Lee H Horsley Azeotropic Data-III

Azeotropic Data—III

In Azeotropic Data—III; Horsley, L.; Advances in Chemistry; American Chemical Society: Washington, DC, 1973.


Azeotropic Data—III

Compiled by Lee H . Horsley

The Dow Chemical Co.

Midland, Mich.

ADVANCES I N CHEMISTRY SERIES 116

AMERICAN CHEMICAL SOCIETY

WASHINGTON, D . C . 1973


ADCSAJ 116 1-628 (1973)

Copyright © 1973

American Chemical Society

All Rights Reserved

Library of Congress Catalog Card 73-75991

ISBN 8412-0166-8

PRINTED IN T H E UNITED STATES OF AMERICA


Advances in Chemistry Series

Robert F . Gould, Editor

Advisory Board

Bernard D. Blaustein

Paul N . Craig

Ellis K. Fields

Louis Lykken

Egon Matijević

Thomas J. Murphy

Robert W . Parry

Aaron A. Rosen

Charles N . Satterfield


FOREWORD

ADVANCES IN CHEMISTRY SERIES was founded in 1949 by the

American Chemical Society as an outlet for symposia and collections of data in special areas of topical interest that could not be accommodated in the Society's journals. It provides a medium for symposia that would otherwise be fragmented, their papers distributed among several journals or not published at all. Papers are referred critically according to ACS editorial standards and receive the careful attention and processing characteristic of ACS publications. Papers published in ADVANCES IN CHEMISTRY SERIES are original contributions not published elsewhere in whole or major part and include reports of research as well as reviews since symposia may embrace both types of presentation.


PREFACE LEE H. HORSLEY ix-x 1 Tables of Azeotropes and Nonazeotropes 1-613 Table I. Binary Systems 3 Table II. Ternary Systems 448 Table III. Quaternary Systems 496 Formula Index 503 Bibliography 589 2 Prediction of Azeotropism and Calculation of Azeotropic Data 615-622 3 Vapor-Liquid Equilibrium Diagrams of Alcohol-Ketone Azeotropes as a Function of Pressure E. C. BRITTON, H. S. NUTTING, and L. H. HORSLEY 623-625 4 Graphical Method for Predicting Effect of Pressure on Azeotropic Systems H. S. NUTTING and L. H. HORSLEY 626-628

Table of Contents

PREFACE

his volume is a complete revision of Azeotropic Data I and II pub-± - lished as ADVANCES IN CHEMISTRY SERIES NO. 6 and No. 35, American

Chemical Society. It includes revised data on systems in the original tables plus new data on azeotropes, nonazeotropes, and vapor-liquid equilibria collected since 1962.

No attempt has been made to evaluate the accuracy of the data. Where appreciable differences occur in the data from a single investigator, only the most recent data are recorded. Where differences in values from two different sources occur, both sets of data are recorded. To aid the reader in evaluating data on a given system, however, all references to that system are included.

In general, data have been obtained from the original literature. Where the original litereature was not available, data have been taken from Chemical Abstracts. In a few instances, data have been taken from collections of azeotropic data in handbooks, review articles, and so forth.

The tables are arranged in the same manner as the previous volumes. This is based on empirical formula as in Chemical Abstracts except that all inorganic compounds are listed first, alphabetically by empirical formula.

For a given binary system the lower order component according to empirical formula is chosen as the Α-component, and under each A-com-ponent the B-components are also arranged according to empirical formula. For ternary and quarternary systems, the same arrangement is used, using the lowest order formula as Α-component, the next lowest order as B-component, and so on.

Abbreviations

max. b.p. Maximum boiling point azeotrope (negative azeotrope) min. b.p. Minimum boiling point azeotrope (positive azeotrope) atm. Pressure in standard atmospheres mm. Pressure in millimeters of Hg p.s.i.a. Pressure in pounds per square inch absolute p.s.i.g. Pressure in pounds per square inch gage v-1 Vapor-liquid equilibrium data are given in the original

v.p. reference Vapor pressure

ix


vol. % Azeotropic concentration is given in volume per cent. Unless so indicated, all concentration data are in weight %

r-> Approximate >, < Greater than, less than

While all volumes in this series, "Azeotropic Data," are collections of data, mostly from the literature, the supplement that was published as No. 35 in the Advances in Chemistry Series included previously unpublished data from industrial files, of which most was from Union Carbide Chemicals Co., assembled by William S. Tamplin. Additional contributions came from Commercial Solvents Corp., Eastman Chemical Products, Inc., Farbenwerke Hoechst, Imperial Chemical Industries Ltd., and Minnesota Mining and Manufacturing Co. These data are continued in the present volume.

Special thanks go to David C. Young for his invaluable work on this volume.

The Dow Chemical Co. L E E H. HORSLEY Midland, Mich. November 1972

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BIBLIOGRAPHY 613

(1061) Zieborak and Galska-Krajewska, Bull. Acad. Polon. Sci., Classe III 7, 253 (1959); C.A. 54, 16068 (1960).

(1062) Zieborak, Kaczorowna-Badyoczek, and Maczynska, Roczniki Chem. 29, 783 (1955); C.A. 50, 6119 (1956).

(1063) Zieborak, Maczynska, and Maczynski, Roczniki Chem. 32, 85 (1958); C.A. 52, 12493 (1958).

(1064) Zieborak and Maczynska, Roczniki Chem. 32, 295; C.A. 52, 17862 (1958).

(1065) Zieborak and Markowska-Majewska, Bull. Acad. Polon. Sci., Classe III 2, 341 (1954).

(1066) Zieborak and Olszewski, Bull. Acad. Polon. Sci., Classe III 4, 823 (1956); C.A. 51, 7789.

(1067) Zieborak and Wyrzykowska-Stankiewicz, Bull. Acad. Polon. Sci., Classe III 6, 377 (1958); C.A. 52, 19392.

(1068) Zieborak and Wyrzykowska-Stankiewicz, Bull. Acad. Polon. Sci., Classe III 6, 517 (1958); C.A. 53, 3875 (1959).



(1071) Zieborak and Zieborak, Bull. Acad. Polon. Sci., Classe III 2, 287 (1954); C.A. 49, 2803.

(1072) Zilberman, J. Appl. Chem. U.S.S.R. 26, 809 (1954). (1073) Zmaczynski, Roczniki Chem. 11, 449 (1931); C.A. 25, 5809. (1074) Zorin, Devyatykh, Krupnova and Krasnova, Zh. Neorgan. Khim. 9, 2280 (1964);

C.A. 62, 2261. (1075) Zvaritskaya and Delarova, Tr., Vses. Nauchn.-Issled. Alyumin.-Magnievyi Inst. 1961,

96; C.A. 57, 2914. (1076) Zvaritskaya and Delarova, Tr. Vses. Nauchn.-Issled. Alyumin.-Magnievy Inst. 1962,

152; C.A. 59, 12235.


Prediction of Azeotropism and

Calculation of Azeotropic Data

Whether or not a system of two compounds is azeotropic depends essentially on two factors: (1) the difference in boiling point of

the two components, and (2) the degree to which the two components form an ideal system. The closer the boiling points of the two components are, the more likely that they will be azeotropic; the more ideal the solution of the two components is, the less likely that they will form an azeotropic system.

The ideality of a two-component system depends largely on the difference in certain physical properties of the components such as polarity, degree of association, tendency toward hydrogen bonding, etc. When the two components are similar—e.g., two hydrocarbons or two alcohols —there is little tendency toward azeotropism. However, if the two components are markedly dissimilar—such as an alcohol and a hydrocarbon— they tend strongly toward azeotropism.

By taking account of the above factors it is sometimes possible to predict azeotropic data fairly well. For example, the departure from ideality of a series of solutions of methanol with hydrocarbons will be relatively constant. As a result the tendency for a methanol-hydrocarbon system to be azeotropic will be related to the other factor, the difference in boiling point. As a result the lowering of the boiling point ( designated δ) and the azeotropic composition will be related to this difference in boiling point. Therefore we can predict δ and azeotropic composition for any methanol-hydrocarbon system from the boiling point of the hydrocarbon.

This procedure is the basis for the series of relations shown in Figures 1-6 which can be used to predict azeotropic data for related systems. The procedure also indicates the effect of pressure on azeotropic composition if one determines the difference in boiling point of the system at any desired pressure and applies the data to the appropriate curve. This is illustrated in Figure 6.

In the special case where the two components are immiscible, it is possible to calculate azeotropic boiling point and composition to a high degree of accuracy. For such a system the total vapor pressure is equal to the sum of the vapor pressures of the two components at a given temperature. Therefore, from a plot of vapor pressures of the two com-

615


616 AZEOTROPIC D A T A

ponents it is possible to determine the temperature at which the sum of the component vapor pressures is equal to 760 mm. This temperature will be the azeotropic boiling point. The azeotropic boiling point can be determined at any other pressure in a similar manner.

Further, the azeotropic composition can be calculated from the expression:

V A X 100 Mole % A =

V A + V B

where V A + V R are vapor pressures of A and Β at the azeotropic boiling point.


Prediction of Azeotropism 617

METHANOL-HYDROCARBONSH

t~ PROPANOLS—lHYDRO--ALLYS ALCOHOL j CARBONS

0 20 40 60 80 100^120 0 20 40 60 80 Ι00| Δ |Ι2) 0 10 20 30 40 50|A|60

: I : I METHANOL- HYDROCARBONS

q F4 -4 4- 1-4 J

ETHANOL- HYDROCARBONSH

40h

40 80Δ120 -120-80 -40 0 40 80Δ120

8

~>>

ISOAMYL ALCOHOL DIETHYL CAR'BINOL—

8

~>> WDR OCAR BONÎ

8

~>> WDR

0 10 20 30 40 50|Δ (60 c " " "

10 20 30 40 50|Δ|60

-60-40 -20 0 20 40 Δ 6 0 -60-40 -20 Ο 20 4 0 Λ 6 0 -60-40 -20 Ο 20 40 Δ 60

4 Γ " J6LYC0L-

HYDROCARBONS

20 40 60 80 ΚΧ>|Δ|Ι20 Ο 20 40 60 80 100 120

40

Ο

16

12

8

4

Ο.

c •••Ι \ - Ϊ Ί ._ _ GLYCEROL

ΗΥ DROC ARBC NS -

10 20 30 40 50|Δ)60

-120-80 -40 Ο 40 8 0 Δ Ι 2 0 120 80 40 Ο 40 8 0 Δ Ι 2 0 -30 - 20 -10 10 20 Δ 30

Figure 1. C-Δ and δ-|Δ| curves for alcohol-hydrocarbon, glycol-hydrocarbon, and phenol-hydrocarbon systems

C: Azeotropic composition in weight % first component δ: Boiling point of lower boiling component minus azeotropic boiling point

|A| : Absolute difference in boiling points of components A: Boiling point of first component minus boiling point of second component


618 A Z E O T R O P I C D A T A

s 1 1 1 1 1 -ORE :sou >-HY DRGK ARB( )NS-

ι 1 · I i"- 1

δ 1 1 1 ι ι I

DVDAr.ATCrUlM NS-V πτυπυυ* NS-

\ ν

1 1 l . _

δ 1 1 1 RFQnpr.iiuni

NS-Π Ι Ι NS-

1 1 10 15 2 0 2 5 I A 1 3 0 0 10 2 0 3 0 4 0 5 0 ^ , 6 0 0 10 2 0 3 0 4 0 5 0 ^ 6 0

1ΙΔΙ

100 8 0 [

4 0

0_

32,

2 4

16

8

Q

c ! ! 1 1 1 -ORE :sou >-HY DRO( ÎARB )NS-

. . J I

4 0

c 1 ! 1 D V D n r . A T c r u i M

nTUKUOAKDUNb

1 1 1 1 1 3 0 - 2 0 -10 0 10 2 0 Δ 3 0 - 3 0 - 2 0 -10 0 10 20 Δ 3 0 - 3 0 - 2 0 -10 Ο 10 2 0 Λ 3 0

Μ ι ι 1 1 1 Γ Λ Ο Μ Ι Λ Α Λ Ι Π Γ

iARB ONS-Πι υ nu iARB ONS-

I I I ι 1

s | I I 1 1 1

HV J C I n J H U I υ

M B ( N S -Π! U M B ( N S -

1 I -1 1

" Τ Ί — I — I 7 PROPIONIC ACID Γ BUTYRIC ACID VALERIC ACID.

HYDRO-— CARBONS

100

8 0

4 0

0 —I

16

12

8

4 0

c 1 j j C A D U i r Α Λ Ι Π

ARB )NS-S. Π1 unui ARB )NS-^. *

1 1 _ _ L _ 1 ..1 1

c 1 1 1 Η U t l 1 U HUI U

ARB )N8-X H

ΠΤΙ ARB )N8-

1 _ l 1 1 1 1

100 801

4 0

PROPIONIC ACID, BUTYRIC ACID

6 0 - 4 0 - 2 0 0 20 4 0 A 6 0 - 6 0 - 4 0 - 2 0 0 2 0 4 0 Λ 6 0 - 6 0 - 4 0 - 2 0 0 20 4 0 Λ 6 0

s ι ι ι ι ι METHANOL-HALI DE

>HI\D\

• κ I ι I

I I I - ΕΤΗ ANOL- HALIDE

π I

• ι i • 1

PROPANOLS-HALIDE HYDROCARBONS

4 0

0 6 0 - 4 0 - 2 0 0 2 0 4 0 Δ 6 0 - 6 0 - 4 0 - 2 0 Ο 2 0 4 0 Δ 6 0 - 6 0 - 4 0 - 2 0 Ο 2 0 4 0 Δ 6 0

Figure 2. C-Δ and δ-|Δ| curves for phenol-hydrocarbon, acid-hydrocarbon, and alcohol-halide hydrocarbon systems



' δ 1 1 1 1 BUT WOLS-HALIDE

π unu OMKD \

Ν —1— V 1 1

~ Γ Ί ι ι ISOAMYL ALCOHOL TERI AMYL ALCOHOL

Ο 10 20 30 40 50 l A l60 0

100 801

40|

0_

32

24

16

8

Q

c I 1 1 1 -BUT ANOLS-HALIDE—

π •

1 1 I

HALI DE-HYDROCARBON

δ 1 1 1 1 1 ( :YCL( )XANOL-HLIDE

ΠΙ

1 m 1 t I

40

c

PENT ANOLS-HALIDE—

v • π τ

\ s, ν» -, 1 ?» ttl

c I 1 I J I -CY CLOI HEXA NOL-HALIDE-

YDROCARBONS-ν . Η

NOL-HALIDE-YDROCARBONS-

\ \ V I ι I \ ι I

-60-40 -20 Ο 20 40 Λ 60 - 60 -40 -20 Ο 20 40 Δ 60 -60-40 -20 Ο 20 40 Δ 60 Ι6Γ δ I I I I ! I

ΌΧ

HYDROCARBONS"

I Ι •S4i I 1 0 10 20 30 40 50 60 0 5 ΙΔΙ

1 1 1 -PHE :NOL -HALI DE

MTUKUl /AnDUNο

._.l 1 1 1**

δ 1 1 1 1 CRE SOLS-HALI D E —

ΠΤ AnD

1 1 - J — ι •

100 80

40

°_

16

12

8

4

0

c 1 1 1 1 1 1

r i v / V M L I A I inc MYUnU

• 1 1 1 •"7*

c 1 1 1 nucMni U A I inc NS-ΠΤΙ An DA. NS-

_. 1 1 I 1

100 80

40

c 1 I I 1 -CRI ESOLS-HI

u v r Î D n r tLi DE

> Ν

1 1 s*. 1

δ 1 1 1 1 1 ^ P rRoc ATE( :HIN-HAUDE-

)ROCARBÔNS-HYC :HIN-HAUDE-)ROCARBÔNS-

1 1 ι 1

δ 1 — F )RMI C AC

HYDf ID — h *OCA

IALIDE — RBONS-v

C AC HYDf

ID — h *OCA

IALIDE — RBONS-

\ • X 1 Scr. . ι 1

' δ ι ι ι ι ι

V CETIC ACID-HALIDE—

HYDROCARBONS

\ v 1 ι ι

100 80

40|

Ο

c I I I I I — Ρ ROC ATEC HIN-HALIDE—

ROCARBONS-HYD HIN-HALIDE— ROCARBONS-

ι ι ι ι I

100 80

40

c I I I I I — F OR Μ C ACID-HALIDE—

HYDROCARBONS-C ACID-HALIDE— HYDROCARBONS-

• ι ι 1 I · I*

80

40

ACETIC ACID-HALIDE-HYDROCÀRBONS"

-30-20 -10 0 10 20 Λ 30 -60-40 -20 0 20 40 Λ 60 -60-40 -20 Ο 20 40 Δ 60

Figure 3. C-Δ and δ- |Δ| curves for alcohol-halide hydrocarbon, glycol-halide hydrocarbon, phenol-halide hydrocarbon, and acid-halide hydrocarbon systems



δ I 1 1 . [ .PRO .BUT .VAL

PIONI ÏRIC :RIC

C AC ACK ACIE

HALI HYDf CAR!

DE-10--30NS

1 ^ „ •

my ANO --ES TERÎ

•

0 ί ) 10 15 2 0 2

δ ETW iNOL -ES" ERS

• • •

Π C ; ι η ι R 7

100 80

40

q 16

12

8

4

Ο,

PROPIONIC ACID_ BUTYRIC ACIDlL VALERIC A C I D L :

HALIDT "HYDRO-"

_CARBON~

100 80

Η 40

C 1 1 1 1 1 — γιεπ ANO -ES TERÎ

•

c ΕΤΗ \NOL -ESI "ERS

•

-60-40 -20 Ο 20 40 Δ 6 0 -30-20 -10 Ο 10 20 Α 30 -30 -20 -10 Ο 10 2 0 Δ 30

Ι6 | — τ — ι 1 ι 1 1 1 Ι 6 Γ δ I I I I I —f ROPI WOL S-E< ITER

• ι ^ ο,

δ ÎUTA NOLS -ES TERÎ

δ ESTE RS-I OA NOLS

0 5 10 15 20 25|Δ !30 0 5 10 15 20 25 | Δ (30 0 5 10 15 20 25 | Δ |30

100 80

40

Ο

16

12

8

4

Ο

C — ρ — Α

ROPA 1YL

NOLS ALCC )HOL j-ES' ERS

V \

δ I I I A l v r . n i - C C T C D C

•

.. -I I

100 80

40

Ο

32,

C

BUTA NOLS -ES" ERS >

χ . • s L

V s..

M l fii v r . r o m _ c c fERS fERS

0 10 20 30 40 50|Δ|60 0 10 20 30 40 50,A,60 0 5 10 15 20 25|A,30 C

-GU COL- EST :RS- —

1 1—

100 80

40

C 1 1 1

100 80[

40

C

PMF N0L< -ES" ERS r n t N0L< -ES" ERS

•s s. -60-40 -20 0 20 40 A 60 -60-40 -20 0 20 40 .60 -30-20 -10 0 10 20 A 30

Figure 4. C-A and δ- |Δ | curves for acid-halide hydrocarbon, alcohol-ester, glycol-ester, and phenol-ester systems



δ 1 1 \ METHANOL )

ETHANOL 1 PROPANOLS -f

1 1 \ METHANOL )


1 1 \ METHANOL )


-ΕΤΗ ÎRS-

BUI* INUL

1 I

δ I I ι I HEXAN0LS

* UCDTAMAI c •ETHERS"

ι I _1 ι

δ I I I ι ι ι t i r

1 Γ* 5 ι ι Ό 10 20 30 40 50 ) Δ|60 Ο 5 10 15 20 25 ) δ|30 Ο 20 40 60 80 100, 120

Ι00| 80

40|

Ο

c ι ι ALC( IH0L δ - Ε ' 'HER > —

ι ι ι

40

c 1 1 Ί

HEXANOLS HEPTANOLS

>ETr ERS-

ι 1 I J.

c

COL--ETH CDC ο LI COL--ETH

1 1 I 1 1 -30 -20 -10 0 10 20 Δ 30 -30 -20 -10 0 10 2 0 Δ 3 0 -60-40 -20 Ο 20 4 0 Δ 6 0

32

24

16

8

Ο'

δ I I I I I -WA TER- ΕΤΗ ERS, ACET ALS-

1 1 1 ι

δ I I I I fiivrni νcTAUce

ι 1 1

16, s i I I — WLS -PHI NOL >

• ι ·

"\ C : ι η ι ι

κ η η ο I Ο 20 40 60 80 Ι00|Δ|Ι20 Ο 20 40 60 80 ΙΟΟ|Δ)Ι23 Ο 5 10 15 20 25 (Δ|30

100 80

40

°_

16

12

8

4

Ο:

c

-WA 'ER- ΕΤΗΙ :RS, ACET ALS-

ι ,ι ι ι

100

40

c I I I GLY< 0L- ΚΕΤ( NES

I ι ι ι

ο ι ι ι ι ι

1 iLCO HOU - Ρ Η EN0L S—

ν ν Ν

ι . ι _ L _ -60-40 -20 Ο 20 40 Δ 60 -60-40 -20 Ο 20 40 Λ 60 -30-20 -10 Ο 10 2 0 Α 3 0

δ 1 1 'ΗΕΚ 0LS--ΚΕΤ ONE;

, ι > •

δ I I i MOI WLS -ΚΕ- ΟΝΕ

r

ι . I ' rv ι ι

κ η

ι ι/Λ Ο Ό 5 10 15 20 25|Δ|30 Ο 5 10 15 20 25 Μ 30 Ο 5 10 Γ ΊΔΙ3

« I I ι ι

- Η ιΤΤΥ ACI )S-I THE RS-

Ν. \ ι ι 6 ί > Γ 0 1 5 2 0 2 « 1 . 1 *

100 80

40

Ο

c I I I I I — PHEh 0LS--ΚΕΤ ONE;

I * ι ι ι I

100 80

40

c I I I —ι 1C0I 40LS -ΚΕ" ΟΝΕ 5—

V \ C

ι I \ ι

100 80

40

c I I I ι

—Fi Π7Υ ACIC S-E' "HER S—

• •

•

ι 1. I ι " Τ -30-20 -10 Ο 10 20 Λ 30 -60-40 -20 Ο 20 40 Λ 60 -60-40-20 Ο 20 40 Α 6 0

Figure 5. C-Δ and δ- |Δ| curves for alcohols-ethers, glycols-ethers, water-ethers, acids-ethers, alcohols-ketones, glycol-ketones, alcohols-phenols, and

phenols-ketones



loo 1

80

40|

0

c M ΠΉΑί 1 I 1

40L- HYDROCARBONS ~ Ch

1 1 teOH CeHe -

2C

1 1 teOH CeHe -

ι

100 80

-120-80 -40 0 ι r

40

ol

r ι METHANOL-HALOGENATED"

HYDROCARBONS "CH3OH ' e c u -

275 700 mm ~

-60 -40 -20 0 20 40 Δ 60 c I I I T

ETHANOL-HALOGENATED | HYDROCARBONS

-120 -80 -40

100 801

40

c 1 1 1 1 1 PROPA NOLS-HY DROCARBONS C3H7OH CeHe _

100 8.000 mm. C3H7OH CeHe _ 100 8.000 mm.

(ALCOHOL-' KE NEs]—— CH3OH CH3COCH3 CH3OH CHsCOCeHe ΟζΗδΟΗ CH3COC2H8

-l-CzHeOH CH3COC3H7 100 14,000 mm.

-120-80-40 0 40 80 Δ Ι20 -40-20 0 20 40 60 Δ 80

Figure 6. C-Δ curves for alcohol-hydrocarbons, alcohol-halide hydrocarbons, and alcohols-ketones

Curves show agreement with experimental data at various pressures

C: Weight % alcohol Λ hydrocarbon Δ: Boiling point of alcohol minus > halide hydrocarbon

boiling water ) ketone


Vapor-Liquid Equilibrium Diagrams of Alcohol-Ketone Azeotropes as a Function of Pressure

E. C. BRITTON,1 H. S. NUTTING, and L. H. HORSLEY

The Dow Chemical Co., Midland, Mich.

Pressure has a marked effect on the azeotropic composition and vapor-liquid equilibrium diagrams of alcohol-ketone systems (1). This is due to the fact that the slopes of the vapor pressure curves of alcohols are appreciably greater than for ketones; it results in an unusually large change in the relative boiling points of the components of an alcohol-ketone system with change in pressure.

As a result of the study of these systems, it has been found that the methanol-acetone azeotrope exhibits the unusual phenomenon of becoming nonazeotropic at both low and high pressures—that is, below 200-mm. pressure the system is nonazeotropic with methanol as the more volatile product, while above 15,000 mm. the system is nonazeotropic with acetone the more volatile component.

Some of the equilibrium data for this system and two other alcohol-ketone azeotropes are shown in Figures 1 and 2 on the following pages.

The similarity of the diagrams for the different systems at suitable pressures is of interest. For example, the diagram for methanol-acetone at 10,000 mm. corresponds approximately to the diagram for methanol-methyl ethyl ketone at 1000 mm. and for ethanol-methyl propyl ketone at 100 mm.

Literature Cited (1) Britton, E. C., Nutting, H. S., Horsley, L. H. U.S. Patent 2,324,255 (July

13, 1943).

1 Deceased.

623


624 A Z E O T R O P I C D A T A

200,

METHANOL- ETHANOL-METHANOL METHYL ETHYL METHYL PROPYL ACETONE KETONE KETONE

180

160

140

120

δ Ι 0 0 | α.

80 ο m

60

40

20

10

II 090 mm. —

747mm.

2 00 mm.

>r r

1 1

11,09 Omm

4,€ >30rr im.

\ I

2,0 40 m m.

75 7mn

)

)—— 27 5mm

kl

10 Omm

IV

\ 5,4 00 m m. 00 m m.

•71 Î7mn n. — Ν \

f V ,

Î7mn n. —

I • •

)

10 Omm • — Omm • —

\ r

\\ 0 20 40 60 80 KX) 0 20 40 Θ0 80100 0 20 40 60 80 100 WEIGHT PER CENT ALCOHOL

Figure 1. Vapor-liquid equilibrium diagrams of alcohol-ketone systems at various pressures


Alcohol-Ketone Azeotropes 625

METHANOL- ETHANOL-METHANOL METHYL ETHYL METHYL PROPYL ACETONE KETONE KETONE

Ο 20 40 60 80 100 0 20 40 60 80100 .0 20 40 60 80100 AVERAGE WEIGHT %ALC0H0L IN LIQUID AND VAPOR IN EQUILIBRIUM

Figure 2. Difference in composition of vapor and liquid in equilibrium

Shown as a function of corresponding average composition of vapor and liquid for alcohol-ketone systems


Graphical Method for Predicting Effect of Pressure on Azeotropic Systems

H. S. NUTTING and L. H. HORSLEY

The Dow Chemical Co., Midland, Mich.

A rapid and easily applicable method has been found for indicating the effect of pressure on the composition and boiling point of an azeo

tropic system. The method is based on the use of the Cox vapor pressure chart (1) on which the log of vapor pressure is plotted as a function of 1/(t° C. + 230) to give a straight line over a wide range of pressures.

Lecat (2) has considered the use of the vapor pressure curves of azeotropes to indicate the pressure at which a system would become nonazeotropic. However, he plotted in the conventional manner and could obtain the curves only by detailed experimental work.

It has been found that the vapor pressure curves of azeotropes are straight lines when plotted on a Cox chart which permits determination of the complete vapor pressure curve from the data at two pressures.

Since an azeotrope by definition has either a higher or a lower vapor pressure than that of any of the components, the azeotropic vapor pressure curve will always lie above or below the curves of the components. This is indicated schematically in Figure 1 where A and Β are vapor

AZEOTROPE DISAPPEARS AT Ρ AND P1 AZEOTROPIC AT ALL PRESSURES COX SCALE l / ( T ° C . + 230)

Figure 1. Schematic of vapor pressure curves of binary azeotropes

626


Effect of Pressure 627

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pressure curves of the components and C is the vapor pressure of the azeotrope. If curve C crosses either A or B, the azeotropic vapor pressure is no longer greater or less than any of the components and the system will become nonazeotropic at the point of intersection. On the other hand, if the azeotropic curve is parallel to the other curves the system will be azeotropic up to the critical pressure.

The method has been successfully applied to numerous systems, four of which are shown in Figure 2. The azeotrope methanol-methyl ethyl ketone became nonazeotropic at 3000 mm. of mercury after it was predicted that this would occur at 2000 to 4000 mm. The azeotrope methanol-acetone was studied in detail after it was predicted that the azeotropism would disappear at both low and high pressures. This system is nonazeotropic below 200 mm. of mercury and above 15,000 mm. compared to predicted limits of 200 to 500 mm. and 10,000 to 20,000 mm. While this is the only azeotropic system known to become nonazeotropic at both low and high pressures, there are indications that the phenomenon occurs in several other systems, contrary to the conclusions of Lecat that such systems probably do not exist (3).

Caution should be used in extrapolating curves to very low pressures because of the possibility of curvature in the vapor pressure lines over a manyfold range of pressures.

In cases where only the normal azeotropic boiling point is known, it is possible to predict the effect of pressure on the sytem by drawing the azeotrope curve through the normal boiling point with a slope equal to the average slopes of the component vapor pressure curves. This procedure will permit a fairly accurate prediction of whether the azeotrope will cease to exist below the critical pressure.

Literature Cited (1) Cox, Ind. Eng. Chem., 15, 592 (1923). (2) Lecat, Ann. soc. sci. Bruxelles, 49B, 261-333 (1929). (3) Lecat, "Traité de Chimie Organique," Vol. 1, p. 139, Paris, Grignard,

Mason et Cie., 1935.


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Lee H Horsley Azeotropic Data-III