R-0.1.8.1 Nondetachable prefixes that modify the skeletal structure of a parent hydride are cited in alphabetical order immediately preceding the name of the parent hydride. This type of prefix is found commonly in names of natural products (stereoparents) and is discussed more fully in Section F of the IUPAC Nomenclature of Organic Chemistry; however, they are occasionally encountered in trivial and semisystematic names, for example, homocubane.
R-0.1.8.2 Nondetachable prefixes ("a" replacement terms commonly known as "a" prefixes) that indicate replacement of skeletal atoms of a parent hydride are cited in the order of appearance in R-9.3, immediately preceding nondetachable skeleton-modifying prefixes (see R-0.1.8.1), if any, for example, .
R-0.1.8.3 Detachable prefixes describing substituents are cited preceding nondetachable prefixes (see R-0.1.8.1 and R-0.1.8.2), if any, and are alphabetized as follows:
(a) Simple prefixes (i.e., those describing atoms and unsubstituted substituents) are arranged alphabetically; multiplying affixes, if necessary, are then inserted and do not alter the alphabetical order already established.
(b) The name of a prefix for a substituted substituent is considered to begin with the first letters of its complete name.
Examples to R-0.1.8.3(a)
(c) When two or more prefixes consist of identical roman letters, priority for citation is given to that group which contains the lowest locant at the first point of difference.
Example to R-0.1.8.3(b)
(Difluorobutyl as a complete substituent is alphabetized under "d".)
(d) o- (ortho), m- (meta), and p- (para) substituents, if otherwise identical, are arranged in that order (the same as their numerical equivalents, 2-, 3-, and 4-, respectively).
Example to R-0.1.8.3(c)
R-0.1.8.4 Subtractive prefixes (such as anhydro-, dehydro-, demethyl-) have been used as "detachable" or "nondetachable" in previous editions of the IUPAC Nomenclature of Organic Chemistry, but in these recommendations, they are presented as nondetachable.
Example to R-0.1.8.3(d)
R-0.1.8.5 Additive prefixes. According to the previous edition of the IUPAC Nomenclature of Organic Chemistry (C-16.11), the additive prefixes "-dihydro-", "tetrahydro-", etc., could be either detachable and alphabetized among the set of substitutive prefixes, or nondetachable and cites after the substitutive prefixes. In this guide these prefixes are presented as nondetachable.
Example to R-0.1.8.4
Example to R-0.1.8.5
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