POLYHYDROXY PHENOLS AND METHOD FOR PREPARING THE SAME

PREPARATION DE POLYHYDROXYPHENOLS

English Abstract

ABSTRACT OF THE DISCLOSURE
Polyhydroxy phenols according to the formula:
<IMG>
where R is a hydrocarbon radical containing from 1 to 4
carbon atoms, R1 is the radical <IMG>, and
R2 is a hydrogen atom or the radical R1.
The above polyhydroxy phenols can be used in the prepara-
tion of hardened epoxy resins with improved stability, or
in the preparation of improved phenolic resins.

Claims

WE CLAIM:
1. A polyhydroxy phenol defined by the formula:
<IMG>
where R is a hydrocarbon radical containing from 1 to 4 carbon
atoms, R1 is the radical <IMG> , and R2 is hydrogen
or is equal to R1.
2. A process for preparing a polyhydroxy phenol of claim 1
which comprises:
(a) reacting formaldehyde and a diphenol of the formula:
<IMG>
where R is a hydrocarbon radical containing from 1 to 4
carbon atoms, in n formaldehyde/diphenol molar ratio of at
least 1:1, in an aqueous medium and at a temperature of at
least 40°C, in the presence of an inorganic base, thereby to
form a methylol derivative of said diphenol;
(b) adding an acid to the reaction products of (a) in an
amount at least equivalent to that of said lnorganic base,
and an organic solvent capable of dissolving said methylol
derivative,immiscible or only slightly mlscible with water
and forming with the latter an azeotropic mixture, and separ-
ating the aqueous phase and the organic phase thus obtained;
(c) contacting said organic phase with phenol in an amount
of at least one molecule for each methylol group of said
derivative present in said organic phase, in the presence
-13-

of an acid catalyst and at a temperature of at least 100°C,
and maintaining the resulting mixture at boiling point
until substantially complete reaction of said derivative
with phenol, while distilling the forming water as an
azeotrope with said organic solvent; and
(d) recovering the polyhydroxy phenol from the reaction
products of (c).
3. The process of claim 2, wherein said diphenol is 2,2-
bis(4-hydroxyphenol)propane or p,p'-methylenebisphenol.
4. The process of claim 2, wherein said formaldehyde
is fed into the reaction medium of (a) in the form of an
aqueous solution or a substance which frees formaldehyde
under the reaction conditions.
5. The process of claim 2, wherein said formaldehyde/diphenol
molar ratio is from 1:1 to 4.1.
6. The process of claim 2, wherein the molar ratio between
said inorganic base and said diphenol is from 0.3:1 to 2:1.
7. The process of claim 2, wherein the molar ratio between
said inorganic base and said diphenol is from 0.5:1 to 1:1.
8. The process of claim 2, wherein said inorganic base is
an alkali metal hydroxide.
-14-

9. The process of claim 2, wherein the reaction medium
of (a) has a water content of from 25 to 40% by weight.
10. The process of claim 2, wherein stage (a) is carried
out at a temperature of from 40 to 80°C.
11. The process of claim 2, wherein stage (a) is carried
out for a time of from 1 to 4 hours.
12. The process of claim 2, wherein said acid of (b) is
an inorganic acid.
13. The process of claim 2, wherein said acid of (b) is
selected from the group consisting of hydrochloric, sulphuric
and phosphoric acids.
14, The process of claim 2, wherein said acid of (b) is added
in an amount such as to bring the pH to a value of from
5 to 6.
15. The process of claim 2, wherein said organic solvent is
selected from the group consisting of aromatic hydrocarbons
or aromatic naphthas with a suitable boiling range.
16. The process of claim 2, wherein said organic solvent
is selected from the group consisting of toluene, xylene
and cumene.
-15-

17. The process of claim 2, wherein said resulting mixture
of (c) contains from 2 to 3.5 moles of phenol for each
methylol group.
18. The process of claim 2, wherein. said mixture of (c) is
boiled at a temperature from 100° to 160°C.
19. The process of claim 2, wherein said acid catalyst is
an organic acid.
20. The process of claim 2, wherein said acid catalyst is
an acid having an acid dissociation constant, or else (in
the case of a polybasic acid) a first acid dissociation
constant above 1.10-5.
21. The process of claim 2, wherein said acid catalyst is
used in an amount of from 0.4 to 1.5 parts by weight for each
100 parts by weight of diphenol used in (a).
22. The process of claim 2, wherein said acid catalyst is
selected from the group consisting of oxalic, acetic, mono-,
di- and tri-chloroacetic, fumaric, isophthalic, formic,
benzoic, para-toluene sulphonic and phenol sulphonic acids.
23. The process of claim 2, wherein stage (c) is carried out
for a period of from 2 to 8 hours.
-16-

24. The process of claim 2, wherein said polyhydroxy
phenol is recovered by precipitating the acid catalyst
and removing the resulting precipitate, and distilling
off the organic solvent and unreacted phenol present in
said reaction products of (c).
-17-

Description

78~3~3
- This .invention relates to new polyhydroxy phenols
: ` defined by the general formula:
R1 ~ . 2
(I) HO _ ~ _ R ~ OH
R2 2
wh0re R is a hydrocarbon radical containing from 1 to 4
: atoms of carbon, R1 is the radical -CH2 ~ _ OH, and
; R2 is hydrogen, or else i~ equal to ~.
This invention concerns, also 9 a method ~or the
- preparation of the ~aid polyhydroxy phenol~.
According to the proces~ of this invention a diphenol:
'
~ (II) HO - ~ _ R ~ _ OH
., . : . .
where R has the above meaning, is reacted with formaldehyde
, ! 80 ao to attach a methylol group (-CH20H) ln at least one ofthe ortho positions, in relation to the phenolic hydroxyl of
,.1. ' . . .
' ~ the phenol rings of the diphenol and the methylol derivative,: i . -
' ' i9 reacted with phenol 50 as to~gi~e the polyhydroxy phenol
`: 1 . .
In the rOl lowing spe ciri cation:
~¦ ~ by "diphenol" i~ meant a compound defined by means
:,'
¦ . o~ Formula (II);
b~ ~methylol derivative" or "methylol intermediate"
is meant the compound (II) bearing at least one methylol
~ I .
. ¦ group in the ortho position3 in relation to the phenolic
~ii - hydroxyl group3; i
:j -2-
. ~
,

:~0~8~'73
- by "polyhydroxy phenol" i5 me~nt a compound defined
. , by ~ormula (I).
- The process for preparing the p~l~hydroxy phenols of
the invention comprises the followin~ stages~
~ a) reacting formaldehyde and a diphenol of the
formula:
HO._ ~ _ R _ O OH
where R i9 a hydrocarbon radical containing from 1 to 4
carbon atoms, in a ~ormaldehyde/diphenol molar ratio of at
; least 1:1, in an aqueous mediD~ an~ at a~temperature of at
.: least 400C, in the present of an inorganio base, thereby
to form a methylol derivative of said diphenol;
~ b) adding.an acid to the reaction products of (a) in
an amount at least equivalent to that of said inorganic base,
., .
.~ . . and an organic solvent capable of dissolving said methylol
¦ derivative, immiscible or only slightly miscible with
:' I .
water and forming with the latter an azeotropic mixture~
~; and sepa~ating the aqueous phase and the organic phase thus
.: l ~ .
, obtained;
¦ (c) contacting said organic phase with phenol in an
¦ amount of at lea~t one molecule for each methylol group of
¦ said derivati~e present i~ said organic p~ase, in the presence
.~ .
:~. o~ an acid catalyst and al a temperature of a~ least 1 OO~C9
. ,and maintaining ths resulting mixture at boiling point, until
.~ substantlally complete reaction of said derivatlve with
~¦ phenol, while~di~tilling ~he forming watar à~ an azeotrope
:. : ~3-
.. ~
; : .
.: I
.

1~ 373 .
with said organic solvent; and
[d,)l~recovering the polyhydroxy phenol from the reaction
~` products of (c)O
`~ Sta~e,_(a2
' ~ The diphenol~ usable for the purposes of this inventi.on
ar~ t,~,sje;defined by the ~ormula (II) w~ere R is a hydroca'rbon
radical having from 1 to 4 carbon atoms.
Particularly userul for the purpose are 2~2 - bis (p-
hydroxyphenyl) propane (bisphenol - A) and p,p'-methylene-
diphenol,
The formaldehyda can be fed into the reaction medium
. . .
as an aqueous solution, speclally in the form of those
commercial aqueous ~olutions having a formaldehyde content
: of the order of 36 - 38% by weight~
One can also use for the purpose low polymers of formal-
dehyde, such as paraformaldehyde or anyway any substance
'' whlch'frees formaldehyde under the reaction conditions.
.
~'', The reaction ig catalyzed by an inorganic base~ preferably
an alkali metal hydro~ide, such QS sodium or potassium
- hydroxide.
:1 , .
' The molar ratio between the formaldehyde and the diphenol
! is dependent upon the number of methylol groups which it
,
is intended to bind to the diphenol, an~ hence the said ratio
generally varies from 1:1 to 4:1.
However, since complete reaction of the formaldeh~de
requires excessively high reaction times, it is pre~erable
to use the said formaldehyde in an amount olightly in excess
_4_
'~ . ' ` '' ' ' ` i

~L~713~3
of tha~ which is stoichiomotrically ~cessary for the
desired reaeti~ and ~enerally up to 1~/0 ~n excess of the
stoichiome~ric value.
The molar ratio between the inorganic bas~ and the
diphen~l is generally from 0.3:1 to 2:1, and preferably
from 0~5;1 te 1~
The water content of the reaction medium is pre~erably
from 25 to 400/o by weight. When the water content i9 beyond
the above range there then occur, essentiallr, the drawbacks
related to non--optimal separation or even sometimes precipi
tation of the methylol intermediate in the subsequent stage
(b). The best results are obtained with a water content of
from 30 to 3~% by weight in the reaction medium. ~urther,
operation is preferably carried out at a temperature o f from
40 to 80C and until complete reaction o~ the diphenol, or
at least until the concentration of the latter is reduced
.:
to values below 2~ by weight in the reaction medium. The
.
reaction time is generally from 1 to~4 hours and the content
in ~ree formaldehyde at the end of the reaction period is
.~
generally from 0.1 to 4.0~ by weight, still in relation to
the reaction medium. The values preferred ~or the temperature
~¦ are of the order of 609C and for thQ periods of from 1.5 to
~l 2 hours.
¦' Tho way of contacting the reagent3 i9 not critical,
.1 . ,
but it is nevertheless preferable to gradually add an aqueous
¦ solution o~ the inorganic base to the reaction medium contai-
.
l ning the formaldehyde and the diphenol~ and to keep the reac-
i ~ ' .
.

gL~788~3
tion mixture at reaction temperature for a period of time
1 at the end of the addition of the inorganic ba~e.
`; Finally the water required in the reaction medium can
expediently be added in the form of the aqueous solutions
of inorganic base and/or formaldehyde.
e (b3
'f
~- To the reaction products of stage ~a) there is added
an acid in an amount at least equivalent to that of the
inorganic base used in the said sta~e (a).
,
Organic acids may be used for the purpo3e, but mineral
acids, such for example as hydrochloric, sulphuric and
phosphoric acids are preferred. Among these latter, phosphoric
acid i9 preferred, for reasons of corrosion.
The amount of acid which is generally added is that
required for bringing the pH of the reaction medium to a
value of from 6 to S-
As well as the acid there is also added an organic
,, .~ .
~ ~ solvent which ig capable of dissolvi~ the methylol interme-
: i : .
diate produced in stage (a), is immiscible~ or hardly miscible,
` with water~ and forms ~ith the latter an azeotropic mixture.
Particularly userul for the purpose are the aromatic hydro-
~ ` carbons ~uch as toluene, x~lene, cumene, or aromatic naphtha~
i of pit-coal~ or of petroleum~ having an appropriate boiling
!: range.
The amount of organic solvent added i8 not critical
xcept for the fact that it ha3 to be at least sufficient to
_ '` 6 `
:
,
: .
.
~_ - .-'!7~-~'`~ f ~, ~'` ~ r
. . . . ~
. . . . ..

131373
ke~p th~ methylol intermediate di~;solved.
.It l~.expedi.snt in this stage o~ the process to operate
. at a telnperature of the order of 30 ~ 400C9 adding firstl~
the organlc solvent to the react~on products of stage (a)
and then the acid, gradually, whilst keeping the mass
agitated.
; . Finally the mass is decanted with separation o~ an
aqueous pha~a which contains in solution the inorganic
products and any unrsacted formaldehyde, and of an organic
phase containing the methylol intermediate.
The aqueous phase is discharged, whilst the organic phase
is subjected to treQtment in the subsequent stage.
: Stage (c)
To the solution of the methylol intermediate in organic
solvent recovered in &tage (b), phenol is added in an amount
of at least one molecule for each methylol group of msthylol
l . . intermediate~present in the solution.
:l . It i~ generally preferable to operate with an amount of
":1 . . -
. phenol in e~cess of this equivalent value~ i.e. an amount
Or from 2 to ~.5 moles for each methylol group.
In faot! when.said amount i9 less than 2 moles, by-
-- ; products form in relatively high quantities, whilst no sub-
stantial improvements are obtained with amounts superior to
the maximum indicated.
-1 , . .
One operates moreover at boiling point~ generally at a
temperature from 100C to 160~C, continuously distilling the
water which is forming in the form of an a~eotrope with the
: -7-
~,''i : . .

~L07~3~373
; . pre-se1.ected organic solvent.
Rea~ç~tion :of the methylol lntQrmediate with phenol is carried
out i~ t~e prese~ce of an acid~c~taly t, preferably an org~nic
. .
acid.
The acid should preferably have an acid dissociation
~o.ns~.tt~ or else (in the ca~e o~ polybasio acids~ ~ ~irs.t
--5
: . acid dlssociation constant above 1.10 . ~xamples of these
acids are: oxalic~ acetic~ mono-? di-and tri-chloroacetic,
~umaric, isophthalic, formic, benzoic, para-toluenesulphonic
: and phenolsulphonic acids.
.~...... .
The amount of catalyst acid is generally from 0.4 to 1.5
. parts b~ weight for each 100 parts by weight of the initial
feed in diphenol.
.
The reaction times are those required for practically
complete reaction of the methylol intermediate and are
generally from 2 to 8 hour~.
. . ,
In a preferred embodiment, the organic solution of the
.
mathylol intermediate is gradually added to the phenol a~d
; the ac.id catalyst. The mass i~ moreover kept boiling and the
.. . . .
resulting vapours are condensed with separation of an aqueous
. phase1 whioh is dlscharged, and o~ an organic phase which is
~:` recycled into the reaction medium.
. Stage (d)
¦ The acid catalyst~ the organic solvent and any possible
¦ . e~cess o~ phenol are removed from the reaction products of
.'~ : '
~tage (c). - ~
. In case oxalic acid is used, the said acid i9 insoluble
, . .
.:
-! -8-

7l3873
in the reaction medium at a temperature o~ the order of
80 ~ 90Co It can the~efore be precipitated by cooling the
reaction mass, and then filtered. In other cases it may be
necessary to neutralize the acid to form an insoluble salt,
which is then filtered.
, ~ ,
The organic solvent and the excess phenol can be r0moved-
~the ~irst by diistlliation at atmo~pheric or near atmospheric
pressure, and the second at subatmospheric pressure 9 prefera-
bly by means of the thin film method. Obvio~i31y the said
organic soivent and phenol can be re-used in the preparation
the polyhydroxy phenol. The latter remains in any case as
a distillation residue.
~ B~ mean6 of the me-thod of this in~ention one generally
:~, . :
obtains a mixture o~ variously substituted polyhydroxy
phenols (I).
. j ' .
~i The said mixture can be utilised as such for uses which
will be described below. Obviously, ir wished, the individual
oompounds can be separated by normal methods, such~ for
example~, as fractional crystallization~
The polyhydroxy phenols of this inventi~n are espeoial1y
useful: ~
, - in the synthesis o~ epoxy resins by reaction with
epichlorohydrin in the presence of alkali; the epoxy
reslns thus obtained give hardened products with
greater ther~al and dimensional ~tability as well ais
¦ with higher resistance to chemical reagents; !
'.' ~ , , .,, .
1 - 9 ~
-, .. ., . . ~ . ~ j
, ,- . . . . .. .

71~3~373
- ~n the pr~p~ration of phenolic resins of the Novolak
t!ype with higher molecular weight than conventlonal
re~in~, by reaction~with ~orm~ldehyde; the said
Novola~s are used in the manufacture of foundry cores,
abrasive grinding machines and moulding po-~dars;
in the preparQtion of resols by reac~ion with formà~l- :
. dehyde under basic conditions; the said resols are used
in the manufacture of ornamental, mechanical and multi-
layer laminates.
In the following experimental example ths parts and percen-
tages are by weight unless otherwise specified.
Exampls
A reactor fitted with an agitator, reflux condenser,
demixer f~r azeotropic distillation, and measurer, is charged
with 449 par$s of Bisphenol-A, 58 parts of flaked sodium
, ,
hydroxide and 165 parts of water.
')
One heats to 60~C~ and to the agitated mass there are
added in one hour 411 parts o~ a 36~ aqueous sol~ltion of for-
maldehyde. At th~ end of th2 additio~ formalde~yde the
~ormaldehyde/bisphenol-A molar ratlo is equal to 2.5:1~ the
sodium hydro~ide/bisphenol-A molar ratio is equal to about
.
0.~:1 and the water content of the reaction medium is of the
order of 38%. ~ -
¦ After the addltion Or formaldehyde the mas~ i~ keit
under agitation at 600C for 30 minutes and a clear 60lution
.,, , . :
- is obtained the ~ormaldehyde conten$ of which is e~ual to
0,2~. ,
:
., :

~t)7~373
The mass is then cooled to 30 - 40C and there are
add~d 78 parts o~ ~oluene and 131 parts of a 75% aqueous
solution of phosphoric ~cid.
Addi~ion of the acid is effected in 30 minutes. At
the er,d of this period of timej agitation is kept up for 10
minutes and then the agitator is stopped and the mass is
decanted. Thus there are rapidly separated an aqueous phase
(490 parts) and an organic phase.
The latter has the following characteristics:
- dry residue : 72%
- toluene : 10%
- water : 16
- free bisphenol-A : 1.7~
This last test is carried out by means of gas-chro-
matography.
The organic phase (800 parts) is poured gradually in
3 hours into a mixture of 927 parts of phenol and 3.2 parts
of oxalic acid, which has been brought to 100C.
During the addition of the organic phase, the boiling
temperature rises to 118 - 120C in 30 minutes. During the
said addition, the water which forms is eliminated from the
boiling mass by azeotropic distillation with toluene, and
the distilled toluene is recycled.
i After the addition of the organic phase the mass is
kept boiling for another 4 hours, and the temperature thus
rises to 160C with removal of 198 parts of water.
A reaction mass is thus obtained with a solids content
. . .
.. .
ph~
'.~
~ , . '.
,. . . . . .

78~il73
Of 68% and a content in fr~e phenol of 34% ~g~s-chromato-
graphic analysis), This mass is cooled to 120C, 260 par~s
of toluene are then added, and the resulting mass is
filtered at 90C on a plate filter with a filter aia.
The filtrate is subjected to distillation at atmospher-
ic pressure in order to remove the toluene.
Then the phenol is removed by distilling at 3-4 mm Hg
without exceeding the temperature of 160C until the residual
content in phenol in the bottoms is less than 1~.
The dis~illation residue is discharged as a thin layer,
cooled and sub]ected to the followlng tests:
- appearance : clear solid
- melting point (in a capillary) : 90 - 100C
' - free phenol (gas-chromatography) : 0,7%
- free bisphenol-A (gas-chromatography) : 0.7
- Gardner melting colour : 7
- viscosity at 25C in 50~ ethanol solution : 80 cps.
The structural analysis carried out by NMR gives the
. following results :
. 20 - average numerical molecular weight: 490
- average number of aromatic rings per molecule: 4.5
; - average number of aromatic protons per ring: 3.3
- averase number of methylene bridges per aromatic ring: 0.6
i '~ '
' : '
'
I - 12 -
!
ph~