Organic compounds -- part of the class 532-570 series – Organic compounds – Azo
Reexamination Certificate
2000-12-19
2002-01-15
Powers, Fiona T. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Azo
C534SDIG002, C008S527000, C044S328000
Reexamination Certificate
active
06339145
ABSTRACT:
The present invention relates to the use of aminic azo dyes and their solutions in organic solvents, as pH depending markers of petrols, gas oils and generally for oil distillation products.
Petrols and gas oils are often additioned with small amounts, from 5 to 40 ppm, of liquid compositions of markers, in order to identify the oil product origin or for fiscal reasons.
The markers in many cases are constituted by liquid compositions of azoic dyes in organic solvents, which generally dye the oil products in yellow.
It is known that the marker control and its identification are carried out by treating a small amount of the oil product, depending on the marker, with an hydrophilic solution of a base or of an acid, which optionally can contain an organic solvent miscible with water.
The marker under these conditions undergoes a pH depending reaction with colour change. The extraction solutions assume more or less intense colorations, with a colour ranging from the red to the violet, to blue.
Among the commercial markers extractable in basic medium Mortrace® SB and ST (Morton) can be mentioned. Among those extractable in acid ambient, Sudan Marker® 455 (C.I. Solvent Yellow 124 -BASF) is known. This latter marker has an high absorbance as defined below, but it has the drawback to be synthetized with an industrially very expensive process, which besides the diazo-copulation reaction requires also an additional process step consisting in the condensation reaction with a vinylether.
Furthermore, other azoaminic markers extractable in acid medium, for example those described in the patent application WO 95/17483, are known. Tests carried out by the Applicant have shown that the azoaminic markers in which the nitrogen substituents are aliphatic groups, in the acid solution have a low specific absorbance E
1%
1
cm, defined as the absorbance referred to a solution at 1% w/v concentration in a 1 cm cell. See the Examples.
The need was felt to have available markers which in the extraction acid solution have high specific absorbance E
1%
1
cm characteristics at the respective wave length of maximum absorption, and obtainable with a simplified process.
The Applicant has unexpectedly and surprisingly found compounds to be used as markers of oil distillation product which overcome the above mentioned drawbacks.
It is an object of the present invention the use as markers of oil distillation product of amino azoic dyes having the general formula
wherein:
R
1
is linear or branched alkyl with a number of carbon atoms from 4 to 20;
R
2
and R
3
are independently H, CH
3
, C
2
H
5
, OCH
3
, OC
2
H
5
;
R
4
and R
5
are independently H, CH
3
, C
2
H
5
;
X is H, OH;
Y is hydrogen or the following poly-isopropoxy chain
wherein n is comprised between 1 and 4; and of their concentrated compositions having a high dry titre in organic solvents, containing from 40 to 100% by weight of said azodyestuffs.
For the use according to the present invention preferably in the formula (I) compounds R
1
is -C
12
H
25
aliphatic radical or sec.butyl, the R
2
and R
3
substituents are independently from each other hydrogen, CH
3
, OCH
3
; R
4
is hydrogen and X is hydrogen or OH, R
5
is hydrogen, Y is H or the radical of formula
1
a wherein n is comprised between 1 and 3
The organic solvent of the compositions having an high dry titre is selected from aromatic hydrocarbons having a number of carbon atoms from 7 to 15, optionally containing one or more C
1
-C
4
aliphatic chains, and mixtures thereof, or solvents having a greater polarity than that of the above mentioned hydrocarbons, comprising in their molecule one or more functional groups containing oxygen, in which oxygen is bound by covalent bonds, such as for example ethers, alcohols, and/or with double bond═
0
such as for example esters, ketones, etc.
Examples of aromatic hydrocarbons usable as azodyes solvents are xylene, alkylnaphthalenes, the aromatic hydro-carbon mixture having from 10 to 11 carbon atoms known as Shellsol® AB; examples of solvents having a polarity greater than that of the aromatic hydrocarbons and comprising in the molecule one or more functional groups containing oxygen are 2-butoxyethanol, butylcellosolve acetate and diacetonalcohol.
According to the object of the present invention the compounds of formula (I) are extracted from the oil product by means of acid solutions of strong, inorganic and/or organic acids, having the following composition (% by volume):
from 5 to 90% of an aqueous solution of a strong acid, having a molarity equal to or higher than 0.5 M;
from 95 to 10% of an hydrosoluble organic solvent.
The extraction phase if necessary can be repeated more times in order to completely extract the marker. Examples of strong acids are halohalide acids, sulphuric acid, nitric acid, phosphoric acid; mono-, di-, tri-chloroacetic acid.
Examples of hydrosoluble organic solvents are alcohols such as methylic, ethylic, isopropylic alcohol; polyols as mono-, di-, polyethylenglycols, glycerine; ether-alcohols such as methoxy- ethoxy-, butoxy-ethanol; dimethylformamide, di-methylsulphoxide.
Optionally an additive can be added, soluble in the acid mixed aqueous/organic phase used for the extraction, to decrease the background coloration of the extraction solution. For example a salt in amount from 5 to 20% w/v can be used. Examples are KCl, CaCl
2
, ZnCl
2
, ZnSO
4
, AlCl
3
.
In the extraction tests carried out by the Applicant to show the advantages obtainable with the use of the present invention markers, in a first series of tests, solutions obtained by diluting in isooctane the marker concentrated liquid compositions up to concentration 5-20 ppm, have been used. These yellow-coloured solutions have a wave length at the absorption peak &lgr;
max
in the range 395-410 nm. The extraction acid solutions have a magenta red colour with &lgr;
max
in the range 530-545 nm. The tests reported in the examples show that the invention markers in the extraction acid solutions have a very high specific absorbance E
1%
1
cm, the concentration of the azoic compound being equal, in particular higher than 50%, in comparison with the above mentioned azoaminic markers.
For example the specific absorbance E
1%
1
cm of the N-ethyl-N- (2-hydroxyethyl)-4-[(dodecylphenyl)-azo]-m-toluidine compound, in concentrated liquid composition at concentration 0.1 moles/70 g, is 775 (&lgr;
max
=538 nm) in the acid hydroalcoholic solution used for the extraction (HCl 10N/ethanol 50/50 v/v), while the one of the composition containing N,N-diethyl-4-[(dodecylphenyl)-azo]-m-toluidine is 424 (&lgr;
max
=535 nm). See Table 1 (in the Table the marker concentrations in the concentrated liquid compositions are 0.1 mole/70 g of composition, calculated by supposing a synthesis yield of
In a second series of tests the marker concentrated compositions have been added to the oil product (gas oil for autotraction, see the Examples) to give marker concentrations in the range 0.5-10 ppm. The extraction has been carried out as described above. The extraction solution coloration moves towards &lgr;
max
values lower than the previous ones, up to about 480 nm, towards the red and orange since the background colour is present. However the peak corresponding to the maximum absorption wave length results clearly identifiable also under these conditions.
Without to be bound to any theory, the Applicant thinks that the greater specific absorbance of the markers of the present invention is due to the association between the hydroxyl group which are in the nitrogen substituent aliphatic groups of these compounds and the organic solvent in the extraction solution.
The markers of the present invention have in the extraction solvent an high absorbance comparable, the concentration being equal, with that of Sudan Marker® 455. However the present invention markers are obtainable with a simpler process, as described hereinunder.
It has been found by the Applicant that formula (I) compounds wherein R
1
=C
4
H
9
, are extractable also with aqueous a
Powers Fiona T.
Societa' Italiana Additivi per Carburanti S.r.l.
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