—	2	2	1,3
	methyl-γ-cyclogeranates	11	+	—	2	2,3	1
	trimethyl-cyclohexyl-pentan-3-ones	12	+	2	2,3	2	1
	trimethylcyclohexyl-pent-1-en-3-ones	13	+	2	2,3	2	1
	tetrahydroirones	14	+	1,3	1,3	3	2
	trans-γ-irones	15	+	1	1,3	3,4	2
	theaspiranes	16	+	—	2	2	1,3
acyclics (alcohols, esters, acids, aldehydes)	methylhexanols	17	no ring	—	—	—	—
	2-methylbutanoic acids	18	no ring	—	—	—	—
	2-pentanols	19	no ring	—	—	—	—
	3-hydroxyheptanes	20	no ring	—	—	—	—
	1-hexen-3-ols	21	no ring	—	—	—	—
	1-hepten-3-ols	22	no ring	—	—	—	—
	1-octen-3-ols	23	no ring	—	—	—	—
	1-nonen-3-ols	24	no ring	—	—	—	—
	1-decen-3-ols	25	no ring	—	—	—	—
	3-mercaptohexanals	26	no ring	—	—	—	—
	3-acetylthiohexanals	27	no ring	—	—	—	—
miscellaneous	methyl-1,4-dimethylcyclohex-3-ene-1-carboxylates	28	+	—	4	4	1
	2-methylbutyl-2-methylpyrolidines	29	pentane ring	—	—	—	1,2
	2-methyl-N-(3′-methylbutylidene)butan-1-amines	30	no ring	—	—	—	1,2