WO2007034501A2

WO2007034501A2 - A novel process for the manufacture of 5-nonyl salicylaldoxime

Info

Publication number: WO2007034501A2
Application number: PCT/IN2006/000003
Authority: WO
Inventors: Suresh Bhikulal Paliwal; Vijay Bhagwanswarup Dr. Mathur; Bhikulal Narsidas Mirani
Original assignee: Star Orechem International Pvt. Ltd
Priority date: 2005-09-21
Filing date: 2006-01-02
Publication date: 2007-03-29
Also published as: CN101326148B; AP2008004424A0; CN101326148A; AP2376A; WO2007034501A3

Abstract

The invention relates to a process for producing 5-nonyl salicylaldoxime that comprises of converting nonyl phenol to a 5-nonyl aldehyde in a two-step reaction using a novel catalyst mixture, followed by the oximation of the said aldehyde using hydroxylamine sulphate, and that the said catalytic process of aldehyde production is the main invention, in that the effective use of the catalyst mixture helps the reaction proceed at a faster and controlled rate which leads to a higher yield of aldehyde, as a result of complete conversion of all the reactants to the final products.

Description

"A NOVEL PROCESS FOR THE MANUFACTURE

OF 5-NONYL SALICYLALDOXIME"

The present invention relates to a process for producing 5-nonyl salicylaldoxime.

Description of the prior Art

Aldehydes and their derivatives are useful in many applications, e.g. in perfumes,

pesticides, stabilizing agents and as intermediates in the preparation of numerous

compounds of industrial importance, including the oximes which are used in

hydrometallurgical extraction processes, especially the aryl aldoxime having long

aliphatic chain like nonyl, dodecyl etc. which provides the hydrophobicity to aryl

aldoxime and consequently, the efficiency as solvent extraction reagent. Aryl aldoxime

or its derivatives are used for the solvent extraction of metals like copper, nickel, zinc,

cobalt etc. In the solvent extraction process of copper, low-grade oxide ore is initially

treated with dilute sulfuric acid (H₂SO₄). Copper and other base metals dissolve as

sulfates. The solution of metal sulfates is then treated with salicylaldoxime solution in

kerosene. Copper selectively reacts with the oxime and is transferred to the organic

phase as a chelate. This reaction favorably takes place at high acidity, pH range of 1.5

to 4.5. The organic phase is then treated with a solution of pure copper in sulfuric acid

of higher concentration, 25 - 35 gpl copper in 160 - 180 gpl sulfuric acid. Pure copper

transfers from organic phase to the aqueous phase. The aqueous solution is then

subjected to the process of electro winning to produce cathode copper of about 99.99% purity. The organic phase with the aryl aldoxime from which copper has been removed

is re-circulated to the extraction stage for treating fresh solution of copper sulfate with

impurities. Since the aryl oxime is used for purification and concentration of copper

ions selectively, it is desirable that the aryl aldehyde and consequently, the aryl

salicylaldoxime, is produced in a pure form free from aryl dialdehydes.

Contaminations in aryl salicylaldoxime also cause emulsification or crud formation at

the interface during extraction process, resulting in loss of solvents and metal in the

raffϊnate. This emphasizes the need for preparation of pure aryl salicylaldoxime.

GB 751845 describes a method for the manufacture of saligenin (o-

hydroxybenzyl alcohol), by reacting phenol with formaldehyde at about 70⁰C, in

presence of a basic alkaline earth metal as a condensing agent like calcium oxide and

an alcohol like methanol as solvent under substantially anhydrous conditions; the yield

of the saligenin is about 50%. US 41501201 disclosed a catalytic process for preparing

2- hydroxy 3-nonylbenzaldehyde from 2-nonylphenol, paraformaldehyde in presence

of a catalyst consisting of anhydrous stannous and / or stannic chloride and an aprotic

binder like 4-picolline, the yield are about 65%.

It is also known from the equivalent patent (GB 1530248) and JCS (Perkin I)

1980 p.1862 et al. that a --CHO group may be selectively introduced into the 2-

position relative to the --OH group of a phenol, by reacting formaldehyde with the

phenol, in the presence of an amine and anhydrous tin chloride. In the latter reference

it is postulated that the tin chloride reacts with phenol to produce a tin phenoxide, which then acts as a catalyst for the introduction of the formyl group into the ring in a

position adjacent to the OH group. The amine is believed to be required to absorb the

HCl which is produced during the formation of the phenoxide and lesser or greater

quantities of amine than are required for this purpose are shown to have an adverse

effect on both yield and selectivity. It is shown that strongly basic amines, which can

form stable complexes with tin phenoxide, are less satisfactory for the reaction.

Support for the mechanism is found in the reaction of formaldehyde with phenol in the

presence of tin phenoxide itself although the yield is only reported as fair.

In another article by some of the authors of the above-mentioned article [JCS

(Perkin II) 1980 P.407 et al.] it is shown that the dehydrogenation of a 2-

hydroxymethylphenol to the 2-formylphenol using a ketone or aldehyde as hydride

acceptor and tin phenoxide as catalyst is adversely affected by the presence of amine.

Furthermore dehydrogenation does not proceed if the aldehyde is aliphatic.

The process considered in the GB 1530248 has a number of disadvantages

particularly for operation on a commercial scale. The presence of formaldehyde and

HCl or the amine hydrochloride salt and the by-product methanol in the same reaction

mixture is expected to lead to the formation of chloromethyl ethers and methyl

chloride, which are carcinogenic. The yield and selectivity of the process also appear

to depend upon the use of about 10 mole % of the tin chloride and up to 40 mole % of

the amine based upon the phenol which would make commercial operation of the

process very expensive and pose serious disposal problems for the effluent. Detail disclosure of the invention

According to the present invention there is provided a process for the

preparation of a nonyl salicylaldoxime, which comprises the reaction in an anhydrous

medium of formaldehyde with nonylphenol magnesium methoxide complex, in the

presence of a tin compound.

The tin compound is conveniently formed, for example tin chlorides, oxides,

hydroxides or nitrates. Tin dichloride (stannous chloride) is an especially preferred as

catalyst. The reaction conveniently takes place in the solvent that is to be used for the

reaction of the formaldehyde and nonylphenol magnesium methoxide complex.

The aryloxy magnesium salt is made from arlyoxy magnesium intermediate.

The arlyoxy magnesium intermediate can be prepared by any of the methods known to

those skilled in the art. Such methods include , reacting magnesium in the form of its

alkoxide, e.g. methoxide ,with a reactant capable of providing the aryloxy group, i.e. a

phenolic compound, such as e.g. paranonyl phenol, in the presence of a non-polar

solvent, to form paranonyl phenol magnesium methoxide complex, which also absorb

the liberated hydrochloride by reaction with tin compound.

In the present invention the rate of formation of magnesium methoxide is

enhances by introduction of a catalyst, stannous chloride in combination with the

another catalyst iodine, already known in the prior art, Journal of Medicinal

Chemistry, (1993) 36(6), pp 758-764 and in US 2965663 processes for preparing metal

alkyls and alkoxides. By use of this catalyst combination the conversion of methanol to methoxide is preferably in the molar ratio of 1.1:1. Although the slight excess of

methanol is maintained in the system to provide fluidity to the reactants, while the

presence of toluene leads to the formation of azotrope (methanol: toluene = 69: 31)

with excess of methanol.

The phenol may be substituted in any or all positions, other than the 2-position,

by groups which do not interfere with the course of the present process and which

preferably are electron repelling or weakly electron attracting.

It has now been found that good selectivity for the formylation of phenols in the

2-position can be achieved in the absence of any carcinogenic by-products by the

reaction of formaldehyde with the para nonylphenol magnesium methoxide complex in

the presence of a relatively low levels of a tin compound, provided the tin compound is

such that, on extraction with water, the aqueous medium has a pH of from 6 to 8.

The substantially anhydrous conditions required by the formylation reaction for

production of the magnesium bis (2-formyphenoxide) may be conveniently provided

by the use of substantially anhydrous reactants together with conventional techniques,

for example distillation, for removal of adventitious moisture. It is usually

advantageous to perform the reaction in the presence of a substantially anhydrous

solvent system. Suitable solvent systems typically comprise an inert non-polar or low

polarity organic solvent and/or a polar organic solvent capable of acting as a legend

with respect to magnesium atoms. Suitable non-polar liquids are for example benzene, toluene, xylene,

mesitylene, cumene, cymene, and chlorinated aromatic hydrocarbons such as

monochlorobenzene, and orthodichlorobenzene. Toluene and xylene are especially

preferred solvents.

Both free gaseous formaldehyde, solutions of formaldehyde in anhydrous

solvent and polymeric forms, such as paraformaldehyde and other conventional

reagents which release formaldehyde may be used in the present process.

Paraformaldehyde is found to be an especially convenient source of formaldehyde. If

high conversion of the phenol is required the molar ratio of formaldehyde to phenol

should be at least in the range 0.5:1 to 4:1 and is preferably in the range 0.5:1 to 1.7:1,

as approximately half moles of formaldehyde being reduced to methanol and other by

products.

The formylation reaction used to prepare the magnesium bis (2-

formaphenoxide) is suitably performed at a reflux temperature within the range from

about 65⁰C to about 90⁰C , by-products of the reaction, for example methanol, methyl

formate and methylal, preferably being removed from the reaction mixture as they are

formed. The reflux temperature, in any particular case, will depend upon the

constitution of the solvent system and upon the pressure being exerted on the reaction

zone. Formylation may be satisfactorily performed at atmospheric pressure.

The aldehyde formed is separated from small quantities of dialdehydes and

other impurities by the use of Short Path Distillation Unit (SPDU) at 160⁰C to 240⁰C under lmm Hg₅ more preferably at 170 to 190⁰C at 0.1mm Hg₅ to obtain high yield of

substantially pure form of 5-nonyl salicylaldehyde. The use of SPDU enables the

purification at low temperature, which prevents the degradation of aldehydes, and

oximes occurring at high temperature during fractionation at about 180 - 200⁰C, as

practiced by other workers.

The process of the present invention is especially suitable for the manufacture

of 5-alkylsalicyladoxime. 5-nonylsalicyladoxime may be prepared from 4-nonylphenol

derived from phenol and propylene trimmer, and consisting of an isomeric mixture

containing straight and branched nonyl groups, by following method.

The present invention is a novel method for the manufacture of 5-nonyl

salicylaldoxime and is more illustrative by the following examples:

Example 1:

A 2 liters round bottom 4 necked flask placed in a suitable heating mantle and

equipped with stirrer, reflux condenser, thermometer and dropping funnel, is charged

with 83g of toluene, 12.6g (0.525 mol) of magnesium powder, 0.06g of iodine and

2.7g of anhydrous stannous chloride. To this under stirring 272g of methanol - toluene

azeotrope, obtained from the previous batch, is slowly added. The reaction mixture is

heated to reflux (about 64°C) for 60 min to ensure the completion of Mg-methoxide

formation. To this 22Og (1.0 mol) of nonyl phenol is slowly added and reflux is

continued for another hour. To this is added 265g of toluene and the temperature raised to 80⁰C at which temperature toluene-methanol azeotrope started distilling. This

distillation is continued till all the azeotrope distilled over.

Further portion of 0.9g of stannous chloride is charged to the above reaction

mass and 33g (0.36 mol) of paraformaldehyde powder is added over a period of 30 to

40 min with a screw feeder. Stirring and temperature of 80⁰C are maintained for

another 120min to ensure complete aldehyde formation.

The product is cooled to about 50⁰C, neutralized with 40% sulfuric acid and

allowed to settle. The lower aqueous layer is treated separately for recovery of

magnesium sulfate and small quantities of magnesium chloride and stannous sulfate.

The upper oily layer is washed free of acid and subjected to molecular

distillation in short path distillation unit (SPDU) at 190⁰C and 0.1mm Hg. The low

boilers are distilled and recycled while the high boilers are used as boiler fuel.

5-nonyl salicylaldehyde overheads are mixed with 25Og of kerosene and

subjected to oximation by the known process.

9 Ig of hydroxylamine sulfate in 182g of water is mixed gently with aldehyde

overheads for 120min at 60⁰C, to this 58g of sodium carbonate in 17Og of water is

added and mixed for 15min. Two layers are allowed to separate; lower layer being

aqueous is drained for effluent treatment and recovery of sodium sulfate.

The oxime in the upper layer is treated with 20% sulfuric acid, to remove

metallic impurities and washed free of acid with demineralised water. The oxime is finally dehydrated in short path distillation unit (SPDU) at 95°C for 240 min at lmm

Hg. Product is 95% by GC.

Example - 2:

Repeat the above experiment, with 4.05g and 1.35g of stannous chloride,

instead of adding 2.7g and 0.9g. The product is about 90% by GC. The difference in %

is due to the formation of more impurities, in comparison to the Example - 1.

Example - 3:

Example - 1 is repeated with 1.35g and 0.45g of stannous chloride instead of

adding 2.7g and 0.9g. The product is about 92% by GC, which is due to the presence

of unreacted nony 1 phenol .

Example - 4:

Example - 1 is repeated without any stannous chloride. The product is about

85% by GC, due to the presence of unreacted reagents.

Claims

We claim:

1. A novel process for the manufacture of 5-nonyl salicylaldoxime, comprising of

the following steps:

a. preparing an intermediate magnesium methoxide by suspending

magnesium powder in toluene and reacting with methanol - toluene

azeotrope, the reaction is carried under reflux condition; the reaction is

accelerated by the using of a mixture of catalyst containing anhydrous

stannous chloride and iodine (SnCl₂-H₂);

b. treating above magnesium methoxide in the second reactor with nonyl

phenol at 64 - 80° C, to give nonyl phenol magnesium complex;

c. adding to the above nonyl phenol magnesium complex anhydrous

SnCl₂ as catalyst and paraformaldehyde powder using a screw feeder

over for 120 min at 80⁰C, to produce formylated nonyl phenol

magnesium complex;

d. neutralizing above formylated nonyl phenol magnesium complex in a

neutralization reactor; with dilute sulfuric acid for about 80 min at 40⁰C.

5-nonyl salicylaldehyde in the organic phase is separated and purified in

a short path distillation unit (SPDU) at 195°C and 0.1mm Hg;

e. obtaining 5-nonyl salicylaldehyde as an overhead in the short^' path

distillation unit (SPDU) which is free from other low boiling and high

boiling impurities; f. transferring 5-nonyl salicylaldehyde to the oximation reactor, blending

with equal amount of kerosene to give fluidity and treating with aqueous

solution of hydroxylamine sulfate and aqueous soda ash over a period of

120min at 60 ⁰C, after complete phase separation aqueous phase is drain

for effluent treatment; treating organic phase containing oxime with 20%

sulfuric acid and washing free of acid with water;

g. dehydrating 5-nonyl salicylaldoxime in SPDU, wherein traces of

moisture and some quantity of solvent (kerosene) are evaporated, time

required is about 240 min at 95 ⁰C at lmm Hg, finally producing 70% 5-

nonyl salicylaldoxime + 30% kerosene;

h. adjusting strength of 5-nonyl salicylaldoxime with modifiers and

additional kerosene as per requirement and stored in storage tanks.

2. A novel process for the manufacture of 5-nonyl salicylaldoxime as claimed

in claim 1 wherein the use of catalyst anhydrous stannous chloride and

iodine yield 95% conversion to 5-nonyl salicylaldoxime.

3. A novel process for the manufacture of 5-nonyl salicylaldoxime as claimed

in claim 1 wherein use of catalyst anhydrous stannous chloride and iodine

increases the rate of reaction to produce end product.

4. A novel process for the manufacture of 5-nonyl salicylaldoxime as claimed

in claim 1 wherein the use of catalyst combination, anhydrous stannous

chloride and iodine during the methoxylation and anhydrous stannous chloride in the formylation step reduce the consumption of methanol and

paraformaldehyde respectively, during the reaction.

5. A novel process for the manufacture of 5-nonyl salicylaldoxime as claimed

in claim 1 produces pure form of 5-nonyl salicylaldoxime of 95% purity and

about 95% yields due to the use of SPDU in purification stage.

6. An improved process for the manufacture of 5-nonyl salicylaldoxime as

claimed in claim 1 produces comparatively low quantities of by products

such as methyl formate, methanol, methalal etc.

7. An improved process for the manufacture of 5-nonyl salicylaldoxime as

claimed is herein described with foregoing description and examples.