FRENCH ORGANIC NOMENCLATURE BY NOEL L o u c n 1 Faculte des Sciences de Caen, France
F r e n c h Organic C h e m i s t s as a whole have always been convinced of the u s e f u l n e s s of s y s t e m a t i c nomenclature. The r a p i d growth of o r g a n i c c h e m i s t r y a f t e r 1860 r e n d e r e d n e c e s s a r y s o m e i n t e r n a t i o n a l a g r e e m e n t in t h i s field. At the occasicin of the 1889 exhibition in Paris, a c o m m i t t e e w a s c r e a t e d , and a f t e r forty-five p r e l i m i n a r y m e e t i n g s held i n Paris, the Geneva C o n g r e s s proposed i n t e r n a t i o n a l r u l e s i n 1892. G e r m a n and F r e n c h C h e m i s t s have had a leading influence i n the e l a b o r a t i o n of Geneva n o m e n c l a t u r e , which, a s a consequence, r e ceived r a t h e r good acceptance in F r a n c e , in G e r m a n y , and in the surrounding c o u n t r i e s , e x cept f o r the I'oic acid" n o m e n c l a t k e , f o r linguistic r e a s o n s p e c u l i a r t o G e r m a n languages. A v e r y innportant c h a r a c t e r of Geneva Rules was that they intended t o give one official n a m e f o r any o r g a n i c compound. Unfortunately Geneva Rules w e r e far f r o m finished and t h e i r c o v e r a g e of o r g a n i c c h e m i s t r y was u t t e r l y insufficient. On the o t h e r hand, t h e first World W a r d i minished the G e r m a n o - F r e n c h influence in C h e m i s t r y t o the benefit of English-speaking C o u n t r i e s . Chemical A b s t r a c t s w a s gaining i n i m p o r t a n c e , and had t o c r e a t e , f o r i t s own p u r p o s e , a n o m e n c l a t u r e which would c o v e r the e v e r i n c r e a s i n g field of C h e m i s t r y . However, the B e i l s t e i n Handbook obviously was obliged t o maintain its e d i t o r i a l policy giving. whenever p o s s i b l e , p r e f e r e n c e t o Geneva n a m e s . It w a s in t h e s e c i r c u m s t a n c e s that Lidge Rules w e r e p r e p a r e d . They w e r e not intended t o give official n a m e s as Geneva Rules did. They only t r i e d t o give a p r a c t i c a l n o m e n c l a t u r e without i n t e r f e r i n g with the editorial policies of B e i l s t e i n and of Chemical A b s t r a c t s . In s o m e way, the L i e g e Rules r e c o g n i z e the f a c t that a l o t of Geneva n a m e s had failed t o gain g e n e r a l a c c e p t a n c e , e i t h e r b e c a u s e they s e e m e d too complicated o r b e c a u s e c h e m i s t s w e r e not sufficiently conscious of the fact that a good fiomenclature is w o r t h s o m e r e a l efforts. As a consequence, Liege Rules gave up what was the e s s e n t i a l p u r p o s e of Geneva Nomenclat u r e : the c r e a t i o n of a unique and unequivocal official name f o r e v e r y o r g a n i c compound. Some of the m o t i v e s of this renunciation c a n be understood. The m a i n r e a s o n w a s p r o b ably the i d e a that c h e m i c a l n a m e s ought t o be s i m p l e . Unfortunately s i m p l e n a m e s a r e t h e apanage of s i m p l e compounds, and with the
d i s c o v e r y of complicated compounds, we have t o a c c e p t complicated n a m e s . Very good f e a t u r e s of Geneva nomenclature have been s a c r i f i c e d t o the d e s i r e of simplifying the n a m e s at any cost. One of t h e s e f e a t u r e s was the maintenance of the s a m e p a r e n t name f o r all the functional d e r i v a t i v e s p o s s e s s i n g the s a m e c a r b o n skeleton. The r e l e n t l e s s n e s s with which this fundamental p r i n c i p l e h a s been fought by people who had nothing t o give in exchange is t r u l y beyond belief. As a m a t t e r of c o n s e quence, m o s t "nomenclature conscious" people i n F r a n c e c o n s i d e r e d Liege Rules with mixed feelings. They welcomed this effort toward a m o r e extensive t r e a t m e n t of n o m e n c l a t u r e p r o b l e m s , but felt quite uneasy when confronted with the p r i c e paid: the m o r e o r l e s s t a c i t renunciation of i m p o r t a n t p r i n c i p l e s included into Geneva nomenclature. They thought it n e c e s s a r y t o complement and s o m e t i m e s t o amend Liege Rules, as w a s done i n t h e " T r a i t e d e Chimie Organique," published u n d e r the e d i t o r s h i p of V. G r i g n a r d i n 1935 and after. After t h e second World War, the Englishw r i t t e n chemical l i t e r a t u r e gained still m o r e i m p o r t a n c e , with the r e s u l t that the Chemical A b s t r a c t s a p p r o a c h i n n o m e n c l a t u r e gained a l a r g e r acceptance in F r a n c e , where s e v e r a l l a b o r a t o r i e s switched f r o m Z e n t r a l b l a t t to Chemical A b s t r a c t s f o r t h e i r g e n e r a l documentation. At the t i m e of the Z u r i c h C o n g r e s s (1955), r u l e s w e r e a g r e e d upon which provide a good c o v e r a g e of h y d r o c a r b o n s and h e t e r o c y c l e s , but the r e v i s i o n of the n o m e n c l a t u r e of functions was still t o come. The "Comitk National de la Chimie" cons i d e r e d that this situation could not continue without r e a l damage f o r the F r e n c h Chemical nomenclature. A comprehensive text was needed a s a guide f o r A u t h o r s , and m o r e s p e cially f o r b e g i n n e r s whose nomenclature had a tendency t o become a hodge-podge of Geneva, Chemical A b s t r a c t s , a n d v e r y p e r s o n a l p r o c e d u r e s . Accordingly, the Bulletin de la Sociktb Chimiaue d e F r a n c e of J a n u a r v 1957 Published a s e t of r u l e s intended t o give p r o p e r guidance t o F r e n c h Authors.
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T h e s e r u l e s r e c e i v e d good acceptance in F r a n c e , and the unavoidable c r i t i c i s m was l i m i t e d t o s p e c i a l points of m i n o r i m p o r t a n c e . The m o s t c o n t r o v e r s i a l question s e e m e d t o b e
'Presented before joint meeting of the Division of Chemical Litancure m d Division of Organic Chemistry, American Chemical Society Meeting, Chicago, Illinois, Yieptemba 8, 1958.
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Noel Lozac'h
whether one should s a y "ethanoique" only o r "acide ethanoique" for a c e t i c acid. The b a s i s of the w o r k was the r u l e s adopted in Liege and a f t e r w a r d s by the International Union of C h e m i s t r y . Some of the initial Geneva r u l e s , left unchanged in L i e g e , a l s o found t h e i r p l a c e . However, the International r u l e s a r e , on s o m e i m p o r t a n t points, v e r y unsufficient. Considering that Chemical A b s t r a c t s i s t h e a b s t r a c t i n g periodical m o s t widely used by F r e n c h C h e m i s t s , the F r e n c h Nomenclature Committee thought i t reasonable t o follow t h e i r p r a c t i c e w h e r e International Rules a r e not sufficient and when t h e r e i s no s t r o n g i n t e r f e r e n c e with e s t a b lished F r e n c h habits. F o r i n s t a n c e , until a n International r u l e i s m a d e , i t h a s been decided t o follow m o s t of the Chemical A b s t r a c t s p r a c t i c e s concerning the placing of p r e f i x e s and suffixes, As they s t a n d , the r u l e s which have been published in the Bulletin d e l a Societe Chimique a r e not stringent and l e a v e the possibility of too many n a m e s . This w a s unavoidable. O t h e r w i s e t h e r e would have been a g r e a t r i s k of having t h e s e r u l e s conflict with International r u l e s now under consideration.
This can be accompiished e a s i l y by denoting supplementary spirounions j u s t a s supplement a r y bridges in polycycloalkanes. It i s quite simple t o consider a s p i r o - a t o m a s a special type of bridge-head w h e r e both ends of one bridge a r e fixed. This is shown in F i g u r e 1. 12
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Fig. 1.1--C.A. numbering: Dispiro r4.2.5.2.1 pentadecane 10
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F i g . 1.2--Extension of v . Baeyer s y s t e m : Dispiro [5.5.431 pentadecane
NOMENCLATURE O F HYDROCARBONS AND HETEROCYCLES L e t u s now t u r n t o s o m e specific p r o b l e m s which need consideration. The Paris Rules (1957) a r e the b a s i s of F r e n c h nomenclature f o r hydrocarbons and h e t e r o c y c l e s . T h e s e r u l e s reflect a g r e a t effort toward codification of e x isting p r a c t i c e . They have a l r e a d y r e c e i v e d long d i s c u s s i o n s in o r d e r t o find s a t i s f a c t o r y c o m p r o m i s e s . However, g e n e r a l acceptance was not p o s s i b l e f o r e v e r y r u l e , and this s i t u a tion has led i n s o m e c a s e s t o the existence of "alternate" r u l e s . F r e n c h A u t h o r s , being a c customed t o the n a m e s u s e d in Chemical Abs t r a c t s probably will choose the r u l e s c o r r e sponding t o Chemical A b s t r a c t s p r a c t i c e . However, t h i s p r a c t i c e does not s e e m e n t i r e l y s a t i s f a c t o r y in s o m e i n s t a n c e s and f u r t h e r a m e n d m e n t s would be appreciated. (a) P o l y s p i r o alkanes The C h e m i c a l A b s t r a c t s n a m e s apply only t o l i n e a r polyspiro a r r a y s . The existing s y s t e m cannot be u s e d with branched a r r a y s . Only the lengths of the connecting chains a r e given i n Chemical A b s t r a c t s n a m e s . T h e s e n u m b e r s can be c o r r e l a t e d t o d s t r u c t u r a l f o r m u l a only if a supplementary assumption i s m a d e . H e r e i t i s admitted implicitly that any ring cannot contain m o r e than two s p i r o - a t o m s . It would be useful t o r e c o n s i d e r "polyspiroalkanes" r u l e s in o r d e r t o b r i n g t h e m in b e t t e r alignment with the "polycyclo alkanes ' I r u l e s .
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F i g . 1.3--C.A. numbering: T r i s p i r o k.2.2.2.2 ,a pentadecane 15
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Fig. 1.4--Extension of v . B a e y e r s y s t e m : T r i s p i r o [5.5.Z3291 1 2
14 13 Fig. 1,5--Extension of v. B a e y e r s y s t e m : T r i s p i r o [2.8.26.291 pentadecane
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FRENCH ORGANIC NOMENCLATURE 8
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F i g . 3.1--Oxa-aza name: 2 g - 1,4a - Di a z anaphthal ene F i g u r e 3.1 gives the Chemical A b s t r a c t s n a m e , and F i g u r e 3.2 gives t h e oxa-aza name f o r the s a m e compound. ( c ) Multiple fusion n a m e s
I refer to names such a s : 10
'0.;2 i
r
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P y r i d o [ l ' , 2 ' : l,21 imidazo [4.5-blquinoxaiine
113 T h i s compound, with the oxa-aza convention, would be named: 8
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:o
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4 a , 5 , 1 0 , 1 l - T e t r a z a b e n z o [h1fluorene
F i g . 2--Bicycles i r o b i c y c l o d i s p i r o 2.2.1.5 2 .1 8,1? .5 6 .4 5 l d o c o s a n e (b)
Numbering of f u s e d h e t e r o c y c l e s
Most F r e n c h c h e m i s t s c o n s i d e r t h a t it is u n d e s i r a b l e t o give a different numbering t o t h e s k e l e t o n when an. h e t e r o a t o m o c c u r s i n a fusion position. T h e r e i s a tendency t o maintain t h e nuinbering of the homocyclic analog. As t h e s p e c i a l numbering of fusion h e t e r o a t o m s i s u s e d by Chemical A b s t r a c t s only in fusion n a m e s , t h e b e s t solution is t o u s e "a" n a m e s i f it is d e s i r e d t o maintain t h e numbering of t h e homocyclic fused system. The d i f f e r e n c e between t h e two methods is shown i n F i g u r e 3 . n
1 expect that m o s t F r e n c h c h e m i s t s will e n counter g r e a t difficulties i n coining multiple fusion n a m e s p r o p e r l y , that i s t o s a y , according t o e x i s t ing International r u l e s . The o x a - a z a method s e e m s r e a l l y sin-.pler. Multiple fusion n a m e s do not have the evocative power of s i m p l e fusion n a m e s , which give d i r e c t l y a g e n e r a l i d e a of the s t r u c t u r e . It s e e m s hopeless fusions. t o u s e n a m e s implying t h r e e , f o u r ,
e.,
A good solution would be a s y s t e m s u c h a s that of Dyson- T a y l o r P a t t e r son.
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(d) P o l y - s p i r o -onium compounds T h e s e compounds s e e m b e s t named with "polyazonia" p r e f i x e s . F o r example:
1 1 12 13 14 1
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5 , 8 - D i a z o n i a d i s p i r o r4.2.4.21 t e t r a d e c a n e F i g . 3 . 1 - - C . A. fusion n a m e : 2H-Pyrido [ 1 , 2 - ~pyrimidine ]
H e r e a l s o , the r e m a r k s p r e v i o u s l y m a d e concerning t h e nomenclature of polyspiroalkanes should b e taken into account.
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Noel L o z a c ' h
NOMENCLATURE O F FUNCTIONS Chemical A b s t r a c t s has developed a method which i s based mainly upon codification of c u r r e n t p r a c t i c e . The complexity of nomenclature i s i n c r e a s i n g e a c h y e a r , s o a g r e a t e r effort toward systematization i s now n e c e s s a r y . One can r e a d in t h e Introduction t o Liege Rules that official n a m e s a r e no longer n e c e s s a r y owing to the e x i s t e n c e of f o r m u l a indexes. N e v e r t h e l e s s , the number of e n t r i e s under the s a m e molecular f o r m u l a can be s o l a r g e that the usefulness of good official n a m e s i s now evident. At l e a s t , a s e r i o u s effort is needed i n o r d e r t o avoid an e x c e s s i v e p r o l i f e r a t i o n of possible n a m e s for the s a m e compound. Existing p r a c t i c e evidently should r e c e i v e p r o p e r consideration but, f o r f u r t h e r developm e n t s of n o m e n c l a t u r e , i t i s e x t r e m e l y i m p o r tant to d e r i v e the r u l e s f r o m a l i m i t e d number of c l e a r l y established p r i n c i p l e s . I shall now consider how t h i s rationalization of existing p r a c t i c e c a n be attained in s o m e p a r ticular cases.
of hydrogenation, should be applied t o the "main name" considered as a unit. In f a c t , when t h i s question was r a i s e d s o m e y e a r s ago before the F r e n c h Nomenclature Committee, we r e a c h e d the conclusion that i t was n e i t h e r s i m p l e nor logic a1 t o t r e a t indicated hydrogen in two diff e r e n t ways. This point of view l e a d s t o n a m e s such a s those given in F i g u r e s 4.1 and 4.2. H e r e , the keto group o r groups a r e considered a s p a r t of the skeleton and indicated hydrogen i s considered a f t e r w a r d s , only if n e c e s s a r y .
F i g . 4.1
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Benz [ G l a n t h r a c e n - 7 - o n e
( a ) Skeletal nomenclature According t o t h i s s y s t e m , the skeleton of molecules i s c o n s i d e r e d f i r s t . A p a r e n t c o m pound i s the one which contains the m a x i m u m number of noncumulative double bonds p e r mitted by the skeleton. It happens that the name applies equally t o i s o m e r s differing by the p o s i tion of one o r m o r e hydrogen a t o m s i n t h e s t r u c t u r e . Then, the n a m e can be m a d e specific by indicating the position of such hydrogen a t o m s . F o r this p u r p o s e the n a m e i s p r e c e d e d by the locant( s ) of the hydrogen a t o m ( s ) , followed by italic capital g f o r e a c h a t o m . In International r u l e s , s k e l e t a l nomenclature i s a l r e a d y d e s c r i b e d f o r hydrocarbons and fundamental h e t e r o c y c l e s . The s a m e method i s a l s o u s e d by Chemical A b s t r a c t s f o r s o m e functional d e r i v a t i v e s , but with a s p e c i a l convention f o r indicated hydrogens, which a p p e a r between parentheses. The trouble i s that s k e l e t a l nomenclature has the s a m e terminology a s c l a s s i c a l s u b s t i tutive nomenclature. E x a m p l e s : Oxa-, Aza- p r e f i x e s , -one, -thione suffixes Thus, i t i s i m p o r t a n t t o m a k e a c l e a r cut distinction between the t e r m s which a r e u s e d with a skeletal meaning and t h o s e which a r e only used with a substitutive meaning. The u s e fulness of the idea of "main name" is t h a t it s e t s a c l e a r distinction between different p a r t s of a complex name f o r which different logical methods a r e u s e d . It would be t h e subject of a c l e a r rule t o s a y that the s k e l e t a l p r i n c i p l e , with a l l i t s consequences concerning t h e s t a t e
F i g . 4.2
- lH-Benz[d.e]anthracene-6, 1 I-dione -
This point of view l e a d s t o a r e a p p r a i s a l of t h e s t a t u s of hydro p r e f i x e s which i s considered next. (b) P l a c e of the "Hydro" p r e f i x e s These p r e f i x e s a r e now mixed with t h e o t h e r p r e f i x e s denoting substitution. This i s quite illogical and l e a d s t o trouble. It would be far b e t t e r t o admit that substitution p r e f i x e s apply to the " m a i n name" c o n s i d e r e d as a whole. The m a i n n a m e should contain the hydro p r e f i x e s , because hydrogenation of the s t r u c t u r e often needs t o be m a d e before substitution is possible. The c a s e f o r hydro p r e f i x e s is the s a m e a s f o r "a" p r e f i x e s . Both types of p r e f i x e s m a y p r e s u m e of substitution and should be included within t h e m a i n name. The logical place f o r hydro p r e f i x e s is immediately b e f o r e indicated hydrogen, b e c a u s e the chemical meaning of t h e hydro l o c a n t s i s s t r i c t l y identical with the meaning of the indicated hydrogen locant. F o r i n s t a n c e , t h e 1,2-dihydro derivative of 3Hbenz [b.] a n t h r a c e n e i s 2,3-dihydro- 1Hbenz[d.e.] a n t h r a c e n e . This is the r e a s o n why F r e n c h Rule F.4 (Bull. SOC.Chim. 1957, p . 59) proposed t h e following s c h e m e :
FRENCH ORGANIC NOMENCLATURE
Substitution p r e f i x e s
Examples:
/ Hydro p r e f i x e s
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Main n a m e
Indicated hydrogen
I
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"Oxa - a z a - etc , prefixes
P a r e n t n a m e , including fusion prefixes
Unsaturation suffixes
\ F u n c t i o n a l suffixes
F o r i n d e x e s , such a m a i n n a m e would cons t i t u t e a good main e n t r y . F o r i n s t a n c e 1,2,3,4t e t r a hydr onap ht halene de rivative s would oc c u r u n d e r t h e sarne heading, which is m u c h m o r e s a t i s f a c t o r y f r o m the chemical point of view. ( c ) Choice of the p r i n c i p a l function F o r the t i m e being, F r e n c h Authors a r e r e quested to u s e the s e n i o r i t y o r d e r adopted in Likge. When the Likge Rule is not sufficient, the Chemical A b s t r a c t s n a m e s often a r e u s e d a s m o d e l s fo.r the choice of the p r i n c i p a l funct i o n s . The t a s k would be made much e a s i e r i f a g e n e r a l s e n i o r i t y r u l e w e r e available. Such a r u l e should codify existing p r a c t i c e 2nd i n t r o duce a s few changes a s p o s s i b l e . If t h i s s e n i o r i t y o r d e r i s t o be u s e d only f o r the choicie of the "principal function," we do not have t o c o n s i d e r functions which c a n be e x p r e s s e d only by p r e f i x e s , f o r i n s t a n c e :
F , C1, B r , I, NO, NO2, P O , PO2,IO, IOz,ClO3
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Ethyl benzoate Butyl methyl sulfide
Ionic n a m e s a r e r e q u i r e d f o r a c o r r e c t d e s c r i p t i o n of the chemical s t r u c t u r e . TO the c o n t r a r y m o s t radico-functional names may be replaced by substitutive n a m e s . In English n a m e s , the so-called "functional ending" is s o m e t i m e s r e a l l y a suffix, but it a l s o m a y be the end of radico-functional name such a s "pentanoyl chloride , I 1 In F r e n c h "pentanoyl chloride" i s t r a n s l a t e d by " c h l o r u r e de pentanoyle," and in F r e n c h the equivalent of the S O called functional ending ':oyl chloride" does not e x i s t , because "Chlorure" ought to come at the beginriing and not a t the end of the name. This difference should always be borne in mind when comparing F r e n c h and English nomenclature f o r this type of n a m e . It i s not a question of chemical nomenclature but of grammar. As a r u l e , this i n v e r s i o n of the name i s t o be found f o r oxyacids (carboxylic, sulfonic, e t c . ) , t h e i r e s t e r s and t h e i r halides. The choice o f such a function as the principal one means that the n a m e should be of the substitutive -functional (%, acide benzene sulfonique) o r of the r a d i c o functional type (e.g., C h l o r u r e de benzoyle). In F r e n c h , radico-functional names a r e l e s s favored f o r e t h e r s and sulfides, the p r e ''alkylthio," G., being fixes "alkoxy," e&., p r e f e r r e d , even i f t h e r e is no other functional ending. T h e s e habits a r e f i r m l y rooted in the mind of F r e n c h c h e m i s t s and to advocate a d r a s t i c change has s o m e chance of s u c c e s s only if we c a n offer a r e a l l y b e t t e r a l t e r n a t e s y s t e m , with a convenient and c l e a r s e n i o r i t y o r d e r of the functions. If such a s y s t e m i s proposed on an international b a s i s , I a m quite s u r e that F r e n c h c h e m i s t s will m a k e an effort t o get r i d of old habits. On the c o n t r a r y , one cannot hope to enforce a r u l e in F r a n c e concerning principal functions without a good logical b a s i s , which by the way, would be equally useful t o n o n - F r e n c h speaking people. This p r o b l e m h a s s o m a n y implications that we can't d i s c u s s it h e r e in detail. We wish only to s a y that i t s e e m s p o s s i b l e t o g e n e r a l i z e the s e n i o r i t y o r d e r u s e d by Chemical A b s t r a c t s without r e s o r t i n g t o d r a s t i c changes.
(=GoH)
The "acinitro" group should not belong t o t h i s group. It should r e c e i v e the s a m e t r e a t m e n t a s phosphinic a c i d s (>Pa '
'OH''
The choice of the p r i n c i p a l function i s the choice of the ending of a n a m e , and the m a t t e r has been somewhat o b s c u r e d by a long l a s t i n g confusion between ionic n a m e s and r a d i c o functional nairnes . When a n a m e i s given t o an ion, the ionic endings -ium. - a t e , -ide ought t o be u s e d in m o s t c a s e s . A few exceptions seem u s e f u l , s u c h a s the "diazonia-dispiro" n a m e s . F o r a s a l t , the n a m e s of two ions a r e given: Examples : Tetramethylammonium benzoate I -Methylpyridinium 4-hydroxybenzothiazolyl-2- sulfide Radico-functional n a m e s , although d e s i g n a t ing non-ionic compounds, a r e somewhat s i m i l a r t o ionic n a m e s , the cation only being r e p l a c e d by a r a d i c a l .
(3)
Conjunctive and Geneva n a m e s
Chemical A b s t r a c t s does not seem to like Geneva r a d i c a l n a m e s with functional endings such a s in "anthracene dipentyloic acid" o r "anthracene trimethylol." The principal a d vantage of t h e s e n a m e s i s to p r e s e r v e the functional ending. The s a m e r e s u l t has been obtained in Chemical A b s t r a c t s through the u s e of conjunctive n a m e s s u c h a s l'anthracenedipentanoic acid" o r "anthracenetrimethanol."
6
Noel Lozac'h
The u s e of the l a t t e r n a m e s i s steadily i n c r e a s ing, and this shows t h e c o r r e c t n e s s of the Geneva p r o p o s a l s which gave a possible solution s o m e 70 y e a r s ago. Some F r e n c h a u t h o r s s t i l l u s e the alkyloic n a m e s in conformity with Liege Rules, which maintain Geneva Rules f o r a c i d s . T h e r e is a good r e a s o n f o r this: the F r e n c h language is reluctant t o u s e compound words. In English, i t is quite common t o put two sdbstantives side by s i d e . In F r e n c h s o m e idea of subordination of one substantive to the o t h e r is needed. In the chemical field t h i s i d e a of s u b ordination is e x p r e s s e d by the "yl" p a r t i c l e . However, the difference between the two m e t h ods i s not v e r y i m p o r t a n t , provided that the numbering of the s t r u c t u r e is always the s a m e . If the side chains a r e always n u m b e r e d i n the s a m e way, i t does not m a t t e r v e r y m u c h whether "naphthalene butyloic acid" o r "naphthalene butanoic acid" is written.
CONCLUSION Despite s o m e d i f f e r e n c e s , F r e n c h and Engl i s t nomenclatures in o r g a n i c c h e m i s t r y a r e
v e r y similar. The n e c e s s a r y development of s y s t e m a t i c nomenclature should tend t o i n c r e a s e the scope of the r u l e s by building t h e m upon g e n e r a l principles quite independent of the g r a m m a t i c a l c u s t o m s of any national language. This i s why substitutive n a m e s a r e of g r e a t value f o r International u s e . And l a s t , but not l e a s t , i n a field w h e r e the g r a m m a t i c a l habits d o not i n t e r f e r e , special efforts ought t o be e x e r t e d t o achieve a gene r a l l y a g r e e d upon s y s t e m of numbering c o m plex s t r u c t u r e s . A l a r g e quantity of w o r k and money is l o s t e v e r y y e a r through m i s u n d e r standing of numbering. The F r e n c h C o m m i s s i o n f o r Organic Nomenclature thinks that p r o p e r consideration should be given t o a s y s t e m a t i c numbering of o r g a n i c s t r u c t u r e s s u c h as the one s e t f o r t h by the International C o m m i s s i o n f o r Codification and Ciphering. The Dyson-TaylorP a t t e r s o n s y s t e m f o r polycyclic s t r u c t u r e s h a s been published a l r e a d y in the Bulletin d e l a Societe Chimique (1957, p. 45). I t is not e a s y f o r nomenclature t o keep p a c e with the e v e r i n c r e a s i n g r e s u l t s i n chemical r e s e a r c h . G r e a t c a r e should be given t o the g e n e r a l logic of the s y s t e m , b e c a u s e the logic of today is the practicability of t o m o r r o w .
