Process for making industrial organic solvents and hydrocarbons used as fuels

Process for marking industrial organic solvents miscible with water and petroleum products gaseous at atmospheric pressure and room temperature and liquid when compressed at low pressure, by the addition to the above solvents of a primary nitroderivative having the general formula EQU R-CH.sub.2 -NO.sub.2

The present invention relates to a process for marking industrial organic 
solvents and petroleum products used as fuels. 
More specifically, the present invention relates to a process for marking 
industrial organic solvents miscible with water, for example alcohols with 
a low molecular weight, and petroleum products which are gaseous at 
atmospheric pressure and liquid when compressed at low pressure, such as 
for example propane, butane, liquefied petroleum gas (GPL) and relative 
mixtures. 
The necessity for marking industrial organic solvents or petroleum 
products, such as fuels and gasolines, derives from the difference in the 
sales price that the same product can have owing to the different taxation 
which can be applied depending on its destination. 
This can lead to situations involving fiscal frauds by using the product 
for different purposes than those for which it is taxed. 
To prevent frauds of this kind industrial organic solvents and petroleum 
products are marked with a suitable substance which permits it to be 
easily identified. 
Substances which can be used as markers should have definite requisites, 
for example they should be stable under operating conditions and be of 
such a nature as to not influence the physico-chemical characteristics of 
the organic solvent or petroleum product, they should be sufficiently 
soluble and preferably to such a degree as to be able to be used also in 
the form of concentrated solutions, they should be difficult to separate 
with physical or physico-chemical methods (unless at uneconomical costs), 
and they should be able to be used in small quantities. In addition, the 
above marker substances should be identifiable with simple, rapid and 
sensitive detection methods. 
For example GPL (mixture of aliphatic hydrocarbons consisting for more than 
95% of propane gas) can be stored, compressed in a liquid phase at 5-10 
Kg/cm.sup.2, in cylinders of about 40 litres or in tanks of various cubic 
metres in volume. GPL is supplied, during use, in gas phase. 
In Italy GPL for domestic (cooker, heating) and industrial use has tax 
facilitations compared to the GPL used for road motor vehicles. 
To avoid similar frauds, a composition is added by law to the GPL for 
domestic use, consisting of: a) furan, in a quantity of from 10 to 50 
p.p.m., detectable in gas phase by reaction with aniline and acetic acid 
on cotton-wool with the formation of a red colouring. This substance 
however has various disadvantages, for example, it is extremely toxic 
(T.L.V.=2 P.P.M.), it is difficult to detect owing to the small quantities 
used, it has a high boiling point (164.degree. C.) which limits its 
presence in gas phase; b) the so-called marker A, a concentrated aromatic 
solution of the yellow azoic dye 
1-[N-ethyl-N-(4',7'-dimethyl-3',5'-dioxa-octyl]-amino-4-phenylazo-benzene. 
This product is used in quantity of 5-20 p.p.m., and is detectable in the 
liquid phase of GPL by reaction on cotton-wool with an aqueous solution of 
hydrochloric acid with the formation of a purplish-red colour. This 
so-called marker A has numerous disadvantages however as it is not 
completely soluble and leaves pitchy deposits in the tanks and decanting 
lines, with consequent problems of cleaning and washing. In addition it is 
drawn in the gas phase during supply and this causes drawbacks due to 
pollution of the operating equipment, for example the formation of 
deposits on compressor membranes and in other critical parts and the 
plastication of seals. 
A process has now been found for marking industrial organic solvents 
miscible with water and petroleum products, gaseous at atmospheric 
pressure and room temperature and liquid upon light compression, which 
overcomes the disadvantages described above. 
In accordance with this the present invention relates to a process for 
marking industrial organic solvents miscible with water and petroleum 
products gaseous at atmospheric pressure and room temperature and liquid 
when compressed at low pressure, which consists in adding to the above 
solvents or petroleum products small quantities of a primary 
nitroderivative having general formula (I) 
EQU R-CH.sub.2 -NO.sub.2 (I) 
wherein R is selected from H, CH.sub.3, C.sub.2 H.sub.5. 
Unlike the marking agents of the known art, the nitroderivates of general 
formula (I) can be easily identified and have the requisites specified 
above. 
The nitroderivatives of general formula (I) can be advantageously used for 
marking industrial organic solvents miscible with water, for example 
methanol, ethanol, iso or n-propanol, glycols, polyols and glycolethers. 
In fact the nitroderivatives of general formula (I) have a good 
miscibility with water (for nitromethane this value is 10.5%, for 
nitroethane from 4.6% to 20%) and consequently they cannot be extracted in 
a heterogeneous aqueous phase as these solvents are also miscible in this. 
The nitroderivatives of general formula (I) can also be used for marking 
gaseous hydrocarbons compressed in a liquid phase at low pressure 
(indicatively at a pressure lower than 10 bars), such as propane, butane 
and GPL. The possible extraction of the nitroderivative of general formula 
(I) from the above hydrocarbons in a heterogeneous aqueous phase would be 
a costly operation as it would require pressure-proof equipment and the 
final anhydrification of the hydrocarbon mixture. 
The nitroderivatives of general formula (I) can be used as such or diluted 
with other inert components. 
If the compound of general formula (I) is nitromethane, it is preferable 
for it to be diluted with desensitizing agents capable of considerably 
reducing its explosive characteristics. 
Nitromethane in fact has the disadvantage of exploding in the following 
three critical conditions: 
a) when it is subjected to violent mechanical shock, higher than that 
caused by a calibre 8 bullet; 
b) when it is subjected to rapid and violent adiabatic compression; 
c) when is it heated, in a closed container, to a temperature close to 
critical temperature (315.degree. C.). 
In mixtures based on nitromethane, the desensitizing agents can be, for 
example, cyclohexane, 1,4-dioxane, 1,2-butylene-oxide, methanol, ethanol, 
isopropanol, 1- and 2-nitropropane, methyl chloroform, toluene, benzene, 
methylene chloride. The above desensitizing agents can be mixed with the 
nitromethane in a minimum recommended quantity of from 25 to 50%. 
Compared to the products of the known art, the nitroderivatives of general 
formula (I) are not toxic, having a TLV of between 100 and 150 p.p.m. In 
addition they are colourless liquids, soluble in hydrocarbons in a 
quantity higher than 2%. 
They can be used as the sole marking product, as they can be detectable 
both in the gas and liquid phase of GPL, the boiling point of nitromethane 
being 101.degree. C., and that of nitroethane 114.degree. C. 
The nitroderivatives of general formula (I) can be used in GPL and in 
industrial organic solvents in a quantity of between 10 and 200 p.p.m., 
preferably between 20 and 100 p.p.m. 
The above nitroderivatives of general formula (I) can be detected in the 
GPL directly on site by means of two different chromatic reactions (method 
A and method B) which give shades of colouring varying from blue to red 
depending on the operating procedure of the test. 
With respect to method A, this is a reaction, valid for all primary 
nitroderivatives, which takes place in the presence of polar solvents in a 
basic environment between the nitroderivative and the diazonium salt of an 
aromatic amine, preferably o-dianisidene (FAST BLUE B SALT), a compound 
which is easily available on the market in powder form. 
The above reaction is cited in literature (Feigl Spot tests in Organic 
Analysis--seventh Edition, page 296) which however indicates conditions 
which give colourings varying from yellow to orange. We, on the other 
hand, have created conditions which give darker shades, depending on the 
type of solvent and the quantity of base: from blue to red for 
nitromethane, from violet-red to orange for nitroethane. 
As far as method B is concerned, this is only valid for nitromethane. 
The reaction takes place in an aqueous medium, at basic pH (from 9 to 12), 
between the nitromethane and 1,2-naphthoquinone-4-sodium sulphonate. 
A chromatic reaction occurs which gives a blue to violet colouring 
depending on the test conditions and above all the solvent mixture. The 
colouring has its maximum intensity and stability at a pH of between 9.4 
and 9.8, but its development is more rapid at higher pHs; the maximum 
absorption is within the range of 565-585 nm. 
The reaction, very sensitive, is described in literature (Turba et 
al.--Angewandte Chemie 1949, Vol. 61/2, pages 74-75; Jones, 
Riddick--Analytical Chemistry, 1956, Vol. 28/9 page 1493 on). The second 
reference indicates the conditions for the spectrophotometric quantitative 
determination in the visible range of the nitromethane. 
With respect to the operating procedure of the tests on site to verify the 
presence of the marker, in the case of GPL the procedure is as follows: a 
cotton flock, soaked in basic reaction solvent, is placed, for 10-20 
seconds, against a stream of GPL removed either in the liquid or gas 
phase. The marker of general formula (I) is extracted and dissolved in the 
basic solvent, and then chromatically displayed by the addition, on the 
cotton flock, of several drops of aqueous reagent solution. 
The following examples provide a better understanding of the present 
invention:

EXAMPLES 
Method A is described in examples 1-6, i.e. the copulation reaction of 
primary aliphatic nitroderivatives with diazonium salt FAST BLUE B SALT 
(FBBS). 
Method B is described in examples 7-9, i.e. the reaction of nitromethane 
with 1,2-naphthoquinone-4-sodium sulphonate (NQS). 
EXAMPLE 1 
100 grams of GPL marked with 50 p.p.m. of nitromethane are bubbled, in 60 
minutes, into a Drechsel 250 ml glass bottle equipped with a porous 
septum, containing 100 grams of mixture consisting of 60 parts of 
N,N-dimethylformamide and 40 parts of a methanol solution of KOH at 2.5%. 
The G.P.L. is directly removed from its compressed liquid phase (8 
kg/cm.sup.2) contained in a 40 litre cylinder filled for 90% of its volume 
(about 18 kg of GPL). 
When the removal has been completed 20 grams of methanol solution at 0.1% 
of FAST BLUE B SALT (tetrazonium salt of 0-dianisidene), freshly prepared 
are added to the bottle. 
A deep reddish-purple colouring develops determined by the copulation 
between the tetrazonium salt and nitromethane transferred to the 
extraction solution. 
EXAMPLE 2 
The test is similar to that described in example 1, with the difference 
that the GPL marked with 5 grams/100 kg of nitromethane is removed 
directly from the gas phase. 
A red colouring develops, a little less intense than that in example 1. 
EXAMPLE 3 
The test is similar to that described in example 1, with the difference 
that the GPL, poured from its liquid phase, is marked with 5 grams/100 kg 
of nitroethane. 
A deep red-orange colouring develops. 
EXAMPLE 4 
A solution is prepared consisting of 100 parts of N,N-dimethyl formamide 
with a low water content (&lt;0.15%) and 0.3 parts of methanol, made basic by 
the addition of 2 parts of KOH in drops which mostly remains undissolved 
as a precipitate. 
A cotton flock, soaked in this solution, is treated for 2-3 seconds with 
the liquid flow of GPL marked with 5 grams/100 kg of nitromethane and 
contained in the cylinder of example 1. 
The cotton flock is then treated with several drops of 0.1% methanol 
solution of FAST BLUE B SALT. 
A deep blue colouring develops immediately. 
A similar colouring but a little weaker appears after the cotton flock, 
soaked in the same solution, has been subjected for 10-15 seconds to the 
flow of the gas phase of the same GPL marked, and then treated with the 
same reagent. 
EXAMPLE 5 
A solution consisting of 100 parts of anhydrous diethyleneglycol 
dimethylether (diglyme) and 0.5 parts of a solution at 13% of KOH is 
prepared. 
Two cotton flocks soaked in this solution are treated respectively, as 
described in example 4, with the flow of the liquid phase and gas phase of 
GPL marked with 5g/100 kg of nitromethane and contained in the cylinder of 
example 1. 
The two cotton flocks are then treated with drops of a 0.1% methanol 
solution of FAST BLUE B SALT. 
In both cases a purple colouring develops which is a little weaker when the 
flock is treated with the gas phase of GPL. 
EXAMPLE 6 
The test is similar to that of example 5, with the difference that the GPL, 
used for treating the two cotton flocks soaked in basic solution, is 
marked with 5g/100 kg of nitroethane. 
A reddish-purple colouring develops on the two cotton flocks, subsequently 
treated with a few drops of reagent, which is a little weaker in the case 
of the flock treated with the gas phase of GPL. 
EXAMPLE 7 
10 grams of ethanol hydrate (95.5%), marked with 50 p.p.m. of nitromethane, 
are mixed with 10 grams of an aqueous solution of Na.sub.2 SO.sub.4 at 
1.5% and NaHCO.sub.3 at 1.5% (pH=9.7). 
5 grams of an aqueous solution at 0.1% of NQS freshly prepared are then 
added. 
Within a few minutes a stable, purple colouring develops, which reaches its 
maximum intensity after 15-20 minutes and with maximum absorption at 574 
nm. 
EXAMPLE 8 
A mixture consisting of 10 parts of an aqueous solution of Na.sub.2 
CO.sub.3 at 4% in water and 5 parts of diglyme, is prepared. 
A cotton flock, soaked in this mixture, is treated for 2-3 seconds with the 
liquid flow of GPL marked with 5g/100 kg of nitromethane and contained in 
the cylinder of example 1. 
The cotton flock is then treated with a few drops of an aqueous solution at 
0.1% of NQS. 
After a few seconds a blue colouring develops which reaches its maximum 
intensity after 5-10 minutes. 
A similar colouring, but a little weaker, appears after the cotton flock, 
soaked in the same solution, has been subjected, for 10-15 seconds, to the 
flow of the gas phase of the same marked GPL, and then treated with the 
same reagent NQS. 
EXAMPLE 9 
A mixture is prepared consisting of 10 parts of a solution of Na.sub.2 
CO.sub.3 at 10% in water and 5 parts of ethylene glycol. 
A cotton flock, soaked in this mixture, is treated for 2-3 seconds with the 
liquid flow of GPL marked with 10g/100 kg of nitromethane and contained in 
a 10 m.sup.3 tank, filled for 90% of its volume with the liquid phase 
(10.degree. C., 6kg/cm.sup.2). 
The cotton flock is then treated with several drops of an aqueous solution 
at 0.1% of NQS. 
After a few seconds a violet colouring develops which reaches its maximum 
intensity after 5-10 minutes.. 
A similar colouring, but with a lesser intensity, appears after the cotton 
flock, soaked in the same solution, has been subjected for 10-15 seconds 
to the flow of the gas phase of the same marked GPL coming from the tank, 
and then treated with the same reagent NQS.