New \(ilaliins for Organic Chemistry Proposed B.0.4,lON4[K.3CEQ[N.B]].3,9QCisthe notation for 3,3'-dinieth.oxy-4,4'-bis(3"naphthaleneearbox3ranilide-l/r - azo)diphenyl, commonly called dianisidine blue, in a n e w system of notation for organic compounds worked out b y G. Malcolm Dyson of Genatosan, Ltd., Loughborough, England. Since its a n n o u n c e m e n t a few m o n t h s ago, interest in t h e system has grown steadily, principally because it introduces a unique concept t o organic nomenclature. To t e s t t h e validity of t h e system 3,970 compounds t a k e n from the Ring I n d e x were considered and over 9 0 % could be coded in less t h a n 20 symbols, while o n an average the corresponding names used 45 terms. N o compound has yet b e e n encountered which cannot be reduced t o a linear expression of the t y p e shown above. D r . Dyson cites several reasons w h y need for an orderly system of notation for organic compounds exists. First, the Geneva system has been u n a b l e t o supply satisfactory a n d logical n o m e n c l a t u r e to the increasingly complex fused a n d hetero cyclic r i n g systems being p r o d u c e d . F u r ther, t h e use of c o m m o n or " t r i v i a l " names where t h e Geneva s y s t e m h a s failed to furnish a n acceptable label and the failure o n the part of m a n y organic chem ists to a d o p t fully the G e n e v a system have a d d e d t o the confusion of indexers and researchers. T h i s confusion has been compounded b y the failure of the dif ferent countries to adopt a uniform sys tem of enumeration. W i t h t h e hope of remedying t h e situa tion D r . Dyson has proposed a new sys tem of notation, the purpose of which he summarized as follows: 1. T o provide a unique linear expres sion delineating the full s t r u c t u r e of an organic compound irrespective of its com plexity. 2. T o provide t h e linear equivalent in a form t h a t is convenient for indexing a n d has a unique and unequivocal e n u m e r a tion. 3. T o maintain certain mathematical implications in the cipher, so t h a t t h e mechanical manipulation, sorting, select ing, a n d the enumeration of empirical formulae can be effected b y suitable m a chines. T h e symbols and notation used are a r b i t r a r y b u t simple, consisting of the letters of the alphabet (using θ instead of capital Ο to avoid confusion with zero), arabic numbers, parentheses, brack ets, diagonals, periods, c o m m a s , semi colons, h y p h e n s , and the sign of a series (. . . ) . T h e code is divided i n t o sections m a r k e d off b y periods, e a c h section being an operation. A number following a sym bol w i t h o u t t h e interposition of a comma or p e r i o d is termed a modulant. A number immediately preceding a symbol is re ferred t o as a iocant V O L U M E
2 5,
NO.
12
»
»
T h e m a n n e r in which the s y s t e m func tions can b e s t be illustrated b y examples of various classes of organic compounds. T h u s , s a t u r a t e d straight-chain hydrocar bons are indicated b y t h e letter C followed by a n u m b e r (modulant). E t h a n e be comes C2, p r o p a n e C 3 , and octane C8. Branched chains are coded i n t e r m s of t h e longest chain, with branches being a d d e d in order of decreasing size. Two or more like groups are added in a single operation, t h e locants of their position being separated by commas. T h u s , 2,2,4C indicates t h r e e m e t h y l groups in t h e positions n u m b e r e d . I t will be noted in t h e following example t h a t every carbon a t o m is n u m b e r e d in order as it appears in the code, "providing an unalterable e n u m e r a t i o n p a t t e r n based on t h e sim plest of r u l e s " . CH3
T h e complete handling of t h e aromatic compounds is m u c h t o o long a n d detailed to b e presented here, b u t a brief considera tion of a few major points will give some concept of t h e procedure followed. All aromatic rings are related t o t h e six con ventional rings which carry symbols as follows:
I
CH8—C—CHS
I
CH 3 C3.2,2C OH :i CH0CII3 CHoCH-CH.·, 1 ! " I C H r - C—CHoCHoCiT—CHoCIi ! " "I CII3 CHoCH-CHa C10.4C3.6C2.9,9C U n s a t u r a t i o n is indicated b y the letter Ε with m o d u l a n t s as follows: Ε O r d i n a r y double b o n d E l Double bond with cts-arrangement of groups E 2 Double bond with ircms-a rrangement of g r o u p s E 3 Triple b o n d I n the proposed system ethylene is represented a s C2.E, b u t a d i e n e is C4.1,3E, a n d C4.2E1 and C4.2E2 a r e cis- and frans-butene-2, respectively. Unsatura t i o n is cited after the skeleton h a s been delineated a n d Ε operations a r e coded in o r d e r of t h e i r m o d u l a n t s as illustrated below: CH3 CH3
'
W h e r e several rings arc present in the s a m e s t r u c t u r e they are cited in order of seniority T, J, K , W, B , V, A C . Common variations of a r o m a t i c rings are designated by a d d i n g a m o d u l a n t to t h e symbol for the basic ring, and less commonly used ring structures or new c o m p o u n d s are n o t e d b y adding the necessary symbols to the basic code i n a m a n n e r similar to t h a t used for noncyclic hydrocarbons. A simple example of a n aromatic compound would be as follows: CH3
I S\— CHoCi I
!
CH3
CrIo=CHCCII2CHoCH,CCH.
!
I
C=CCH3 CH3 C9.4C2.4,8,8C.10E.2E3 Cyclic h y d r o c a r b o n s are noted b y u s i n g the letter A to signify t h a t a ring h a s been formed. A C 3 represents cyclo p r o p a n e a n d A C 6 cyclohexane. Rings a r e always cited prior t o linear appendages as shown i n the example t h a t follows: CH, Cria
!!
CH
v
X
CH3 AC6.C3.3,3,8C.5,7E M A R C H
2 4,
1947
B.1,2,4C.8CL H e r e the L indicates t h e chlorine a t o m . F u n c t i o n a l groups have t h e i r own s y m bols, as, for example, Q for hydroxyl, E Q for carbonyl, a n d X for carboxyl. S o m e common organic compounds would be designated as shown. CH3COOH C2.X
CH3COCH3 C3.2EQ
Special rules for t h e nitrogenous groups are Ν for amino, N 2 for n i t r o , a n d N 4 for azo. Examples of this notation are B.C.2,4,6N2 for trinitrotoluene and B.0N4 for azobenzene. T h e θ is used t o indicate the joining of two identical rings directly or t h r o u g h a single carbon a t o m . (Continued on page 891) 847
(ÎVIisceîlaneous C o n t i n u e d ) T R A N S A C T I O N S AND A B S T R A C T I N G of technical and scientific articles from F r e n c h , German, Russian, and Polish, by graduate chemical engineer. J o u r n a l references t o publications available in N e w York libraries acceptable. Box 911-L-3, Chem. & Eng:. News, Easton, Pa._ W A N T E D : Silica dishes 7" to 10" deep a n d 16" to 2 0 " diameter. Porcelain dishes I S " to I T " diameter. Box 903-I/-3, Chem. & Eng. News, E a s t o n , P a . W E O F F E R S P E C I A L P R O D U C T S : Silicon 99.87 fine p o w d e r — C a l c i u m Hydride in quant i t y — Aluminum Bromide, Carbide, Sulfide — Fused T i t a n i u m — All Azides — Borides — Carbides — Fluorides — Hydrides — Nitrides — Vanadates—Vermiculite— Choice"African Malac h i t e — Black J a d e — Select Turquoise. Box 9 0 4 - L - 3 , Chem.
