Chlorinated phenol mold release agent

In an improved process for preparing chlorinated phenol by the reaction of molten phenol with chlorine in the presence of a Friedel-Crafts catalyst, the improvement comprises adding to the molten chlorinated phenol product, immediately on completion of the chlorination process, at least 0.5 weight percent of a glycol ether thereby inhibiting dioxin formation, inhibiting decomposition of the technical grade chlorinated phenol and most importantly, imparting mold release properties to the final product which is cast in corrosion-resistant molds, preferably stainless steel or plastic-lined steel molds.

BACKGROUND OF THE INVENTION 
Chlorinated phenols exhibit outstanding germicidal and insecticidal 
properties and have demonstrated utility as flea repellants, fungicides, 
wood preservatives, mold inhibitors, etc. In general, biotoxic 
effectiveness increases with the degree of chlorine substitution. 
Technical grade chlorinated phenols have been found to decompose readily 
in the presence of metals, metal chlorides and heat to form large volumes 
of hydrogen chloride and tar. Product degradation is attributed to the 
presence of metal ions in storage and process vessels and small amounts of 
catalyst residue, i.e., aluminum and iron chlorides present in the 
technical grade chlorinated phenol product. Elevated temperatures are also 
known to accelerate the decomposition reactions. 
In addition to decomposition difficulties, technical grade chlorinated 
phenols contain some impurities which give rise to objectionable color 
formation, typically a dark red or dark brown color. Other impurities 
include a family of high molecular weight compounds polychlorinated 
dibenzo-p-dioxins, known to have toxic properties. Other polychlorinated 
polynuclear impurities, the chlorinated phenoxyphenols, are a primary 
cause of blooming of the impure chlorinated phenol. Thus, high molecular 
weight impurities in the technical grade chlorinated phenols cause dark 
coloration, cause blooming and impart toxic properties in the form of 
dioxins. 
Various processes of inhibiting decomposition of the crude chlorinated 
phenol during distillation are known. The distillation process has also, 
heretofore, facilitated the removal of dioxins formed. High boiling amines 
or alkanolamines have been disclosed as useful in stabilizing impure 
pentachlorophenol against decomposition during distillation (U.S. Pat. No. 
3,816,268). Zinc dust or ethylene thiourea have been used to improve color 
and reduce the chlorodioxin content of impure pentachlorophenol during 
distillation (U.S. Pat. No. 3,909,365). Free-radical acting substances, 
e.g., phenols, hydroquinones, organic sulfur derivatives, organic 
phosphite, amine- and aldehyde-type compounds, have been used to improve 
color and reduce the chlorodioxin content of impure pentachlorophenol 
during distillation (U.S. Pat. No. 4,016,047). Polyhydroxy compounds, 
selected from the group consisting of sugars, polyhydric alcohols, 
polyglycols, and polyglycol ethers, have been incorporated into impure 
pentachlorophenol as decomposition inhibitors during distillation (U.S. 
Pat. No. 4,142,943). Salicylaldehyde and water and Reimer-Tiemann residues 
from the preparation of salicylaldehyde have also been disclosed as useful 
to remove impurities during the distillation of pentachlorophenol (U.S. 
Pat. No. 3,852,160 and 3,852,161). 
The variety of materials offered for the purpose of producing chlorinated 
phenols which are desirable both from the aesthetic viewpoint and the 
environmental viewpoint is, to some extent, evidence that none is without 
disadvantage. Some of the materials identified by the prior art are very 
effective in inhibiting chlorinated phenol decomposition and/or preventing 
toxic by-product formation; however, neither of these desired results was 
possible without distillation. The underlying problems that have not been 
solved, by the prior art, are the formation of dioxins in the crude 
pentachlorophenol which made the distillation step necessary, and the lack 
of adequate mold-release properties in either technical grade or distilled 
product stored in corrosion-resistant vessels. 
As an illustration, chlorinated phenols are conventionally prepared by the 
reaction of molten phenol with chlorine in the presence of a 
Friedel-Crafts catalyst such as aluminum chloride at temperatures which 
result in the production of a molten product. When the crude chlorinated 
phenol exits the reactor vessel in a molten state, further treatment, at 
temperatures above its freezing temperature, is required to prevent 
decomposition and toxic by-product formation. The treated chlorinated 
phenol product then proceeds to a storage vessel having a mold cavity 
where the mixture cools to a solid product. Heretofore, release of the 
solid product from the molds in which they are stored has presented severe 
difficulties. For example, the solid product adheres to the wall of the 
mold cavity and seriously complicates the subsequent removal and 
distribution of the chlorinated phenol product. It is desirable to 
efficiently remove the solid product from the mold cavity thereby 
providing a clean mold capable of accepting additional molten product. The 
utilization of an internal release agent in the treated chlorinated phenol 
product is also highly desirable and would avoid the obvious disadvantages 
of using an externally applied release agent to the mold cavity. 
No prior art has been found which teaches the use of the compounds 
specified herein to impart mold-release properties to chlorinated phenols 
in addition to inhibiting dioxin formation and decomposition at high 
temperatures. 
SUMMARY OF THE INVENTION 
At least 0.5 weight percent of a glycol ether compounds, based on the total 
weight of molten chlorinated phenol product effectively imparts 
mold-release properties to the final product in addition to inhibiting 
dioxin formation and inhibiting decomposition of the technical grade 
chlorinated phenol prepared by chlorinating phenol in the presence of a 
Friedel-Crafts catalyst. 
When molten chlorinated phenol containing a glycol ether compound is stored 
in corrosion-resistant molds, the product solidifies on cooling and yet 
remains easily extractable from the mold, preferably a stainless steel or 
plastic-lined steel mold. 
DETAILED DESCRIPTION OF THE INVENTION 
Although the process of the present invention may advantageously be 
performed on any crude or distilled chlorinated phenol, it has been found 
that the present process is particularly applicable to the treatment of 
pentachlorophenol to impart mold-release properties and significantly 
improve product quality with or without distillation, as desired. 
In general, crude pentachlorophenol exits the reactor vessel in a molten 
state at temperatures above its freezing temperature, i.e., 185.degree. C. 
If poured into a corrosion-resistant storage vessel prior to treatment 
with an inhibitor, the pentachlorophenol begins to decompose into hydrogen 
chloride (HCl) and tar. The early addition of a suitable amount of 
inhibitor retards decomposition of the pentachlorophenol and inhibits 
toxic dioxin formation when the crude molten product is being handled or 
stored in corrosion-resistant containers, at temperatures between 
175.degree. C. and 230.degree. C. However, when the crude chlorinated 
phenol is allowed to cool to room temperature (23.degree. C.) or below, it 
solidifies and has been found to adhere to the walls of the 
corrosion-resistant storage vessel. Dioxin formation occurs in any 
environment above 100.degree. C. if the Friedel-Crafts catalyst residue 
remains active. Thus, in order to prepare a stabilized chlorinated phenol 
which is easily removed from a corrosion-resistant storage receptacle, it 
is advantageous to add a small amount of a mold-release agent, i.e., 
glycol ether compounds, directly to the crude chlorinated phenol in the 
molten state and before significant decomposition occurs. The addition of 
a glycol ether compound immediately after termination of chlorination, 
with agitation, gives the most beneficial results. By the process of this 
invention, decomposition of the crude chlorinated phenol is significantly 
retarded; toxic dioxin formation is reduced to acceptable parts per 
million levels, and the surprising and unexpected phenomenon that is the 
essence of this invention is the mold-release properties of the solid 
product. The chlorinated phenol containing a small amount of a glycol 
ether compound is easily released from the cavity of a corrosion-resistant 
storage receptacle. 
The addition of at least 0.5 weight percent of a glycol ether compound, 
based on the total weight of the crude or distilled molten chlorinated 
phenol, effectively permits the release of stored, solidified product in 
contact with corrosion-resistant substrates, from the substrate using a 
minimal amount of release force. The glycol ether additive also inhibits 
dioxin formation and inhibits decomposition of molten, crude chlorinated 
phenols with or without distillation. 
The glycol ether compounds used as internal release agents in chlorinated 
phenols, according to this invention, include mono-ethers of ethylene, 
diethylene and triethylene glycols; mono-methyl, -ethyl, -butyl, 
-isobutyl, and -phenyl ethers of glycols; and mono-ethers of propylene 
glycols. 
The amount of glycol ether compound employed in the molten chlorinated 
phenol is not narrowly critical and can be varied considerably. The amount 
used depends largely upon the degree of release force desired. Very small 
amounts are effective in providing release properties. There can be used 
as little as 0.5 weight percent based on the total weight of a chlorinated 
phenol. Higher amounts up to 20 weight percent on the same weight basis 
can be used. A preferred range is from 1 weight percent to about 10 weight 
percent on the weight basis given above. 
The addition of the glycol ether compound may be by any suitable means; 
however, it is preferred that the addition be accompanied by agitation, 
stirring or mixing so that a uniform mixture of the glycol ether and the 
chlorinated phenol results. 
Typically, the glycol ether addition is performed at atmospheric pressure 
or above, for example 0 to 50 pounds per square inch gauge. The 
temperature for glycol ether addition can be from about 175.degree. C. to 
about 230.degree. C. The addition temperature is suitably above the 
freezing point of the chlorinated phenol and below the boiling point of 
the glycol ether compound additive. The early addition of the glycol ether 
compound will decrease the amount of tar in the feed, which as noted 
earlier begins to decompose soon after the chlorination reaction is 
terminated. 
The choice of a storage vessel is not critical; however, in the production 
of large quantities (tons) of chlorinated phenol, it is recommended that 
the surface be able to withstand operating temperatures up to about 
230.degree. C. and be corrosion-resistant to maintain the chlorinated 
phenol in a nonroughened manner. By "corrosion-resistant" is meant sturdy 
and resistant to chemical changes (e.g., rusting, oxidizing processes) 
which cause a gradual wearing away or alteration of the surface. The walls 
of the container should be of a suitable thickness to prevent distortion 
of the molds. It is not required but preferred that the vessel surface 
contain a minimum amount of iron. The contact with iron causes the molten 
chlorinated phenol to darken; the degree of darkness depends on the length 
of time it is in contact with the iron. 
Test Methods for Evaluating Mold-Release Properties 
Prior to mixing the glycol ether additives with the molten chlorinated 
phenol, 125 ml cylindrical molds of stainless steel or 
polytetrafluoroethylene-lined steel, measuring 21/2 inches in height and 2 
inches in diameter, are cleaned with water and dried by wiping with a 
clean cheese cloth. A No. 10 wire hook is placed in each clean mold. 
The quantity of glycol ether additive desired for mixing with the 
chlorinated phenol is added to an 8 oz. bottle containing the crude 
chlorinated phenol and heated to about 190.degree. C. with occasional 
stirring until thoroughly blended. The molten glycol ether/chlorinated 
phenol mixture is then poured into the wire hook-containing cylindrical 
mold which is maintained at room temperature (.about.23.degree. C.). After 
a 4-hour cooling period, the wire hook in each sample is independently 
attached to the load-measuring clamp of a Model J Tensile Tester. The 
amount of release force needed to pull the solidified chlorinated phenol 
from the cylindrical mold cavity is measured. 
The Model J Tensile Tester is a brand of Scott Testers distributed by 
GCA/Precision Scientific, Chicago, Ill. and is more fully described in 
Bulletin 330/75, "Constant Rate-of-Traverse Tester, Model J", the contents 
of which are incorporated herein by reference. In Examples 1-7, a 
gear-driven recorder indicates the load in pounds of force (lbf) on a 
direct reading dial and a recording chart. The values recorded in Example 
1 indicate that some adherence, although slight, has occurred. The 
foregoing procedure is used in developing release forces in Examples 1-7. 
In each example the chlorinated phenol is pentachlorophenol.

The following examples illustrate the invention but are not to be taken as 
limiting its scope. In the examples, quantities of material are expressed 
in terms of parts by weight, unless otherwise specified. 
EXAMPLES 1-7 
In Table I below, Comparison A refers to a "Control" where no release agent 
was incorporated into the molten pentachlorophenol. Example 1 refers to an 
experiment where 1 weight percent of 2-(2-butoxyethoxy)-ethanol 
commercially available as DOWANOL.RTM. DB (a trademark of the Dow Chemical 
Company) is incorporated. In Comparison B, materials used as dioxin and 
decomposition inhibitors are examined at the 1 weight percent level. Each 
sample, with and without an additive, is tested after the molten material 
had cooled to room temperature and solidified. 
TABLE I 
______________________________________ 
Mold-Release Tests 
Example/ Release 
Comparison Force 
No. Additive* in lb 
______________________________________ 
1 DOWANOL DB &lt;1 
2 DOWANOL TBH 2 
3 DOWANOL EB &lt;1 
4 DOWANOL DM &lt;1 
5 DOWANOL DE 3 
6 DOWANOL PiB &lt;1 
7 DOWANOL PPh &lt;1 
A None 2 
B PE-200 24 
______________________________________ 
*The chemical composition of each additive is as follows: (DOWANOL.RTM. i 
a trademark of The Dow Chemical Company) 
DOWANOL DB monobutyl ether of diethylene glycol 
DOWANOL TBH monobutyl ether of triethylene glycol and higher glycols 
DOWANOL EB monobutyl ether of ethylene glycol 
DOWANOL DM monomethyl ether of diethylene glycol 
DOWANOL DE monoethyl ether of diethylene glycol 
DOWANOL PiB monoisobutyl ether of propylene glycol 
DOWANOL PPh monophenyl ether of propylene glycol 
PE200 polyethylene glycol (M.W. 200). 
EXAMPLE 8 
Measurement of Decomposition and Dioxin Formation 
A 500 ml flask equipped with a thermometer, heat lamp and controller, 
1".times.1' glass tube condenser connected to a trap containing 100 cc of 
1N sodium hydroxide is prepared to simulate high temperature storage 
conditions. To such prepared flask is added 266.4 grams of crude 
pentachlorophenol, containing residue from a Friedel-Crafts catalyst such 
as aluminum chloride, and 2.7 grams of DOWANOL DB additive. The mixture is 
heated, with stirring, and maintained at 190.degree. C. for about 61/2 
hours. During this 61/2-hour interval, nitrogen is slowly swept across the 
surface and bubbled into the sodium hydroxide trap. One-milliliter samples 
are withdrawn from the trap and titrated for HCl, one of the major 
decomposition products of pentachlorophenol. The titration is accomplished 
with 0.1N silver nitrate to give percent decomposition. The titration 
analysis reveals a small amount of HCl formation; &lt;0.5 percent 
decomposition of pentachlorophenol under the conditions stated. 
An aliquot of the above crude pentachlorophenol is also analyzed for 
chlorodioxin formation. Immediately following the chlorination of a molten 
phenol 1.25 grams of DOWANOL DB is added to 125 grams of crude 
pentachlorophenol, with agitation. Chlorodioxin formation is measured by 
liquid chromatography, at two intervals giving the following results. 
______________________________________ 
Time Dioxins 
(Hrs.) Hexachloro Octachloro 
______________________________________ 
0 &lt;3 ppm 594 ppm 
61/2 &lt;3 ppm 729 ppm 
______________________________________ 
The above data illustrate that glycol ether compounds of this invention not 
only make it possible to produce chlorinated phenol in a form that is 
easily extractable from corrosion-resistant storage vessels but also in a 
form which is very desirable from an environmental and industrial hygiene 
standpoint. The glycol ethers of this invention reduce the time and effort 
necessary to pull solidified chlorinated phenol blocks from the 
corrosion-resistant mold cavity and also inhibit product decomposition and 
toxic dioxin formation therein.