The ester acids necessary for studyng the thermochemical properties of pyromellitic acid (PMK)-based peroxides were investigated. Obtaining a tetramethyl ester of a PMK was described. The mechanism of an esterification reaction is discussed, as is the complete esterification of PMK with primary alcohol

Donchak, V. A.

Fedorova, V. A.

Martynyuk-Lototskaya, A. N.

English

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NASA TECHNICAL MEMORANDUM NASA TM-77977
SYNTHESIS OF PYROMELLITIC ACID ESTERS
V. A. Fedorova et al.
{N&SA-TH-77977) SYNTHESIS OF PYBOMELLITIC N86-21583
iACID ESTEBS (National Aeronautics and Space
Administration) 6 p HC &02/flF &01 CSCL 07C
ttnclas
G3/23 05711
Translation of "sintez efirov piromellitovoy kisloty," Visnik
1'vovskogo politekhnicheskogo institut (Journal of the L'vov
Polytechnic Institute), Vol. 139, 1980, pp. 31-33 (ISSN
0460-0436) (UDC 547.585.26)
MAR1986
?§ RECEIVED
-«-*
~c>
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
WASHINGTON, D.C. 20546 DECEMBER 1985
https://ntrs.nasa.gov/search.jsp?R=19860012112 2020-03-20T14:59:57+00:00Z
S T A N D A R D T I T L E PAGE
1. Report No.
NASA TM-77977
3. Co 3. R«cipi*nt • Coto)op KG
•<. Till, one! Subti t le SYNTHESIS OF PYROMELLITIC ACID
ESTERS
5. R«p»'i Dot*
^December 1985
6. Performing Oiponiietion Coo**
7. AutKor(i) 6. P.rfoiminp Orpomiot jon Rvpor l No
V. A. Fedorova et al.
10. Work Unit No.
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National Aeronautic and Space Administration
Washington, DC 20546 4. Sponiorinp Apvncy Coric
is. Suppi.mcntory NOI.I Translation of "'sintez efirov piromellitovoy kisloty,"
Visnik 1'vovskogo politekhnicheskogo institut (Journal of the L'vov Polytechnic
Institute), Vol. 139, 1980, pp. 31-33 (ISSN 0460-0436);(UDC 547.585.26).
. Abn.oei This article studies the efeter. acids;jnecessary for studying the thermo
chemical properties, of pyromellitic acid (PMK)-based peroxides. It covers
obtaining a tetramethyl ester of a PMK. The mechanism of an esterification
reaction is discussed, as is the complete esterification of PMK with primary
alcohol. ' .
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 2
SYNTHESIS OF PYROMELLITIC ACID ESTERS
V. A. Fedorova, V. A. Donchak, A. N. Martynyuk-Lototskaya
When studying the thermochemical properties of pyro- /31»
mellitic acid (PMK)-based peroxides, it was necessary to obtain
complete and n-alkyl ester acids for this acid.
A tetramethyl ester of a PMK is obtained by acylation of
alcohols PMK in an air-fluidized bed in the presence of special
catalysts [2], in a liquid phase—in the presence of a
concentrated sulphuric acid [1] during the interaction of
pyromellitic dianhydride (PMDA) with dimethyl sulphite at
110-120°C [3].
The mechanism of an esterification reaction, as it is known,
corresponds to the following arrangement: primary protonization
of a carboxylic acid for the formation of active particles of
electrophilic nature which combines the nucleophilic alcohol with
the formation of a secondary oxonium ion. This induces the
migration of a proton from alkylated oxygen to hydroxyl with the
splitting of a water molecule and the formation of a complex
ester. The reactivity of anhydrides is higher than that of
carboxylic acids; therefore, the reaction of esterification
proceeds with a quantitative yield without the protonization of
an anhydride, usually in an excess of alcohol. According to
acylating activities, even the acetic anhydride exceeds PMDA.
Therefore, the acids of methyl and ether esters were obtained by
acylation of suitable alcohols for PMK in a multiple excess of
alcohol (usually 20 moles of alcohol for one mole of PMDA) for
homogenizing the reaction medium and for completeness of the
^Numbers in the margin indicate pagination in the foreign text.
ORIGINAL PAGE !S
OF POOR QUALITY
acylation reaction at the boiling temperature of a reaction
mass. I and II with a yield of 97.8 and 96.7*, respectively, are
obtained by using these methods. The acylation reaction rate of
n-propyl alcohol is noticeably decreased as a result of the
decrease of its nucleophile; therefore, there is a difference in
the activity of two reaction centers of PMDA in relation to
n-propyl alcohol. For this reason, after an hour's contact with
the reagents, a product of half-esterification of Ilia (80%) is
obtained and only 20% of an acidic di-n-propyl ester of PMK (III)
is as follows
0 0 o
1 I •
C-0 Cji, C,h,-D .',
C - o n HO-C <Z>* C-Ot!
t i >
0 ' 0 0
II. a
Further esterification of Ilia was reached by an addition to /32
the reaction mass of catalytic quantities of pyridine.
Complete esterification of PMK with primary alcohol prior to
the tetraalkyl esters occurs when the reagents are dissolved in
concentrated sulphuric acid. The mechanism of this reaction
includes two stages: the formation of acids of dialkyl esters of
PMK and then the protonization of carboxyl groups which appeared
with a nucleophilic substitution for alkoxy groups according to
the arrangement
CO ' ' -: ~*OC COOtt t t O O C ^ COOH
*^T6rr* -*_"??_ ^.^-^*
M-C. , t-OH -^>° eooc'^~ COM
0 ' 0
ORIGINAL PAGE !S
OF POOR QUALITY
In proportion to the increase of a hydrocarbon radical, a
steric hindrance occurs in the alcohol, the reaction rate is
reduced, and the product yield is decreased. Thus, IV is
obtained by this method with a yield of (97.2%), V—94.4%, and
VI —91.7%.
Products I—III are crystallized out by diluting the reaction
mass with a 5% solution of HC1. These products (I-III) were
purified by recrystallizations from suitable water alcohols and -
then dried in a vacuum. Tetraalkyl pyromellitic IV-VI were
crystallized out when the reaction mass was diluted with ten
units of cold water. The precipitated crystals were filtered out
and purified by the recrystallizations of water alcohols.
Synthesized esters were identified by the boiling temperature or
by the melting and element analysis (see table).
Character is t ics of di- and t e t r a a l k y l pyronel1 itic esters
11
Esters T'.C
Reac-
tion
time ,
hours
Yield
Z
Melting
temp.
( Boiling
temp. ) ,
Found
C, Z K. ch'.*
mg KOH/g Formula
Calculated
C, t K. ch.*
mg KOH/g
D i m e t h y l pyro-
•el l i t ic ( I )
D i e t h y l pyro-
•el l i t ic ( I I )
D i p r o p y l pyro-
M e l l i t i c ( I I I )
66 0.5 97.8 271 51.01 398.0 CnHaO t 51.07 397'.6
i
80 C.5 V6.7 219 51.22 361,2 ^q, 5<«.'l9 361.6
95 0,5 92.1 112 56,71 333.7 C^H^o, 56.79 331.1
Tet ra«e thy l pyro- IC3 2,0 97,2 III 51,12 - C K 0 51,19
M e l l i t i c ( I V ) " * '
Te t rae thy l pyro- 122 2.0 91,1 56 55,98 - ' ^ H,, 0, '59.01
M e l l i t i c ( V ) /
62,53
2,0 91,7(212/0.65
»^l 1 meters of
" Me"rcury c o l u m n )
•Translator 's note: K. ch. «ay be Curie un i t .
62.53 -
It is apparent from the table that by increasing the /33
hydrocarbon radical of an alkoxyl component, a decrease in the
melting temperature associated with the increase in the volume of
a molecule takes place. Acid esters have a higher melting
temperature and are more easily crystallized than tetraalkyl
pyromellitic esters.
REFERENCES
1. Nazarov, N. N., Samenovskiy, A. V. "Khlormetilirovania
toluola" [Chloromethylation of Toluene], Proceedings from the
Academy of Science of the U.S.S.R., Department of Chemical
Sciences, 1956, No. 12, pp. 1487-1492.
2. Benning I., Novotny R., Patent 37630 (German Democratic
Republic), "Sposob polucheniya efirov karbonovykh kislot" [A
Method for Obtaining Esters of Carboxylic Acid], published
07/06/65.
3. Patent 104299 (Holland), "Sposob polycheniya slozhnykh efirov
vzaimodeystviem angidridov so spirtami v prisutstvii
sernistoy kisloty" [A Method for Obtaining Complex Esters by
the Interaction of Anhydrides with Alcohols in the Presence
of Sulphurous Acid], published 04/06/63.
The article was received by the editorial staff on May 16, 1979.


Synthesis of pyromellitic acid esters

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