The Preparation and Reactions of Pentafluoropropionaldehyde

116 Pages·4.787 MB·English

by  Higgins, James F

PURDUE UNIVERSITY
THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION
by James F. Higgins___________________ ________________
en titled THE PREPARATION AND REACTIONS OF PENTAFLUORQ-
_________ PROPIONALDEHYDE____________________________________
COMPLIES WITH THE UNIVERSITY REGULATIONS ON GRADUATION THESES
AND IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS
FOR THE DEGREE OF
____________________Doctor of Philosophy________________
Professor in Charge of Thesis
Head of School or Department
THIS THESIS IS NOT TO BE REGARDED AS CONFIDENTIAL.
GRAD* SCHOOL FORM 9

THE PREPARATION AND REACTIONS OF PENTAFLUOROPROPIONALDEHYDE
A thesis
Submitted to the Faculty
of
Purdue University
by
James F. Higgins
In Partial Fulfillment of the
Requirements for the Degree
of
Doctor of Philosophy
June, 1951
ProQuest Number: 27714075
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ACKNOWLEDGEMENT
The author wishes to acknowledge the assistance of Professor
E. T. McBee, who was in direct charge of this work. Many thanks are
also due to Dr. 0. R. Pierce, >diose helpful suggestions aided greatly
in the completion of this research. The author wishes to extend his
gratitude to Dr. H. C. Brown and Dr. Nathan Kornblum for suggestions
on the interpretation of data. The help of several graduate students,
among whom are W. F. Mara luff, W. Lawton, L. Kohn and W. Diveley, was
also greatly appreciated. This work was supported by the Westinghouse
Electric Corporation.
TABLE OF CONTENTS
Page
ABSTRACT
Park 1. The Synthesis of Compounds Containing the
Pentafluoroethyl Group...................................................» . i
Part II. The Reducing Action of Grignard Reagents on
Fluorinated Carbonyl Compounds, . . . . . . . . . xiv
Part III. The Synthesis of Ethyl 2,2-Dichloro-
cyanoacetate ...................... . . . . . . . . . . . . xxiii
PART I. THE SYNTHESIS OF COMPOUNDS CONTAINING THE
PENTAFLUOROETHYL GROUP.
Discussion......................... . 1
Experimental . . . . . . 13
PART II. THE REDUCING ACTION OF GRIGNARD REAGENTS ON
FLUORINATED CARBONYL COMPOUNDS.
D iscussion.......................... .................................. 30
Experim ental........................................................... 51
PART III. THE SYNTHESIS OF ETHYL 2,2-OICHLOROCYANO-
ACETATE AND 1,3,5-TRIAZINES.
Discussion...................................................................................... 57
Experimental . . . . . . . . . . . . . 64
BIBLIOGRAPHY...................................................................................................... 74
APPENDIX OF REACTIONS..................................................................................... 77
VITA
LIST OF TABLES
Table Page
I Comparison of Physical Properties............................................................26
II New Compounds.................... 27
III Table of D erivatives................................ 29
IV Reactions with Fluorinated Aldehydes. . . . . . . . . . . . 52
V Reactions with Ethyl G rignard.................... 52
VI New Compounds ..................... . . . 53
VII Summary of Experimental Data
Grignard Reactions of Pentafluoropropionaldehyde . . . . . . 55
VIII Summary of Experimental Data
Grignard Reactions of Trifluoroacetaldehyde...................................55
IX Summary of Experimental Data
Reactions of Ethyl Grignard with Fluorinated Carbonyl
Compounds............................................................................................. 56
k {Contribution from the Department of Chemistry
and Purdue Research Foundation, Purdue University)
THE SYNTHESIS OP COMPOUNDS CONTAINING
THE PENTAFLUOROETHYL GROUP (1)
(1) This paper represents part of a thesis submitted by J, F, Higgins
to the Graduate School, Purdue University in partial fulfillment of the
requirements for the degree of Doctor of Philosophy. This work was sup­
ported by the Westinghouse Electric Corporation.
By E. T. McBee, J, F. Higgins and 0. R. Pierce
ABSTRACT
The reactions of pentafluoropropionaldehyde and 3,3,4,4 *4-penta-
fluoro»2-butanone with alkylmagnesium halides have been investigated
as a means of preparing a series of pentafluoroethyl ethylenes,. Normal
addition products were obtained as well as materials formed by the re­
duction of the aldehyde and ketone. Dehydration of the fluorinated
alcohols produced could not be accomplished with sulfuric acid, hot
alumina or pyrolysis of the corresponding xanthate or acetate esters.
However, phosphorus pentoxide was successfully employed. Twenty-
new fluorine-containing compounds are described*
DISCUSSION
The preparation of a series of olefins containing the pentafluoro­
ethyl group was undertaken because of interest in the effect of adjacent
groups containing fluorine on the reactions of double bonds. It was
ii
planned to synthesize the six possible compounds of the type where R
could be hydrogen or a methyl group.
The reaction of pentafluoropropionaldehyde (1) with methyl, ethyl,
(1) Hasted and Albrecht, HSth Meeting of The American Chemical Society,
Chicago, 111., September 1950.
and isopropyl Grignard reagents and subsequent hydrolysis was expected
to yihld alcohols, which on dehydration would give three of the desired
olefins. Although méthylmagnésium iodide gave the addition product,
3,3,4>4>4-pentafluoro-2-butanol, in 85# yield, ethyLmagneslum iodide
gave osiy 33.6# of the addition product, 1,1,1,2,2-pentafluoro-3-
pentanol and 55.5# of the reduction product. When pentafluoropropion­
aldehyde was added to isopropylmagnesium iodide only the reduction pro­
duct (90#) was isolated. The occurrence of reduction, where very little
aterie effect exists^ indicates that another factor, due to the presence
of the fluorine, is operative.
Similar results were obtained with ethyl and isopropyl Grignard re­
agents sud 3,3,4,4,4-pentafluoro-2-butanone. With ethylmagneslum iodide,
the addition product, 3-methyl-l,1,1,2,2-pentafluoro-3-pentanol, was
obtained in 41.6# yield and the reduction product, 2,2,3,3,3-pentafluoro-
propanol, in 44.5# yield. Isopropyl Grignard yielded only the reduction
product (54#). Thus only one of the desired alcohols, 3-methyl-l,1,1,2,2-
pentafItioro-3-pentanol, was obtained by the action of Grignards on the
ketone,
> f Since it appeared that extensive reduction could be predicted when
iii
a carbonyl compound contained several fluorine atoms adjacent to the car­
bonyl group, the ethyl ester of pentafluoropropionic acid was reacted
with isopropyl Grignard in the hope that the intermediate ketone would
be reduced to the desired secondary alcohol, which could not be obtained
from the same Grignard and pentafluoropropionaldehyde. This was achieved
in 35# yield. Work by Campbell (2) has since shown that this type of
(2) Campbell, Knobloch and Campbell, THIS JOURNAL, 22 4380 (1950)
reaction is general for esters of trifluoroacetic acid. The last alcohol
necessary as an intermediate for the olefin series was easily prepared
by the action of méthylmagnésium iodide on ethyl 2,2,3,3,3-pent afluoro-
propionate in 76$ yield.
The difficulty of dehydration of these alcohols was such that only
two olefins were actually prepared. 3,3,4,4,4-Pentafluoro-l-butene was
formed by heating the secondary alcohol with phosphorus pentoxide to
275® C. With the same reagent, 2-methyl-3,3,4,4,4-pent af luoro-l-but ene
was formed from the corresponding tertiary alcohol. The secondary
alcohol, 3,3,4,4,4-pentafluoro-2-butanol, did not dehydrate when heated
in concentrated sulfuric acid. Carbonization occurred when pyrolysis of
its acetate at 450° C. was attempted, and no olefin was obtained. The
methyl xanthate of the secondary alcohol did not decompose on refluxing
at atmospheric pressure (b.p. 151-2°). Attempted dehydration of 3,3,4,4,4-
pentafluoro-2-butanol over activated alumina at 300-500° failed to yield
the olefin. Since products not condensable in a dry-ice cooled trap
were formed, it is probable that the molecule underwent cracking. The
reaction tube was etched slightly in this experiment indicating hydrogen
fluoride formation. The strengthening of the carbon-oxygen bond in these