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IUPAC nomenclature 2013 changed a couple of rules very commonly used in naming simple acyclic compounds. As a result, depending on which nomencalture we choose, the answer to this question varies greatly, as demonstrated in the comments. Educational textbooks, hence, would propose an outdated name that is not PIN (Preferred IUPAC Name) according to the newest standards.

This change has been illustrated in the draft, page 442 (page 58 of P-4, section P-44.3), which reads:

##P-44.3 The principal chain In an acyclic compound, or in a compound composed of chains and rings, the chain on which the nomenclature and numbering is based is called the ‘principal chain’. When there is a choice for the principal chain, the following criteria are applied, in the order listed, until a decision is reached.

$$\mbox{A change to the traditional order of seniority criteria is recommended;}\\ \mbox{the length of the chain is senior to unsaturation.}$$

What was the reason for this change?

Normally, there doesn't need to be a reason for changes. However, a change as drastic and influential as this must have had a reason behind it. I'm thinking a group of [newly discovered] compounds needed a new nomenclature, and I remember I read some news that said vaguely the same thing. Was there a need for revision of the criteria? Why would a nomenclature in which unsaturation is senior be inferior to the new system of IUPAC nomenclature?

IUPAC nomenclature 2013 changed a couple of rules very commonly used in naming simple acyclic compounds. As a result, depending on which nomencalture we choose, the answer to this question varies greatly, as demonstrated in the comments. Educational textbooks, hence, would propose an outdated name that is not PIN (Preferred IUPAC Name) according to the newest standards.

This change has been illustrated in the draft, page 442 (page 58 of P-4, section P-44.3), which reads:

##P-44.3 The principal chain In an acyclic compound, or in a compound composed of chains and rings, the chain on which the nomenclature and numbering is based is called the ‘principal chain’. When there is a choice for the principal chain, the following criteria are applied, in the order listed, until a decision is reached.

$$\mbox{A change to the traditional order of seniority criteria is recommended;}\\ \mbox{the length of the chain is senior to unsaturation.}$$

What was the reason for this change?

Normally, there doesn't need to be a reason for changes. However, a change as drastic and influential as this must have had a reason behind it. I'm thinking a group of [newly discovered] compounds needed a new nomenclature, and I remember I read some news that said vaguely the same thing. Was there a need for revision of the criteria? Why would a nomenclature in which unsaturation is senior be inferior to the new system of IUPAC nomenclature?

IUPAC nomenclature 2013 changed a couple of rules very commonly used in naming simple acyclic compounds. As a result, depending on which nomencalture we choose, the answer to this question varies greatly, as demonstrated in the comments. Educational textbooks, hence, would propose an outdated name that is not PIN (Preferred IUPAC Name) according to the newest standards.

This change has been illustrated in the draft, page 442 (page 58 of P-4, section P-44.3), which reads:

##P-44.3 The principal chain In an acyclic compound, or in a compound composed of chains and rings, the chain on which the nomenclature and numbering is based is called the ‘principal chain’. When there is a choice for the principal chain, the following criteria are applied, in the order listed, until a decision is reached.

$$\mbox{A change to the traditional order of seniority criteria is recommended;}\\ \mbox{the length of the chain is senior to unsaturation.}$$

What was the reason for this change?

Normally, there doesn't need to be a reason for changes. However, a change as drastic and influential as this must have had a reason behind it. I'm thinking a group of [newly discovered] compounds needed a new nomenclature, and I remember I read some news that said vaguely the same thing. Was there a need for revision of the criteria? Why would a nomenclature in which unsaturation is senior, inferior to the new system of IUPAC nomenclature?

IUPAC nomenclature 2013 changed a couple of rules very commonly used in naming simple acyclic compounds. As a result, depending on which nomencalture we choose, the answer to this question varies greatly, as demonstrated in the comments. Educational textbooks, hence, would propose an outdated name that is not PIN (Preferred IUPAC Name) according to the newest standards.

This change has been illustrated in the draft, page 442 (page 58 of P-4, section P-44.3), which reads:

##P-44.3 The principal chain In an acyclic compound, or in a compound composed of chains and rings, the chain on which the nomenclature and numbering is based is called the ‘principal chain’. When there is a choice for the principal chain, the following criteria are applied, in the order listed, until a decision is reached.

$$\mbox{A change to the traditional order of seniority criteria is recommended;}\\ \mbox{the length of the chain is senior to unsaturation.}$$

What was the reason for this change?

Normally, there doesn't need to be a reason for changes. However, a change as drastic and influential as this must have had a reason behind it. I'm thinking a group of [newly discovered] compounds needed a new nomenclature, and I remember I read some news that said vaguely the same thing. Was there a need for revision of the criteria? Why would a nomenclature in which unsaturation is senior be inferior to the new system of IUPAC nomenclature?