IDENTIFICATION AND THEIR ANALYSIS B. G. A.
OF
HIGHER
ALIPHATIC
TRIFLUOROACETATES OF
THE
MASS
V. Rozynov, I. I. Spivakovskii, I. Tishchenko,
PRIMARY
ON THE
SPECTROMETRIC A. Bogdanova, I. I. Zaslavskii, a n d N. S. V u l ' f s o n
BASIS
ALCOHOLS OF
AN
DATA UDC 543.51:547.268
The p r i n c i p l e s of the m a s s s p e c t r o m e t r i c b e h a v i o r of definite types of organic compounds can be used for the e s t a b l i s h m e n t of the s t r u c t u r e of p r e v i o u s l y unknown compounds on the b a s i s of an a n a l y s i s of t h e i r m a s s s p e c t r a u s i n g an e l e c t r o n i c c o m p u t e r . In p a r t i c u l a r , e l e c t r o n i c c o m p u t e r s working a c c o r d i n g to .the p r o g r a m s d e s c r i b e d in [1, 2] a r e being s u c c e s s f u l l y used in the e s t a b l i s h m e n t of the s t r u c t u r e of acyclic aliphatic compounds. According to the p r o g r a m s of [2, 4], the s t r u c t u r a l f o r m u l a of the compound c o r r e s p o n d i n g to a given m a s s s p e c t r u m is e s t a b l i s h e d beginning with the h e t e r o a t o m by s u c c e s s i v e a d d i tion of s t r u c t u r a l e l e m e n t s . The s t r u c t u r a l p e c u l i a r i t i e s of the portions of the h y d r o c a r b o n chain distant f r o m the h e t e r o a t o m , m a n i f e s t e d in the m a s s s p e c t r a , a r e p r a c t i c a l l y not c o n s i d e r e d in the indicated p r o g r a m s . F o r compounds with the c o m p o s i t i o n C 8 and above, the s t r u c t u r a l f o r m u l a cannot be e s t a b l i s h e d unambiguously on the b a s i s of m a s s s p e c t r a l data alone; the RMR method m u s t be used in addition [3], the application of which in the c a s e of complex m u l t i c o m p o n e n t m i x t u r e s involves a n u m b e r of e x p e r i m e n t a l difficulties. In this w o r k a n a l g o r i t h m is p r o p o s e d , p e r m i t t i n g a reduction of the n u m b e r of s t r u c t u r e s obtainable by the e l e c t r o n i c c o m p u t e r only on the b a s i s of the m a s s s p e c t r a l data. T h i s modified algorithm h a s been u s e d to e s t a b l i s h the s t r u c t u r e of higher alcohols and their t r i f l u o r o a c e t y l d e r i v a t e s (TFA) on the b a s i s of the m a s s s p e c t r a . The a l g o r i t h m is b a s e d on the fact known in m a s s s p e c t r o m e t r y , of p r e f e r e n t i a l cleavage of C - C bonds at s i t e s of b r a n c h i n g of the h y d r o c a r b o n chain, The e s t a b l i s h m e n t of the s t r u c t u r a l f o r m u l a of the alcohol (or its TFA) on the b a s i s of the m a s s s p e c t r u m is r e d u c e d to the following two o p e r a t i o n s : A andB. A. D e t e r m i n a t i o n of the G r o s s F o r m u l a of All the Alkyl F r a g m e n t s F o r m e d as a Result of Cleavage of C - C Bonds at Sites of B r a n c h i n g of the H y d r o c a r b o n Chain, i.e., the Sets of Alkyl F r a g m e n t s . The h y d r o c a r b o n ions in the m a s s s p e c t r a of alcohols (or TFA) f o r m e d as a r e s u l t of cleavage of C - C bonds at the s i t e s of b r a n c h i n g a r e easily detected in a c o m p a r i s o n of the m a s s s p e c t r u m of the investigated c o m pound with the m a s s s p e c t r u m of a s t a n d a r d n o r m a l alcohol (or its T F A ) , containing the s a m e n u m b e r of C a t o m s . Series of monotypic homologous ions, the intensities of the peaks of which a r e e x p r e s s e d in p e r c e n t of the s u m m a r y ionic c u r r e n t of the given homoIogous s e r i e s of ions, a r e c o m p a r e d with one another. In the c a s e of c l e a v a g e of the C - C bond in the m o l e c u l a r ion of the alcohol (or its TFA), the positive c h a r g e m a y be l o c a l i z e d on either of the two f r a g m e n t s f o r m e d ; t h e r e f o r e , it is n e c e s s a r y to c o m p a r e two homologous s e r i e s of ions: a s e r i e s of h y d r o c a r b o n ions beginning with C2H5+ ( m / e 29) and a s e r i e s of oxygen-containing ions, beginning with CH2OH ( m / e 31) in the c a s e of the f r e e alcohol o r with C+H2-O - C O - C F 3 ( m / e 127) in the c a s e of their TFA. Henceforth, we shall call these s e r i e s of ions a c c o r d i n g to t h e i r f i r s t m e m b e r s : s e r i e s 29, s e r i e s 31, and s e r i e s 127. In an a n a l y s i s of ions of s e r i e s 29, only the ions, the intensity of the p e a k s of which in the m a s s s p e c t r u m of the i n v e s t i g a t e d alcohol (or its TFA) e x c e e d s the intensity of the c o r r e s p o n d i n g ions in the M. M. Shemyakin Institute of the C h e m i s t r y of Natural Compounds, A c a d e m y of Sciences of the USSR, Moscow. Scientific R e s e a r c h Institute of Organic I n t e r m e d i a t e s and D y e s , M i n i s t r y of the Chemical I n d u s t r y of the USSR, Moscow. T r a n s l a t e d f r o m I z v e s t i y a A k a d e m i i Nauk SSSR, Seriya K h i m i c h e s k a y a , No. 7, pp. 1526-1532, J u l y , 1974. Original a r t i c l e s u b m i t t e d N o v e m b e r 11, 1973. 9 1975 Plenum Publishing Corporation, 227 West 17th Street, New York, N. Y. 100ll. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission of the publisher. A copy of this article is available from the publisher for $15.00.
1446
T A B L E 1. P a r t i a l M a s s S p e c t r a of C e r t a i n P r i m a r y A l c o h o l s [8] o r T h e i r T F A D e r i v a t i v e s * [6] I
Relative intensity, %
i
~
~
]
~
r~
29 /
8,9
I t2,8 ]
8,3
120,2 I/ 87
57 7, 85 99
r 7,3 3,0 5,7 ~,:~ o,,~
I 28,7 I / ~0,6 I / 5,8 / / 2,2 t , 0,8 ~ / 0,5 /
[3,5 t,2 t5,1 0,t -
I I / [ ~ /
] / / | tt3 , ~ / ~4~ / ~55 / ~69 / 31 / ~5 |
59 ~ n /
0,0
/
0,5
|
--
!
--
/
0,t OJ --
t / / ~ /
-
/
%0 / -- / 0,5 1 -- / / 58,6 / --
~9,7
t
~ ~3,:~ ~ / ~,8 /
20,9 5,5 0,8 0,5 -
Aliphatic
Relative intensity, %
l
~
0
--
i/ 1t5 -U127 0,75 II t4i 0,00 li 155 0,23 ,~9 o,,9 11~83 o,.~ /I 197 0,00 -- /l m 0,00 -- // 225 0,56 75,4 /I 239 ] 0,00 ~3,5 |1 25~ / 0,~ 2,2 , 2~ ] o,oo ~,o~1
" I I I / /
...c~
I
-0,00 0,00 0,00 0,00 o,oo
I 0,00
p
' ! / I / t /
.
,,5 ~,0 --
-
1
/ ~176 0,0 [ / 0,_6 i
/ / ]
/ 0,00 | / 0,00 / / 0,00 ]
----
/ 1 ]
|
--
/
0,00
/
[ o,oo I
-
[
* The intensities of the peaks of the ions are given in % of the total ~.onic current of each homolos series of ions, with the exception of series 12'/, for which the intensities of the pea~ of the ions are given in % of the intensity of the maximum peak in the series under consideration. m a s s s p e c t r u m o f a s t a n d a r d s a m p l e b y -> 10%, a r e c o n s i d e r e d . T h e s e i o n s a r e i n c l u d e d in t h e s e t of a l k y l f r a g m e n t s . I n the a n a l y s i s o f s e r i e s 31 a n d 127, o x y g e n - c o n t a i n i n g i o n s a r e c o n s i d e r e d . I n t h e f i r s t c a s e , i o n s , t h e i n t e n s i t i e s o f the p e a k s of w h i c h a r e no l e s s t h a n 50% g r e a t e r t h a n the i n t e n s i t i e s e f the p e a k s o f t h e c o r r e s p o n d i n g i o n s in the m a s s s p e c t r u m of a s t a n d a r d s a m p l e , a r e s e l e c t e d , w h i l e in the s e c o n d c a s e a l l the i o n s of t h e s e r i e s a r e c o n s i d e r e d (ions o f the s e r i e s 127 a r e p r a c t i c a l l y a b s e n t in t h e T F A o f l i n e a r a l c o h o l s ) . T h e v a l u e s of the m a s s n u m b e r s ( g r o s s f o r m u l a s ) of the c o r r e s p o n d i n g o x y g e n c o n t a i n i n g i o n s o f a l k y l r a d i c a l s a r e r e a d i l y o b t a i n e d a s a r e s u l t of d e d u c t i o n o f t h e v a l u e s of t h e m a s s n u m b e r s o f t h e o x y g e n - c o n t a i n i n g i o n s f r o m t h e v a l u e s o f m / e of the m o l e c u l a r i o n s of the c o r r e s p o n d i n g a l c o h o l s (or t h e i r T F A ) . T h e a l k y l f r a g m e n t s o b t a i n e d in t h i s w a y a r e a l s o i n c l u d e d in the s e t . I n a c o m p a r i s o n of the s e t of a l k y l f r a g m e n t s , it i s n e c e s s a r y to c o n s i d e r the f o l l o w i n g p e c u l i a r i t i e s of t h e m a s s s p e c t r o m e t r i c b e h a v i o r of t h e c o m p o u n d s s t u d i e d : a) T h e v a l u e s of m / e of h y d r o c a r b o n i o n s in the m a s s s p e c t r a of a l c o h o l s [5] and t h e i r T F A [6] c o i n c i d e w i t h t h e v a l u e s m / e of i o n s of the t y p e of C H ~ C H 2, w h i c h i s e s p e c i a l l y i m p o r t a n t in the c a s e of T F A -
"o +
2 - m e t h y l - s u b s t i t u t e d a l c o h o l s . I n a n i n v e s t i g a t i o n of t h e i r m a s s s p e c t r a , a s u b s t a n t i a l n u m b e r of o x y g e n c o n t a i n i n g i o n s f a l l in t h e s e t of a l k y l f r a g m e n t s , and t h e c o n s t r u c t i o n of the t r u e s t r u c t u r a l f o r m u l a a c c o r d i n g to the a l g o r i t h m d e s c r i b e d b e c o m e s d i f f i c u l t . H o w e v e r , in t h i s c a s e the s t r u c t u r a l f o r m u l a of t h e c o m p o u n d c a n be e s t a b l i s h e d if the p e c u l i a r i t i e s of the m a s s s p e c t r o m e t r i c b e h a v i o r of 2 - m e t h y l - s u b s t i t u t e d a l c o h o l s a r e a d d i t i o n a l l y c o n s i d e r e d [6]. b) F o r the m a s s s p e c t r a of a l c o h o l s in t h e i n t e r v a l s of m a s s n u m b e r s ( M - 1 2 7 ) > m / e > 127, t h e v a l u e s o f m / e of i o n s o f the s e r i e s 127 c o i n c i d e w i t h the v a l u e s of t h e m a s s n u m b e r s o f h y d r o c a r b o n i o n s . A t l o w e r v a l u e s of m / e , i o n s of the s e r i e s 127 do n o t e x i s t , w h i l e a t h i g h e r v a l u e s h y d r o c a r b o n i o n s do n o t e x i s t . If in the s e l e c t i o n of t h e a l k y l f r a g m e n t s the v a l u e s of t h e i r m a s s f a l l into t h e i n d i c a t e d r e g i o n s , i t i s b e l i e v e d t h a t b o t h h y d r o c a r b o n a n d o x y g e n - c o n t a i n i n g i o n s c o r r e s p o n d to the g i v e n v a l u e o f m / e . c) A l k y l f r a g m e n t s m a y a l s o be f o r m e d a s a r e s u l t of c l e a v a g e of s e v e r a l C - C b o n d s w i t h the o c c u r r e n c e of r e a r r a n g e m e n t p r o c e s s e s [7]. T h e p r o p o s e d m e t h o d of s e l e c t i o n d o e s n o t e x c l u d e t h e p o s s i b i l i t y t h a t t h e i o n s n o t e d a b o v e w i l l f a l l into the s e t o f a l k y l f r a g m e n t s . I t is p r a c t i c a l l y i m p o s s i b l e to t a k e into a c c o u n t a l l t h e s e p e c u l i a r i t i e s of the m a s s s p e c t r o m e t r i c b e h a v i o r f o r c e r t a i n c o m p o u n d s in g e n e r a l f o r m , a n d t h i s s u b s t a n t i a l l y h i n d e r s t h e s e l e c t i o n of the t r u e s t r u c t u r a l f o r m u l a of the i n v e s t i g a t e d a l c o h o l ( o r i t s T F A ) . Two e x a m p l e s i l l u s t r a t i n g t h e m e t h o d of s e l e c t i o n of a l k y l f r a g m e n t s in t h e e s t a b l i s h m e n t o f t h e s t r u c t u r a l f o r m u l a o f T F A - 2 , 4 - d i e t h y l o c t a n o l (I) ( m o l . wt. 282) a n d 2 , 2 - d i m e t h y l - l - p e n t a n o l ( I I ) ( m o l . w t .
1447
116) on the b a s i s of t h e i r m a s s s p e c t r a , a r e d i s c u s s e d below. T a b l e 1 p r e s e n t s the p a r t i a l m a s s s p e c t r a of these compounds, as well as the c o m p l e t e m a s s s p e c t r a of standard s a m p l e s - n-heptanol and T F A - n dodecanol. C o n s i d e r i n g the r u l e s noted above on the b a s i s of T a b l e 1, the following ions in the m a s s s p e c t r a of the compounds under c o n s i d e r a t i o n a r e selected: f r o m a c o m p a r a t i v e a n a l y s i s of ions of s e r i e s 29 for compounds (I) h y d r o c a r b o n ions with m / e 57, 99, 113, and 155 a r e s e l e c t e d , and for compound (II) h y d r o c a r b o n ions with m / e 43 and 85. A c o m p a r a t i v e a n a l y s i s of s e r i e s 127 and 31 leads for compound (I) to oxygen-containing ions with 9m / e 1 5 5 , 1 6 9 , 1 8 3 , 2 2 5 , and 253, and for compounds (II) to o x y g e n - c o n t a i n i n g i o n s w i t h m / e 59 and 101. The ion with m / e 155 [for (I)] m a y be both h y d r o c a r b o n and oxygen-containing; the r e m a i n i n g ions can only be oxygen-containing. After the c o r r e s p o n d i n g deductions, the values of the m a s s n u m b e r s (gross f o r m u las) of alkyl f r a g m e n t s a r e obtained for compound (I): 282-155 = 127 (CgHI9"), 282-169 = 113 (CsHI7'), 282183 = 99 (C7H15"), 282-225 = 57 (C4H9"), and 282-253 = 29 (C2H5"), and for compound (II): 116-59 = 57 (C5Hs') and 116-101 = 15 (CH3"). In the c o r r e s p o n d i n g oxygen-containing ions, the s e t of alkyl f r a g m e n t s should include the following r e s i d u e s : for (I)C~H~, C4Hs, C7H15, CsH17, CgH19, CiIH23, and for ( I I ) C H 3, C3H 7, C4H9, and C~H~3. Actually, c o n s i d e r i n g the m a i n p r i n c i p l e (the intensities of the p e a k s of s e r i e s 29) at the b a s i s of the selection of alkyl f r a g m e n t s , finally, this s e t should include the f r a g m e n t s C2H5, C4H9, C7ll15, C8H17, and CllH~3 for compound (I), and CH 3, C3H 7, and C6tt13 for compound (II). Thus, in the c a s e both of compound (I) and of compound (II), in a c o m p a r i s o n of s e r i e s 127 and 31, s e t s of alkyl f r a ~ n e n t s each containing one " e x t r a " m e m b e r Cone e r r o r ) a r e obtained. B. E s t a b l i s h m e n t of the Structural F o r m u l a of a Compound on the B a s i s of the Set of F r a g m e n t s O b tained. It was shown above that in the compilation of the-set of alkyl f r a g m e n t s by c o m p a r a t i v e analysis of the m a s s s p e c t r a , in c e r t a i n c a s e s it is i m p o s s i b l e to avoid e r r o r s , which leads to ambiguity of the s t r u c t u r a l f o r m u l a e s t a b l i s h e d . The a l g o r i t h m for the c o n s t r u c t i o n of the s t r u c t u r a l f o r m u l a should be r e l a t i v e l y insensitive to d i s t o r t i o n s in the set of alkyl f r a g m e n t s . The b a s i s of the p r o p o s e d a l g o r i t h m is the DENDRAI p r o g r a m [1], v a r i e d in such a way that only s t r u c t u r e s c o r r e s p o n d i n g to the set of alkyl f r a g m e n t s a r e generated. The d e g r e e of significance of s o m e i - t h i s o m e r i c s t r u c t u r e is d e t e r m i n e d by the quantity A = N i - Q i, where Ni is the n u m b e r of alkyl f r a g m e n t s f r o m the s e t u s e d in the c o n s t r u c t i o n of the i-th s t r u c t u r e ; Qi is the n u m b e r of alkyl f r a g m e n t s a b sent in the s e t , but additionally used in the c o n s t r u c t i o n of the i-th s t r u c t u r e . On account of p o s s i b l e e r r o r s in the set of alkyl f r a g m e n t s , the true f o r m u l a of the compound does not always c o r r e s p o n d to the m a x i m u m value of A. A n u m b e r of s t r u c t u r e s c o r r e s p o n d i n g to two (or three) g r e a t e s t values of A m u s t be taken into consideration, ~ The s t r u c t u r a l f o r m u l a sought is conveniently c o n s i d e r e d in the f o r m of an a g g r e g a t e of points on a plane, connected by s e g m e n t s of s t r a i g h t lines. Such a s y s t e m of connected points is called a graph. The points a r e called the v e r t i c e s of the g r a p h and r e p r e s e n t C and O a t o m s with the c o r r e s p o n d i n g n u m b e r of H a t o m s , while the s e g m e n t s connecting them a r e called the r i b s and r e p r e s e n t bonds between the a t o m s in the m o l e c u l e . The d e g r e e of a v e r t e x is d e t e r m i n e d by the n u m b e r of r i b s e m e r g i n g f r o m it and is equal to the valence of the a t o m situated in it, with a deduction of the n u m b e r of H a t o m s connected to it. In the depiction of the c h e m i c a l graph, the s y m b o l s of hydrogen a t o m s a r e usual!y omitted. F o r the c a s e of aliphatie alcohols (or t h e i r T F A ) , we can also o m i t the s y m b o l s for the c a r b o n a t o m s : C
C
C
C
C
C
C
C
0
O
2,4-Diethyl-octanol
F o r the construction of a c h e m i c a l graph of a p r i m a r y alcohol of known m o l e c u l a r weight (or its TFA) a c c o r d i n g to a set a g g r e g a t e of alkyl f r a g m e n t s , it is sufficient to c o n s t r u c t the graph of the i a r g e s t f r a g ment. The c o n s t r u c t i o n of the graph of the l a r g e s t alkyl f r a g m e n t is analogous to the construction of the i s o m e r i c s t r u c t u r e s of the c o r r e s p o n d i n g alkyl r a d i c a I s [1] and c o n s i s t s of s u c c e s s i v e selection of d e g r e e s of v e r t i c e s , begtm~ng with the v e r t e x with a f r e e v a l e n c e , followed by distribution of the r e m a i n i n g c a r b o n a t o m s along the r i b s of the graph. According to the p r o p o s e d a l g o r i t h m , the alkyl f r a g m e n t s of the given s e t a r e d i s t r i b u t e d along the r i b s of the graph. The p e c u l i a r i t i e s of the Mgorithm a r e m o s t s i m p l y d e m o n s t r a t e d in the e x a m p l e of the c o n s t r u c t i o n of a graph for the m o l e c u l e of the TFA of 2,4-diethyloetanol.
1448
TABLE 2. Results of the Establishment of the Structural Formulas of Primary Aliphatic Alcohols [8] and Their TFA Derivatives [6] on the Basis of Mass Spectra Using an Electronic Computer
Name
of compound
of set
' ~"~
Composition
,~
alkyl fragments
., "LINumber of varia~ Ikons obtamed ~ "~
CH3, C~Hs, C~H9 8 CH3, C~Ha, C4H9 17 C2H5, C3H7, C4H9 t7 CH3, C~Hs, CsH~, C4H~, C~Hn 8 CH3, C~I-I~, C~H7 3 - Methyl - 1-buta no1 t7 CH~, CsHT,CsHn 2-MethyI-l-pentanol 39 CH3, C3H~, C~Hg, C~H~ 2, 2-Dimethgl - l-pentanol 39 C3H~, CsHn, C6H13 5-Methyl-l-hexanol 89 C~Hs, C3H~, C~Hg, CsHn, 9 Cdt13, CTH~ 89 C3H~, C~H~, CsHn, CTH~ 2 -Ethy.1 - 1 - hexanol 3- Methyl-2-propyl- 1-pentano 1 2tt CH3 CsH~ 3, 5, 5 - T r i m e t h y l - l - h e x a n o l 21t CHz, C3H7- - CsH17 507 CH~, C~H~, C~H~,C~Hn, 2, 2 -Dimethyl - 1-octanol C~H~, CsHI~, C6H~ 2-Ethvl-l-oxtanol-TFA 89 CsH~, C~H~, C~H~ 2 , 4 - D i e t h y l - l = o e t a n o l - TYA 3067 C~H~, C~H~, C~H~, C8H~7, CsH~, Chris3 2 , 2 - D i l n e t h y l - l - n o n a n o l - T F A 1238 CH~, C~H~, C~Hn, C~Hm, CTH~, CmH~t 89 C~I-19, CsHlb C:H~5 2 - Methyl- 1-heptanol-T ~A 3067 C~Hg, C~Hn, C~H~, CsH~, 2-Methyl-l-undecanol-TFA
2, 2 - D i m e t h y l - l - p r o p a n o l
8
2 - M e t h y l - l - butanol 3-Methyl-l-pentanol 2,2 -Dimeth~rl - 1 - butano 1
-
-
C6H19, C~0H~, CuH~
~
t 0
4
2
1
t
--
2 2
2 3 7
1* 2* 4*
l t 3
----
t 0
t 4
t* 2*
-i
-t
t
1t
1
3 3 6 1t7
2 3
3
2
4 3 4
l 6*
8
[7": 33 78 ] 3 2r
9t
[9
0 I
5
1", 1"
3
2
[t
2 i 6 ]3
28
25"
24
5t *
3* 7 i~
t 20*
I
* The true structure is included in these isomers,
The construction of the structural formula of the largest alkyl fragment CiiH23 is begun from the vertex with the free valence. At the first stage the graph looks as follows: ill. The numbers next to the vertex mean that it is included in a fragment with ii carbon atoms. Such a vertex is called the terminal vertex. For primary alcohols the first terminal vertex can only be of thirdor fourth degree; therefore, two modes of further construction of the graph are possible, shown by arrows with the numbers 3 ~ and 4 ~ above them
A
A
F o r each of the two newly f o r m e d g r a p h s , a distribution of the alkyl f r a g m e n t s of the given set a m o n g the r i b s (with the e x c e p t i o n o f the r i b of the f r e e v a l e n c e ) i s r e q u i r e d , in s u c h a w a y that the s u m m a r y n u m b e r of c a r b o n a t o m s in t h e s e f r a g m e n t s i s equal to 1 1 - 1 = 10. T h i s c a n be done as f o l l o w s :
8
2
4
2
7
3
9
l
4
6
7
L
In the distribution of the alkyl fragments among the ribs of the graph, only one rib can be occupied by a fragment not contained in the given set. For this reason the following graphs are excluded:
8
|
4
$
and other similar ones. Any alkyl fragments of the given set can be used repeatedly. The construction of graphs of all the degrees of the first terminal vertex with distribution of the alkyl fragments of the set among the ribs of these graphs ends with this stage. The further stages are identical to the first. Beginning with the second stage, in the construction of the graph the vertices of second, third, and fourth degree are considered. In the case of graphs with vertices of the second degree, the only rib is filledby a small linear alkyl fragment contained in the set.
1449
As a r e s u l t of the construction, 54 graphs are obtained for the f r a g m e n t CllH23. The degree of r e liability of the graph of the true formula of the substance is estimated by the quantity A: A = 5-1 variation (true), A -- 4 - 7 v a r i a t i o n s , A = 3-15 v a r i a t i o n s , A = 2-18 variations, A = 1-12 v a r i a t i o n s , and A = 0-1 variation. Eight i s o m e r s with the following s t r u c t u r e s c o r r e s p o n d to the two l a r g e s t values: 2
2
2 2
2
7
2
4
I
!
H--,I
~1
-'-'o I
9
--~2
'_4 2
98
8
--~2
7
2
4
9 4~-----e!
1
7
2
7 ---*2
4
1
4
2
3
2
12
A c o n s i d e r a t i o n of the peculiarities of the m a s s s p e c t r o m e t r i c behavior of 2 - m e t h y l - s u b s t i t u t e d a l c o hols [6] p e r m i t s a reduction of the number of possible s t r u c t u r e s to three. Table 2 d e m o n s t r a t e s the r e sults obtained in the e s t a b l i s h m e n t of the s t r u c t u r a l formula for a n u m b e r of alcohols [8] a n d their TFA [6[ on the b a s i s of the m a s s s p e c t r a , using an electronic computer. As can be seen from Table 2, the significance of the r e s u l t s obtained is d e t e r m i n e d to a substantial degree by the n u m b e r of e r r o r s in the set of alkyl f r a g m e n t s used. One of the causes of these e r r o r s is an insufficient degree of purity of the s t a r t i n g m a t e r i a l o r standard sample. A loss of n e c e s s a r y alkyl f r a g m e n t s in the set may have different effects on the quality of the r e s u l t s . L o s s of the l a r g e s t f r a g m e n t does not p e r m i t e s t a b l i s h m e n t of the true s t r u c t u r a l formula of the compound. In the c a s e of loss of other f r a g m e n t s , the true v a r i a t i o n m a y also be lost. F o r example, the loss of CH~ in the c a s e of s t r u c t u r e s containing two methyl substituents at one carbon atom: a c c o r d i n g to the algorithm, only one rib of the graph can be filled by an alkyl f r a g m e n t not contained in the set. All this shows that in the d e t e r m i n a t i o n Of the d e g r e e of reliability of the s t r u c t u r e of the compound, it is n e c e s s a r y to consider not only the n u m b e r of alkyl f r a g m e n t s of the set used in the establishment of the s t r u c t u r e , but also the d e g r e e of their significance, which m a y be the subject of a s e p a r a t e investigation. The reliability of the r e s u l t s is i n c r e a s e d when additional information on the peculiarities of the m a s s s p e c t r o m e t r i c behavior of the investigated compounds is introduced into the a l g o r i t h m , as well as when s e v e r a l methods are used. If the r e s u l t of the use of the f i r s t method of i n t e r p r e t a t i o n of the given m a s s s p e c t r u m is s o m e multiple of A i possible i s o m e r s , the final number of possible i s o m e r s is d e t e r m i n e d by a multiple of A, which is the i n t e r s e c t i o n of the multiples of A i fh
A ----iAf Definite aid in the selection of the s t r u c t u r a l f o r m u l a of a number of possible i s o m e r s can be r e n d e r e d by the use of gas c h r o m a t o g r a p h i c p a r a m e t e r s of the investigated compounds. CONCLUSIONS 1. An algorithm of the e s t a b l i s h m e n t of the s t r u c t u r e of molecules of higher p r i m a r y aliphatie a l c o hols using only m a s s s p e c t r o m e t r i c data was described. In the c o n s t r u c t i o n of possible s t r u c t u r a l f o r m u l a s , the predominant cleavage of C - C bonds in e l e c t r o n impact at sites of branching of the carbon chain is c o n sidered. 2. A c o m p a r a t i v e method was p r o p o s e d for the analysis of the m a s s s p e c t r a for the detection of c a s e s of cleavage of the h y d r o c a r b o n chain at sites of branching. 3. The n u m b e r of s t r u c t u r a l v a r i a t i o n s obtained using the p r o p o s e d algorithm can be significantly r e duced by the s u p p l e m e n t a r y use of information on the peculiarities of the m a s s s p e c t r o m e t r i c behavior of i s o m e r i c compounds of a definite type.
LITERATURE io
2.
1450
CITED
V. G. Buchanan, A. M. Duffield, and A. V. Robertson, Mass Spectrometry: Techniques and Applications, Wiley-Interscience, New York (1971), p. 121. A. Buchs, A. B. Delfino, A. M. Duffield, C. Djerassi, B. G. Buchanan, E, A. Feigenbaum, and J. Lederberg, Helv. China. Acta, 533, 1394 (1970).
3o
4. 5. 6.
7. 8.
A. Buchs, A. B. Delfino, C. Djerassi, A. M. Suffield, B. G. Buchanan, E. A. Feigenbaum, J. Lederberg, G. Sehroll, and G. L. Sutherland, Advances Mass Spectrometry, 5, 314 (1971}. G. Schroll, A. M. Duffield, C. Djerassi, B. G. Buchanan, G. L. Sutherland,-E. A. Feigenbaum, and J. Lederberg, J. Amer. Chem. Soc., 91, 7740 (1969}. F. W, McLafferty, Mass Spectrometry of Organic Ions, Academic Press, New York (1963}, p. 364. B. V. Rozynov, N. S. Vul'fson, I. A. Bogdanova, G. I. Spivakovskii, I. I. Zaslavskii, and A. I. Tishchenko, Izv. Akad. Nauk SSSR, Ser. Khim., 1522 (1974}. R. A. Friedel, J. L. Shultz, and A. G. Sharkey, Analyt. Chem., 28, 926 (1956}. E. Stenhagen, S. Abrahamson, F. W. McLafferty, Atlas of Mass Sp---ectral Data, Wiley4nterscience, New York (1969}.
1451
