US3052531A

US3052531A - Fuel composition

Info

Publication number: US3052531A
Application number: US711182A
Authority: US
Inventors: Robert G Jackson; Philip J Garner
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1957-02-01
Filing date: 1958-01-27
Publication date: 1962-09-04
Anticipated expiration: 1979-09-04

Description

United States Patent ware No Drawing. Filed Jan. 27, 1958, Ser- No. 711,182

Claims priority, application Great Britain Feb. 1, 1957 3 Claims. or. 44-69) This invention relates to liquid hydrocarbon fuel for spark-ignited internal combustion engines and to antiknock and scavenger concentrates for use in such a fuel.

Hydrocarbon fuels such as gasoline usually contain an organo-lead antiknock compound, usually a tetraalkyl lead compound such as tetraethyl lead, to increase the octane number of the fuel.' Such lead compounds, however, are prone to cause deleterious engine deposits and to lessen this a lead scavenger is usually needed in the: fuel if it is to be suitable for use in a spark ignited engine. Such a lead scavenger is a compound or a mixture of compounds which facilitates the removal of solid products of combustion before they can accumulate as deposits in the engine. The only lead scavengers which have so far found general application are the halohydrocarbon scavengers, generally consisting of ethylene dibromide or a mixture of ethylene dibromide and ethylene dichloride.

In spite of the wide use of halohydrocarbon scavengers, it is known that these compounds suffer from a tendency to increase engine wear, especially during low temperature operation as is encountered during stop-and-go driving, possibly because they contain large proportions of halogen which may form acidic products of combustion. Heretofore, however, no practical substitute for the halohydrocaroon scavengers has been known and since their omission leads to early spark plug and exhaust valve failures the wear problem has been accepted as the lesser of a number of evils.

It is accordingly a principal object of the invention to provide an improved fuel composition for spark-ignited internal combustion engines. Another object is to provide an improved scavenging composition for use in leaded fuels for such engines. Another object is to provide an improved antiknock concentrate, containing a lead antiknock compound and a scavenger therefor, which is suitable for addition to gasoline. will be apparent in the description of the invention.

We have now discovered a new lead scavenger which can be substituted for the conventional halohydrocarbon scavenger in leaded gasoline to provide effective scavenging action and at the same time to eliminate the deleterious effects of halohydrocarbon scavengers. Moreover, besides this advantage in our scavenger, we have found that leaded gasoline containing our scavenger but no halohydrocarbon scavenger is superior in a number of other respects. Most importantly such a leaded gasoline forms even less combustion chamber deposits and concomitantly leads to reduced engine octane requirements.

It is well known that as deposits collect in the combustion chambers of a spark-ignited engine the octane requirement of the engine gradually rises until the deposits reach an equilibrium level. It takes in the order of 50 to 100 hours of operation for an originally clean engine to reach an equilibrium octane requirement. The difference between the clean engine octane requirement and the equilibrium octane requirement is called the octane requirement increase or increment, usually abbreviated CR1, and is a function of the fuel used and the amount and character of the combustion chamber deposits it forms. One of the surprising advantages of the fuel composition of the invention is the reduced OR-Is obtained with it as compared with conventional fuels.

Still other objects 4 ice The fuel composition of the invention is a hydrocarbon fuel such as gasoline containing an organo-lead antiknock compound such as tetraethyl lead and, as the lead scavenger, certain proportions of one or more boron compounds and one or more sulfur compounds.

Suitable boron compounds range from the simple inorganic boron compounds, such as orthoboric acid, containing relatively large proportions of boron to the organic boron compounds which contain smaller proportions of boron. The boron compound should however have a boron content of at least 1% by weight, preferably at least 2% by weeight and more especially at least 5% by weight. It should be a solid or a liquid at normal temperatures and dispersible or preferably soluble in gasoline in the concentration used. The boron compound preferably contains no elements other than boron, oxygen, carbon and hydrogen, although the presence of sulfur, phosphorus, nitrogen and/ or metal (especially alkali or alkaline earth metal) atoms will generally not be harmful.

Among the inorganic boron compounds, orthoboric acid is perhaps the simplest, least expensive and most suitable for the purposes of the invention; however salts of the various oxy-acids of boron, in particular the alkali metal and alkaline earth metal salts of such acids, are quite suitable, for example calcium orthoborate,

and sodium tetraborate, Na B O Generally the inorganic boron compounds are solids and are not sufliciently soluble in gasoline so their incorporation in the gasoline composition of the invention, in a finely-divided form, can be advantageously effected by means of dispersants. Many techniques and dispersants for incorporating finelydivided solids in hydrocarbon liquids are well known and these are suitable for the purposes of the invention.

Many organic boron compounds are soluble in hydrocarbon oils and are for ths reason preferred over the inorganic boron compounds. The simplest organically combined boron, i.e., organic boron compounds, which can be used in the compositions of the invention are the esters of the oxy-acids of boron, in particular the alkyl esters, especially of boric acid. It is known that the hydrolytic stability of these esters varies considerably with the nature of the alkyl radical and for this reason the trialkyl esters derived from alcohols having not less than 5 carbon atoms in the molecule such as triamyl borate, trihexyl borate, triheptyl borate, trioctyl borate, trinonyl borate, tridecyl borate and tridodecyl borate are preferred. The trialkyl ester-s derived from branched chain alkanols are particularly suitable and examples of such borates are tri(methylisopropylcarbinyl)borate and tri-(di-isobuty1carbinyl)borate. A particularly preferred type of boric ester is derived from boric acid and an alkane diol, such as 2,4-pentanediol, ZanethyI-ZA-pentanediol, 2,4-dimethyl-2,4-pentanediol and 2,4-dimethyl-2,4-hexanediol. Such compounds are described in Darling et al., US. 2,741,548 and the British Patents Nos. 722,537 and 722,538, for example the mono-acid cyclic diester of boric acid and 2methyl-2,4 pentanediol and the ethyl and octyl ester of this mono-acid cyclic diester.

Other organic boron compounds which can be used in the compositions of the invention are the alkyl boronic acids and the dialky-l borinic acids. The hydrolyti-c and oxidation stability of these compounds also varies considerably with the nature of the alkyl radical and it is clear that in the compositions of the invention the compounds having the best stability characteristics are preferred. Specific examples of suitable alkyl boronic acids are the alkyl boronic acids containing an alkyl group of 6 to 8 carbon atoms directly attached to the boron atoms such as n-hexyl-boronic acid and Z-ethylhexylboronic acid,

3 and other such compounds described in Darling, US. 2,710,251. Sui-table dialkyl borinic acids are di-n-butylborinic acid, diisopropylborinic acid, dimethylborinic acid and di-n-hexylborinic acid.

The esters of the alkylboronic and 'dialkylborinic acids can also be used in the compositions of the invention. Suitable esters of alkyl boronic and dialkyl borinic acid are the esters derived from methanol, ethanol, n-butanol, isopropanol, pentanol, and phenol, for example the compounds described in Arimoto, US. 2,720,448 and Arimoto, U.S. 2,720,449. Particularly preferred are the cyclic esters of an alkylboronic acid and an alkane diol some of which have been described in the British Patent No. 722,537. These cyclic diesters may be derived from an alkanediol having from 2 to 8 carbon atoms and an alkylboronic acid having from 6 to carbon atoms. These esters have particularly good stability to oxidation and hydrolysis.

Still other organo-boron compounds which can be used in the compositions of the invention are boronic and borinic acids of the general formula R B(O I-I) in which the symbol R represents a cyclic radical directly linked to the boron atom by means of a carbon atom which is part of the ring structure, In and n are whole numbers from 1 to 2 inclusive, the sum of m and n being equal to 3, as well as the anhydrides and salts of their acids.

The cyclic radical R of the boron compound may be an aryl, cycloaliphatic, or heterocyclic radical, and may contain one or more substituent atoms or groups, such as methoxy, ethoxy, ester, hydroxyl, amine, nitrile, nitro groups, or halogen atoms.

Examples of suitable cycloaliphatic radicals are cyclopentyl, cyclohexyl, methylcyclopentyl, methylcyclohexyl, chlorocyclohexyl, cyclopentenyl and cyclopentadienyl. Examples of suitable heterocyclic radicals are pyridyl, picolyl, pyrryl, indolyl, carbazolyl, furyl, thienyl, thianaphthyl, benzofuryl and dibenzofuryl.

The cyclic radical is preferably a substituted or unsubstituted aryl radical such as a phenyl, methyl-phenyl, hydroxyphenyl, methoxyphenyl, dimethoxyphenyl, chlorophenyl, methylchlorophenyl, trifluoromethylphenyl, phenylphenyl, benzoylaminophenyl, naphthyl, methylnaphthyl, methoxynaphthyl, chloronaphthyl, nitronaphthyl, aminonaphthyl, fluorenyl, anthryl or phenanthryl radical. More especially, aryl radicals containing only carbon and hydrogen atoms are preferred, particularly the hydrocarbyl phenyl radicals. The cyclic radical should contain at least 4 carbon atoms but no more than 14 carbon atoms, and preferably from 6 to 8 carbon atoms.

Arylene diboronic acids such as phenylene diboronic acids, for example, phenylene-l,4-diboronic acid, and naphthalene diboronic acids, for example, naphthalenel,4-diboronic acid and diarylborinic acids such as diphenyl and ditolylborinic acids and the anhydrides or salts of such acids may also be employed.

Salts of the boronic and borinic acids hereinabove specified may be used, particularly the ammonium salts thereof, including both hydrocarbyl aryl or alkyl N-substituted or unsubstituted ammonium salts, such as for instance, bis(di-2-ethylhexylammonium) phenylboronate. The salt-forming group should have no more than 14 carbon atoms, preferably no more than 8 carbon atoms. The preferred acids andsalts which are used in this invention are those which are stable in the presence of water.

The esters of cyclic boronic acids and dicyclic borinic acids such as the alkyl esters of phenylboronic acid and diphenylborinic acid can also be used in the compositions of the invention, for example the compounds described in Arimoto, U.S. 2,720,448 and Arimoto, US. 2,720,449. Suitable compounds of this type are dimethyl phenylboronate, diisopropyl phenylboronate, methyl diphenylborinate, ethyl diphenylborinate, isobutyl diphenylborinate, and n-butyl di-p-tolylborinate.

Other boron compounds suitably used in the compositions of the invention are alkanolamine esters of boronic and borinic acids, borazoles, and boric acid polyesters prepared by esterifying boric acid with polymeric compounds containing a plurality of non-acidic hydroxyl groups such as those polymeric compounds having a molecular weight of at least 1000 and prepared by copolymerization of a C alpha olefin and a polymerizable compound containing a hydroxyl group or a group which can be easily hydrolyzed into a hydroxyl group.

Just as the presence of a substantial proportion of boron is the main essential characteristic of the boron compound, the sulfur compounds suitably used in the compositions of the invention are mainly characterized essentially only by the presence of sulfur. They should, however, boil within the gasoline boiling range and be gasoline soluble, and are preferably organic sulfur compounds. The sulfur compounds which occur naturally in gasoline fractions, preferably those remaining after treatment to remove or convert malodorous and unstable compounds, are eminently effective and comprise the most economical and convenient sulfur compounds for the purposes of the invention. Such naturally occurring sulfur compounds may include the alkyl mercaptans such as methyl and ethyl mercaptans, the alkyl sulfides, or dialkyl thioethers, such as diethylthioether and diisopropylthioether, dialkyl disulfides such as dimethyl disulfide, methyl ethyl disulfide and diethyl disulfide, cycloparaffinic sulfides such as thiocyclobutane, thiocyclopentane, thiocyclohexane and thiocycloheptane, and thiophenes such as thiophene, Z-methylthio-phene, 3-methyl-t-hiophene, 3-ethylthiophene, 2,4-dimethyl-thiophene and butylthiophene, and thiophthene, thionaphthene and benzothiophene. Of course mercaptans are malodorous and are usually removed or converted to disulfides during the refining of hydrocarbon fuels, and for this reason the preferred fuel compositions of the invention are doctor sweet, i.e., mercaptan-free.

In some cases there will be insufficient sulfur in the gasoline to supply the necessary amounts for the purposes of the invention, 'which amounts will be explained below. In such cases it will be necessary to add sulfur to the gasoline or to the antiknock or scavenger concentrate to prepare the compositions of the invention. Here certain other preferences as to sulfur compounds become important because while it is often diflicult or expensive and impracticable to change the character of naturally occurring sulfur compounds in gasoline, it is of course practicable and desirable to select carefully sulfur compounds for addition to gasoline. The most important consideration in sulfur compounds to effect the purposes of the invention is to avoid deleterious side effects, especially odor and lead susceptibility. Some sulfur compounds are more antagonistic than others toward the antiknock effectiveness of organo-lead antiknock compounds. In view of these considerations thiophcne and its alkyl-substituted homologues are preferred in the compositions of the invention, even when the naturally occurring sulfur in the gasoline is sufiicient, but most especially when sulfur is to be added. However, such deleterious side effects can be substantially avoided when the sulfur compounds of the compositions of the invention are largely compounds in which the sulfur occurs in a CSC linkage, preferably in a cyclic group and particularly in a five-member ring. Such preferred sulfur compounds used in the necessary concentrations in the compositions of the invention have a substantially negligible effect on the antiknock effectiveness of the lead antiknock compound present. As an additional preference, the sulfur compounds are most suitably those which contain no atoms other than carbon, hydrogen and sulfur.

The concentrations of the boron and sulfur compounds in the compositions of the invention can best be expressed in terms of atomic proportions or chemical equivalents of boron and sulfur in respect to the lead in the lead antiknock compound. Thi is because it is the combustion product compounds of lead which are prone to cause deleterious deposits in the engine, and because the combined effect of the element boron in the boron compounds and the element sulfur in the sulfur com pounds overcomes thi deleterious effect of the lead. It has become a universal custom to express the concentrations of the conventional halohydrocarbon scavengers, ethylene dibromide and ethylene dichloride, in terms of theories, which is merely a convenient way of stating the number of chemical equivalents of the active elements in the mixture (in this case bromine and chlorine) per chemical equivalent of lead, based on the simplest assumed product of a chemical reaction between such elements and lead (in this case lead dibromide and lead dichloride). In accordance with this custom, and to provide a more meaningful description of the compositions of the invention, the concentrations of the boron compounds in the lead-containing compositions of the invention will be described in terms of theories of boron (or theories of boron compounds, which means the same thing) based on an assumed reaction of boron with the lead in the lead antiknock compound present to form the end product lead orthoborate, Pb (BO Thus 1 theory of one or more boron compounds is an amount, in any given quantity of the composition, which provides 2 gram atoms of combined boron per 3 gram atoms of lead in the lead antiknock compound present in that quantity of the composition. Similarly, the concentrations of the sulfur compounds in the lead-containing compositions of the invention will be described in terms of theories of combined sulfur based on an assumed reaction of sulfur with the lead in the lead antiknock compound present to form the end product lead sulfate, PbSO Thus 1 theory of one or more sulfur compounds is an amount, in any given quantity of the composition, which provides 1 gram atom of sulfur per gram atom of lead in the lead antiknock compound present in that quantity of the composition.

The compositions of the invention must contain at least 0.1 theory of one or more boron compounds as described above, and preferably at least 0.5 theory, especially at least 0.8 theory. While concentrations as high as 5.0 theories are sometimes advantageous, it is normally neither necessary nor desirable to use more than 3.0, or preferably 1.5, theories. Concentrations in the range of 1.0 to 1.3, especially about 1.2, are optimum in certain respects.

The sulfur concentration in the compositions of the invention must be at least 0.5 theory such as from 0.5 to 6.0 theories, and preferably at least 2.0 theories. Even more effectively, the compositions will contain at least 10 theories of sulfur, for example from 10 to 15 theories. It has been found that when too little sulfur is present the deposits on the hotter parts of the engine are likely to be of a fused or highly adherent character, resulting in early failure of the spark plugs and exhaust valves. At the higher concentrations of sulfur, however, the deposits obtained in the use of the gasoline composition of the invention are present in only minor quantities and are powdery and easily removed. Thus at high sulfur levels the R1 of an engine operated on the gasoline composition of the invention is much smaller than at low sulfur levels.

While it is greatly to be preferred that the compositions of the invention contain no halohydrocarbon compound, extremely minor amounts, much less than the conventionally used concentrations of 1.0 or 1.5 theories, can be present without materially detracting from the benefits of the boron and sulfur combination scavenger of the invention, for example 0.01 to 0.1 theory, but in no case should the concentration of any halohydrocarbon compound present be over 0.2 theory.

EXAMPLE I As already mentioned the substitution of a boron for the conventional halohydrocarbon scavenger in a leaded gasoline containing the necessary concentration of sulfur reduces engine wear. This was shown in a Petter engine which was run under constant load at 1100 rpm. The piston was fitted with a top ring which had been made radioactive. The wear rate was measured by counting increase in the number of the radioactive pulses per second from the abraded metal which was suspended in the lubricating oil. The lubricating oil used in the first series of tests was a solvent refined lubricating oil derived from a Venezuelan crude oil. The base fuel was a catalytically cracked gasoline of Middle East origin, containing 1.8 ml. of tetraethyl lead per imperial gallon and 12 theories (0.11% by weight) of naturally occurring sulfur, but no halogen scavenger compound. To one part of this base fuel 1 theory of phenyl boronic acid anhydride was added (Fuel A); to another part of the base fuel 0.5 theory of ethylene dibromide and 1.0 theory of ethylene dichloride were added (Fuel B). As can be seen from the results, given in Table I, the fuel composition of the invention, Fuel A, gave a much lower wear rate than the conventional fuel, Fuel B:

A second series of tests was made exactly as the above series except that an additive lubricating oil was used, consisting of a mineral lubricating oil plus basic calcium sulfonate to a 0.1% sulfated ash and a calcium salt of a condensation product of octylphenol and formaldehyde to a 0.3% sulfated ash. As can be seen from the results, given in Table II, the superiority of the fuel composition of the invention was established even in the presence of basic lubricating oil additives which are normally added to reduce corrosive wear. In this case each of the values given is an average of two replicate tests:

Table II Pulses/see/honr Fuel A Fuel B At 30 C. jacket temperature 6.0 23. 8 At 0. jacket temperature..- 2.9 5. 8

EXAMPLE 11 Table III PETTE'R SIDE-VALVE ENGINE OPERATING CONDITIONS Duration: hours. Cycle (repeated):

1 min., 22.8 sec. at 1000 -r.p.n1. (idle). '8 min., 38.7 sec. at 2000 rpm. /2 throttle); 43.2

sec. at 2350 rpm. throttle). 2 min., 21.3 sec. at 2500 rpm. (full throttle).

The base fuel used in the tests was a gasoline containing 1.5 ml. tetraethyl lead per imperial gallon and 12 theories (0.11% by weight) of naturally occurring sulfur, but no halogen scavenger compound. To one portion of the base fuel was added 1.0 theory of ethylene dibromide which became thereby a conventional leaded gasoline composition. To other portions of the base fuel were added various concentrations of phenylboronic acid, as are shown in Table IV, below. At the end of each test the amount of combustion chamber deposits obtained was weighed. Two tests were made on each fuel composition; the results are given in Table IV:

Table IV Scavenger Combusconccntion Test Added scavenger tration, chamber theories deposits,

grains 1 Ethylene dibromide 1. 5.00 .do 1. 0 4. 76 Phenylboromc aei 0. 1 3. 77 0.1 4.37 0.5 6.09 0. 5 4. 08 1.0 3. 28 1.0 4.46 1.5 2.50 1. 5 3. 70

EXAMPLE III In another series of tests to compare conventional fuel compositions with the fuel compositions of the invention, a diiferent gasoline base fuel was used in the same Petter side-valve engine cyclic test procedure described in Example II. In this case two levels of tetraethyl lead (TEL) concentrations were used, with halohydrocarbon scavenger where present being a mixture of 0.5 theory of ethylene dibromide and 1.0 theory of ethylene dichloride. The boron compound again was phenylboronic acid. In this series of tests not only were the combustion chamber deposits measured, but visual observations were made of the piston deposits by disassembly of the engine at the end of each test. The piston cleanliness was rated on a scale of 10, a completely deposit-free piston in the indicated area being assigned a rating of 10, and one completely covered with heavy deposits being given a rating of 1. The results obtained were as fol-lows:

In order to establish that the results obtained in the previous examples do not depend upon combustion chamber configuration or the kind of base gasoline, similar cyclic tests were made with cylinder head-s from several commercial automobiles, i.e., the Triumph TR. 2, the Standard Vanguard and the Vauxhall Wyvern, and with various leaded base fuel mixtures of catalytically cracked gasoline, catalytic reformates, alkylates, and straight run components. In each engine and with each base gasoline the boron compound-sulfur compound combination gave less engine deposits than the halohydrocarbon scavenger.

EXAMPLE v It might be expected in view of the results obtained as set out in the previous examples that the boron-sulfur scavenger combination would improve leaded gasoline already containing a halohydrocarbon scavenger. One of the most interesting and important properties of the boron-sulfur scavenger combination is that this is not the case; in fact, surprisingly, the presence of a halohydrocarbon scavenger turns the benefit of the scavenger combination of the invention into a detriment. This was found in a series of Petter engine tests run exactly as described in Example II, the base fuel being the same (1.5 ml. TEL per imperial gallon, 12 theories sulfur, no halogen scavenger) and with the concentrations of added ethylene dibromide and added phenylboronic acid as indicated in Table VI, below. It will be noted that the addition of increasing concentrations of the boron compound to the base gasoline already containing the halohydrocarbon scavenger actually resulted in the detriment of increasing the ORI; while the addition of increasing concentrations of the boron compound to the base gasoline in the absence of a halohydrocarbon scavenger beneficiall y reduced the ORI. It Will be noted that these tests also show that the elimination of the halohydrocarbon scavenger from the conventional gasoline containing no boron compound results in a detrimental increase in ORI, as would be expected.

The sulfur content of the gasoline composition of the invention is very important. Unless a substantial amount of sulfur is present, the absence of a halohydrocarbon scavenger allows the boron compound to form glassy or fused, and highly adherent deposits on the hotter parts of the combustion chamber, especially the spark plugs and exhaust valves, leading to early failure of these parts. If however sulfur is present in the substantial amounts described above, the deposits are soft and powdery even in the absence of a hal'ohydrocarbon scavenger and do not prematurely attack the combustion chamber parts. This is shown in the following tests on a Ford Consul engine, which was run under high duty cycling conditions on gasoline containing 3.5 ml. of tetraethyl lead per imperial gallon but no halogen scavenger compound, 1.0 theory of phenylboronic acid anhydride and varying proportions of sulfur compounds. The sulfur was added in the form of naturally occurring sulfur compounds by blending the base gasoline with a fraction of a Middle East crude oil with a high sulfur content. The fuels were compared by measuring the number of spark plllg failures due to bridging of the spark plug electrode gap during a running period of hours. The results are given in Table VII:

EXAMPLE VII In another series of tests the effect of varying sulfur content was again determined. In these tests the base fuel was 35% by volume of catalytically cracked gasoline having a final boiling point of 100 C., 12% by volume of an alkylate, and 53% by volume of a catalytic reformate, and also containing 1.5 ml. of tetraethyl lead per imperial gallon, but not halogen scavenger. The sulfur content of the base gasoline was 0.009% by weight, corresponding to 1.0 theory sulfur. To one portion of this base gasoline was added 0.5 theory of ethylene dibromide and 1.0 theory of ethylene dichloride, to establish a base line (Composition 1). To each of three other portions was added 1.0 theory of the boric acid polyester used in Composition 6 of Example VIII, below. Then to two of these latter three portions were added sufiicient quantities of butylthiophene to increase the sulfur content to 3.0 and 5.0 theories sulfur, respectively.

These fuel compositions were each tested by the same simulated road test described in Example VIII below, the results of which tests are given in Table VIII:

Many other boron compounds have been tested and found to be as effective in the compositions of the invention as are the phenylboronic acid and th phenylboronic acid anhydride. For example, in one series of tests the base gasoline was a catalytically cracked gasoline, derived from Middle East crude oil, having a final end boiling point of 205 C., and containing 1.5 cc. of pure tetraethyl lead per imperial gallon but no halogen scavenger, and 15 theories of naturally occurring sulfur compounds. To one portion of this fuel 0.5 theory of ethylene dibromide and one theory of ethylene dichlorid were added as a scavenging agent (Composition 1). To 4 other portions of the same fuel various boron compounds were added in a proportion of 1 theory With respect to the lead content of the fuel.

The boron compounds used in these compositions were as follows.

In Composition 2: Phenylboronic acid hydride.

In Composition 3: Tri(diisobuty1 carbinyl) borate.

In Composition 4: Octylboronic acid.

In Composition 5: N-tris(2-propyl)-B-trimethylborazole.

In Composition 6: A boric acid polyester prepared by reaction of boric acid and a hydrolyzed copolymer of C C alkenes and vinyl acetate containing 17.3% by weight of hydroxyl groups.

All six compositions were engine tested by means of a simulated road test in a spark-ignited single cylinder overhead valve engine of 470 cc. having a compression ratio of 8.5 1. The tests were carried out for 96 hours in cycles of 7 minutes each consisting of 1 minute at full throttle (2,500 r.p.m.), 0.5 minute at throttle (2,250 r.p.m.),

4.5 minutes at half-throttle (2,000 rpm.) and 1 minute at idling speed (800 r.p.rn.). The temperature of the cooling water and of the l bricating oil was 70 C. throughout all tests. After running for 96 hours on each of the six compositions specified above, the engine was dismantled, and the cylinder deposits collected and weighed. The results of the tests are presented in Table IX:

Table IX Composi- Added scavenging agent Deposit tion wei (a) 1 Ethylene dibromide plus ethylene dichloride" 7. 0 2 Phenylboronie acid anhydride 3.96 'Iri-(diisobutyl carbinyl) borate 3. 38 Octylborom'c acid 5. 92 N-tris (Z-propyl)-B-trimethylborazol 4. 88

Boric acid polyester 4. 6

EXAMPLE IX An automotive gasoline composition consisting of 30% by volume catalytically cracked gasoline, 45% by volume catalytic reformate, 10% by volume of a sulfuric acid alkylate of isobutane and butylenes, 5% by volume diisopropyl ether, and 10% by volume normal butane and also containing 1.5 ml. tetraethyl lead per imperial gallon, 5.0 theories sulfur consisting of 1.0 theory naturally occurring sulfur and 4.0 theory of added Z-methylthiophene, and 1.0 theory of orthoboric acid incorporated in the form of a fine dispersion stabilized with a minor amount of a dispersant, but containing no halohydrocarbon scavenger, when tested by the simulated road test described in Example II, will give lower engine deposits of a powdery nature, and lower ORI than either the same composition containing the conventional halohydrocarbon scavengers (ethylene dibromide or a mixture of this compound with ethylene dichloride) at 1.0 or 1.5 theories instead of the boron compound or in addition to the boron compound.

In a further embodiment of the invention it has been discovered that the presence of a phosphorus compound in the compositions of the invention reduces to some extent the amount of sulfur which must be present to avoid the formation of deposits of a harmful character. It is possible to reduce the sulfur content to as low as one-half of the sulfur theory concentrations mentioned previously if the concentration of phosphorus in the composition, expressed as theories of phosphorus, is at least one-quarter that of the omitted sulfur. As has become conventional in the art, the theory concentration of one or more phosphorus compounds is based on an assumed reaction with lead to form lead orthophosphate, Pbg (PO that is, one theory of phosphorus is an amount, in any given quantity of a composition containing a lead antiknock compound, which provides 2 gram atoms of phosphorus per 3 gram atoms of lead in the lead antiknock compound present in that quantity of the composition.

Thus, instead of a minimum of 0.5 theory of sulfur, the compositions of the invention may contain as littl as 0.25 theory of sulfur if at least 0.25/4, or 0.06 theory of a phosphorous compound is present. It is preferred however that at least 0.2 theory for example about 0.3 theory, of phosphorous be present when the sulfur concentration is less than 2.0 theories, and concentrations of phosphorus above 1.5 theories are generally to be avoided in any case.

The nature of the combined phosphorus, i.e., the phosphorus compound or compounds, suitably used in the compositions of this embodiment of the invention is quite varied. Generally any phosphorus compound is suitable as long as it is gasoline soluble, although the preferred compounds are the organic, preferably hydrocarbyl, derivatives of the oxides hydrides and sulfides of phosphorous containing no element other than phosphorus, oxygen, sulfur, carbon and hydrogen, such as the cyclic and acyclic hydrocarbyl phosphates, phosphites, phosphonates, phosphinates, phosphenates, phosphonites, phosphinites, phosphenites, phosphoranoates, phosphoranedioates, phosphoranetrioates, phosphoranetetroates, phosphoranepentoates, phosphines, phosphine oxides and the thio (both thiono and thiolo) analogues thereof. The sulfur free, simpler compounds are of course preferred, i.e., those of the above classes containing only hydrocarbyl groups having up to 10 carbon atoms each, especially the alkyl, alicyclic and aryl phosphates, phosphites and phosphines. Examples of particularly preferred such compounds are the trimethyl, triethyl, tripropyl, and tributyl phosphates, phosphites and phosphines; and the triphenyl, tritolyl (or tricresyl) diphenyl cresyl, and trixylyl phosphates and phospln'tes, although compounds such as tii(4-ethylphenyl), tri(4-tertiarybutylphenyl), tri(2-naphthyl), tri- (4-isopropyl-1-n-aphthyl), tribenzyl, diisoamyl cyclohexyl dibutyl phenyl, Z-naphthyl diphenyl, dicresyl propyl, and methyl dibutyl phosphates and phosphites are also suitably used. Commercial tzicresyl phosphate, commercial trimethyl phosphate and commercial tributyl phosphate are particularly useful as cheap, readily available and effective compounds.

EXAMPLE X The effectiveness of substituting a phosphorus compound for part of the sulfilr in the compositions of the invention was demonstrated in tests conducted exactly the same as, and as an extension of, the tests described above in Example VI. To additional, separate portions of the Gasoline No. 1 of that example, containing 1.0 theory of boron but only 0.4 theory of sulfur, were added 0.2 and 1.0 theory of phosphorus in the form of tritolyl phosphate (i.e., tricresyl phosphate), to make, respectively, Gasoline No. 4 and Gasoline No. 5. Table X gives the results obtained, the results on Gasoline No. 1 being also again shown for comparison:

The effectiveness of substituting a phosphorus compound for part of the sulfur in the compositions of the invention was also demonstrated in tests conducted exactly the same as, and as an extension of, the tests described above in Example VH. To additional separate portions of the Composition 2 of that example, containing 1.0 theory of the boric acid polyester and 1.0 theory of sulfur, were added 0.2 theory and 1.0 theory of trimethyl phosphate. The resulting compositions gave deposits with reduced fusing and increased powderiness in the same way as did the compositions with sulfur added to raise the sulfur concentration to 3.0 and 5.0 theories.

EXAMPLE XII Additional suitable compositions in accordance with the invention are as follows.

(1) Automotive gasoline hydrocarbons (desulfurized),

containing:

(a) Tetraethyl lead; 3.0 mL/imperial gallon (b) Ethyl ester of the mono-acid cyclic diester of boric acid and 2-methyl-2,4-pentanedio1; 1.0 theory Butylthiophene; 3.0 theory (d) No halohydrocarbon compound i2 (2) Treated automotive gasoline hydrocarbons containing:

(a) Sulfur in the form of a mixture of the naturally occurring sulfur compounds, dimethyl, diethyl and dibutyl disulfides, thiophene and methyl thiophene; 2.0 theory (b) Tetraethyl lead; 3.5 mL/irnperial gallon (c) Phenylboronic acid anhydride; 0.5 theory (d) No halohydrocarbon compound (3) Automotive gasoline hydrocarbons containing:

(a) Sulfur in the form of naturally occurring sulfur compounds, 0.2 theory (b) Tetraethyl lead, 1.2 mL/imperial gallon (c) Triisobutyl borate; 1.2 theory (d) Thiophene; 2.0 theory (e) No halohydrocarbon compound (4) Gasoline antiknock additive containing:

(a) Tetraethyl lead (b) Phenylboronic acid anhydride; 1.0 theory (c) Butylthiophene; 1.5 theory (d) No halohydrocarbon compound.

The use of boronic and borinic acids of the general formula R B(OH) as described hereinbefore, is illustrated by the following examples:

EXAMPLE XIII To a liquid fuel comprising a mixture of unleaded 73 octane aviation gasoline and normal heptane, which fuel possessed a C.F.R. Motor Method (F-2) octane number of 50, was added 1.5 milliliters of tetraethyl lead per imperial gallon, but no halogen scavenger compound. The resulting fuel is referred to in this example as the base fuel.

0.66 theory of phenyl boronic acid, based on the tetraethyl lead content, was added to one portion of the base fuel.

A conventional scavenging agent, viz. 0.5 theory of ethylene dibromide and 1.0 theory of ethylene dichloride, based upon the tetraethyl lead content, was added to a second portion of the base fuel.

The base fuel containing the conventional scavenging agent and the base fuel containing the phenyl boronic acid were separately tested in a Petter engine (the Word Potter is a registered trademark) under cyclic conditions for a period of 9 0 hours with the ignition set at a position such that no knockin occurred.

At the conclusion of each test, the Petter engine was dismantled and the total quantity of deposits formed in the combustion chamber was determined. It was. found that the weight ratio of the deposits which were formed by the base fuel containing the conventional scavenging agent to the deposits which were formed by the base fuel containing the phenyl boronic acid was 2.6:1.

EXAMPLE XIV A catalytically-cracked gasoline derived from Middle East sources which contained 1.0 milliliter of tetraethyl lead per imperial gallon but no halogen scavenger compound was employed in this example as the base fuel.

1.0 theory of ethylene dibromide, based on the lead content, was added to one portion of the base fuel, and 0.1, 0.5 and 1.0 theory of phenyl boronic acid, respectively, were added to three further portions of the base fuel.

All four samples were separately tested in a Petter engine under cyclic conditions for a period of hours, with the ignition set at a position such that no knocking occurred.

The deposits formed in the combustion chamber at the end of each test were removed and weighed. The results are set out in Table XI:

EXAMPLE XV A catalytically-cracked gasoline derived from Middle East sources which contained 1.0 milliliter of tetraethyl lead per imperial gallon but no halogen scavenger compound and which had an octane number (Fl) of 95 was employed in this example as the base fuel.

1.0 theory of phenyl boronic acid, based upon the lead content, was added to one portion of the base fuel, and 1.0 theory of ethylene dibromide was added to a further portion of the base fuel.

Both portions were separately tested in a Petter engine under cyclic conditions for a period of 90 hours. At the end of this period, it was found that the octane requirernent increment of the engine at degrees spark adyance in the case of the base fuel containing the ethylene dibroinide was 3.5; whereas the octane requirement increment of the engine at 15 degrees spark advance in the case of the base fuel containing the phenyl boronic acid was only 1.

EXAMPLE XVI A commercial gasoline, consisting of 80% catalyticallycracked and 15% straight run gasoline, both derived from Middle East sources, and 5% butane, and containing 1.5 ml. of tetraethyl lead per imperial gallon but no halogen scavenger compound was used as the base fuel. The octane number of this fuel was 94 (Fl).

To one portion of the base fuel was added 0.5 theory of ethylene dibromide and 1.0 theory of ethylene dichloride.

To another portion of the base fuel phenyl boronic acid anhydride was added in a proportion of 1 theory with respect to the lead content of the fuel.

The fuels were used in two motor cars of the type Ford Consul which were driven under normal conditions for 3500 miles, after which the engines were inspected.

It was found that the cylinders of the engine in which the fuel with the conventional scavenger had been used contained 11.6 g. of deposits. The engine in which the fuel containing the phenyl boronic acid anhydride scavenger had been used contained only 3.7 g. of cylinder deposits.

Whereas the sparking plug ignition timing of the engine which was run on the boron-containing fuel did not require any adjustment to prevent knocking of the engine during the test, the spark plug ignition timing of the engine which was run on the fuel with the conventional scavenger had to be retarded 7 during the test to prevent knocking of the engine. This indicates that the octane requirement of the engine which had been run on the fuel with the conventional scavenger had considerably increased during the test, whereas there was no change in the octane requirement of the engine which had been run on the fuel with the boron-containing scavenger according to the invention.

EXAMPLE XVII This example demonstrates the importance of the presence of sulfur or phosphorus compounds in obtaining the best scavenging effect with the boron-containing additives according to the invention.

The test was carried out with a Ford Consul engine,

14 which was run under high'duty cycling conditions on gasoline containing 3.5 ml. of tetraethyl lead per imperial gallon but no halogen scavenger compound, 1.0 theory of phenyl boronic acid anhydride and varying proportions of sulfur and phosphorus compounds. The sulfur was added in the form of naturally occurring sulfur compounds by blending the base fuel with a fraction of a Middle East crude oil with a high sulfur content and the phosphorus in the form of tritolyl phosphate. The fuels were compared by measuring the number of spark plug failures due to bridging of the spark plug gap, during a running period of hours, and the results are given in Table XII.

Table XII Proportion Number (in theories) 0iof plug Gasoline No. failures per 100 hours Sulfur Phosphorus EXAMPLE XVIII This example demonstrates the reduction in enginewear which can be attained by replacing the conventional halide scavengers by the boron-containing compounds according to the invention.

The test was carried out with a single cylinder Petter engine (Petter is a registered trademark) which was run under constant load at 1100 rpm. The piston was fitted with a top-ring which had been made radioactive. The wear rate per hour was measured by counting increase in the number of the radioactive pulses per second from the abraded metal which was suspended in the lubricating oil. The lubricating oil used was a solvent refined lubricating oil derived from a Venezuelan crude oil.

The base fuel was a catalytically cracked gasoline of Middle East origin, containing 0.11% of sulfur and 1.8 ml. of tetraethyl lead per imperial gallon but containing no halogen scavenger compound. To one part of this base fuel, 1 theory of phenyl boronic acid anhydride was added (Fuel A); to another part of the base fuel 0.5 theory of ethylene dibromide and 1.0 theory of ethylene dichloride were added (Fuel B). The results of the tests on these two fuels are given below in Table XIII.

EXAMPLE XIX This example demonstrates the efiect of the additives according to the invention upon the extent of lacquer formation on the pistons of the engine. The engine was a Fetter side valve engine (Petter is a registered trademark) which was run on a catalytically cracked gasoline, derived from Middle East sources, containing varying proportions of tetraethyl lead and scavenging agents. The lacquer formation on the piston skirt was rated visually on a scale, ranging from 10 to l in which 10 represents total absence of any lacquer and 1 very heavy lacquering, covering the Whole piston skirt.

From Table XIV, which shows the results of these tests, it will be clear that the lacquer formation on the piston skirt is much less when using as scavenger phenyl boronic acid anhydride than when using a conventional halide scavenger:

T able XIV Milliliters Deposit Piston Scavenger TEL per weight skirt Imp. gallon (gm) rating 1 theory ethylene dichloride+0.5

theory ethylene dibromide 1. 6. 6 5.

0 2.0 9.85 5 1.0 theory phenyl boronio acid anhydride 1. 0 2. 5 8. 5 D 2.0 3. 34 9 ry phenyl borom'c acid anhydride 1.0 1. 9 8. 5 D0 2.0 8.5

1 Not determined.

EXAMPLE XX Benefits similar to those obtained in Examples I through VlI are obtained with a leaded gasoline containing 1.5 milliliters of tetraethyl lead per imperial gallon, no halogen scavenger compound, and various amounts, e.g., 0.2 1.2, and 0.8 theories, of bis(di-2-ethylhexylammonium)phenyl boronate.

In addition to the additives essential to the invention as described above, the compositions of the invention can, and ordinarily will contain other additives generally used in commercial antiknock concentrates and gasoline compositions. Most importantly the compositions will usually contain one or more oxidation inhibitors such as 2,6-ditertiarybutyl-4-methylphenol, 2,4-methyl-6-tertiarybutylphenol, 2,6ditertiarybutylphenol, N,N-disecondarybutylparaphenylene-diamine or other well known oxidation inhibitors. Also there will often be advantageously present corrosion inhibitors, anti-icing agents, metal deactivators, and the like. i

application is a continuation-impart of our copending application, Serial No. 604,080, filed August 15, 1956, and now abandoned.

We hereby claim as our invention:

1. An essentially halohydrocarbon-free gasoline composition consisting essentially of a major amount of hydrocarbons boiling in the gasoline boiling range, a minor antiknock amount of an organo-lead an-tiknock agent, and, per gram atom of lead in the lead antiknock agent present, from about 0.067 to about 3.3 gram atoms of combined boron and from about 0.5 to about 15 gram atoms of combined sulfur.

2. An essentially halohydrocarbon-free gasoline composition consisting essentially of a major amount of hydrocarbons boiling within the gasoline boiling range, a minor antiknock amount of an organo-lead antiknock agent, and, per gram of lead in the lead antiknock agent present, from about 0.33 to about 2.0 gram atoms of organically combined boron, and from about 0.5 to about 15 gram atoms of organically-combined sulfur.

3. An essentially halohydrocarbon-free gasoline composition consisting essentially of a major amount of hydrocarbons boiling within the gasoline boiling range, a minor antiknock amount of a tetraalkyl lead antiknock agent, and, per gram of lead in the lead antiknock agent present, from about 0.33 to about 2.0 gram atoms of boron in the form of a gasoline-soluble organic boron compound containing at least about 1% by weight boron, and from about 0.5 to about 15 gram atoms of organically-combined sulfur.

4. An essentially halohydrocarbon-free gasoline com position consisting essentially of a major amount of hydrocarbons boiling within the gasoline boiling range, a minor antiknock amount of a tetraal-kyl lead antiknock agent, and, per gram of lead in the lead antiknook agent present, from about 0.33 to about 2.0 gram atoms of boron in the form of a gasoline-soluble organic boron compound containing at least about 2% by weight boron and no elements other than boron, oxygen, carbon and hydrogen, and from about 0.5 to about 15 gram atoms of organically-combined sulfur.

5. An essentially halohydrocar'oon-free gasoline composition consisting essentially of a major amount of hydrocarbons boiling within the gasoline boiling range, a minor antiknock amount of a tetraalkyl lead antiknock agent, and, per gram of lead in the lead anti-knock agent present, from about 0.33 to about 1.0 gram atom of boron in the form of a gasoline-soluble ester of an oxyacid of boron containing at least about 5% by Weight boron and no elements other than boron, oxygen, carbon and hydrogen, and from about 0.5 to about 15 gram atoms of organically-combined sulfur.

6. An essentially halohydrocarbon-free gasoline composition consisting essentially of a major amount of hydrocarbons boiling within the gasoline boiling range, a minor antiknock amount of a tetraal'kyl lead antiknock agent, and, per gram of lead in the lead antiknock agent present, from about 0.33 to about 1.0 gram atom of boron in the form of a gasoline-soluble alkanediol ester of boric acid containing at least about 5% by Weight boron and no elements other than boron, oxygen, carbon and hydrogen, and from about 0.5 to about 15 gram atoms of organically-combined sulfur.

7. An essentially halohydro-carbon-free gasoline composition consisting essentially of a major amount of hydrocarbons boiling Within the gasoline boiling range, a minor antiknock amount of an organo-lead antiknock agent, and, per gram of lead in the lead antiknock agent present, from about 0.067 to about 3.3 gram atoms of combined boron, from about 0.25 to about 15 gram atoms of combined sulfur and from about 0.04 to about 1.0 gram atom of combined phosphorus.

8. An essentially halohydrocarbon-free gasoline composition consisting essentially of a major amount of hydrocarbons boiling within the gasoline boiling range, a minor antiknock amount of a tetraalkyl lead anti'knock agent, and, per gram of lead in the lead antiknock agent present, from about 0.33 to about 2.0 gram atoms of boron in the form of a gasoline-soluble organic boron compound containing at least about 2% by weight boron and no elements other than boron, oxygen, carbon and hydrogen, from about 0.25 to about 15 gram atoms of organically-combined sulfur, and from about 0.04 to about 1.0 gram atom of phosphorus in the form of a gasoline soluble organic phosphorus compound containing no elements other than phosphorus, oxygen, sulfur carbon and hydrogen.

9. An essentially halohydrocarbon-free antiknoek concentrate suitable for addition to gasoline consisting essentially of an organo-lead antiknock agent, and, per gram of lead in the lead antiknock agent present, from about 0.067 to about 3.3 gram atoms of combined boron and from about 0.5 to about 15 gram atoms of combined sulfur.

10. An essentially halohydrocarbon-free antiknock concentrate suitable for addition to gasoline consisting essentially of a tetraalkyl lead antilmock agent, and, per gram of lead in the lead antiknock agent present, from about 0.33 to about 2.0 gram atoms of boron in the form of a gasoline-soluble organic boron compound containing at least about 2% by weight boron and no elements other than boron, oxygen, carbon and hydrogen, and fromv about 0.5 to about 15 gram atoms of organically combined sulfur.

1'1. Gasoline containing a minor anti-detonant amount of a tetraalkyl lead anti-deton-an-t, from about 0.5 to about 6.0 theories of naturally occurring sulfur in an oil-soluble organic form, and, as the sole scavenger for said anti-detonant, from about 0.1 to about 3.0 theories of an oil-soluble organic boron compound selected from the group consisting of those having the formula and anhydrides and ammonium salts thereof, wherein R is an aryl radical containing no more than 14 carbon atoms and attached to the boron atom through an aryl ring carbon atom, and m and n are both Whole numbers from 1 to 2, inclusive, and the sum of m and n being equal to 3, a theory of sulfur being that amount stoichiometrically required to convert all the lead of the lead anti-detonant present to PbSO and a theory of the boron compound being that amount stiochiometrically required to convert all the lead of the lead anti-detonant present to Pb (BO l2. Gasoline containing a minor anti-detonant amount of tetraalkyl lead anti-detonant, a minor amout of naturally occurring sulfur in an oil-soluble organic form, an amount of an oil-soluble organic hydrocarbyl triester of an oxyacid of phosphorus sufiicient such that the total sulfur and phosphorus equivalent concentration is from about 0.5 to 6.0 theories, and, as the sole scavenger for said anti-detonan-t, from about 0.1 to about 3.0 theories of an oil-soluble organic boron compound selected from the group consisting of those having the formula and anhydrides and ammonium salts thereof, wherein R is a cyclic organic radical containing no more than 14 carbon atoms and attached to the boron atom through an aryl ring carbon atom, and m' and n are both whole numbers from 1 to 2, inclusive, the sum of m and n being equal to 3, a theory of sulfur being that amount stoichiometrically required to convert all of the lead of the lead anti-detonant present to PbSO a theory of the phosphorus compound being that amount stoic'hiometrically required to convert all the lead of the lead antidetonate present to P b (PO and a theory of the boron compound being that amount stoichiometn'cally required to convert all of the lead of the anti-detonant present to Pb (BO 13. Gasoline containing from about 0.5 to about 5 milliliters of tetraethyl lead per imperial gallon, a minor amount of naturally occurring sulfur in an oil-soluble organic form, an amount of tritolyl phosphate sufficient such that the total sulfur and phosphorus equivalent concentration is from about 1.0 to about 2.0 theories, and

as. the sole scavenger for said tetraethyl lead, an amount of phenyl boronic acid from about 0.5 to about 1.5 theories, a theory of sulfur being that amount stoichio metrically required to convert all of the lead of the lead anti-detonant present to PbSO a theory of the phosphorus compound being that amount stoichiometrically required to convert all the lead of the lead anti-detonant present to Pb (PO and a theory of the boron 601111- pound being that amount stoichiometrically required to convert all of the lead of the lead anti-detonant present References Cited in the file of this patent UNITED STATES PATENTS 1,913,970 Albers June 13, 1933 2,151,432 Lyons et al. Mar. 21, 1939 2,557,019 Morris et a1 June 12,1951 2,710,251 Darling June 7, 1955 2,720,448 Arimoto Oct. 11, 1955 2,720,449 Arimoto Oct. 11, 1955 2,794,719 Bartleson June 4, 1957 2,809,617 Bartleson et al. Oct. 15, 1957 2,839,564 Garner June 17, 1958 2,843,465 Yust et a1. July 15, 1958 2,844,447 Darling July 22, 1958 FOREIGN PATENTS 683,405 Great Britain Nov. 26, 1952 OTHER REFERENCES Ind. and Eng. Chem., vol. 43, No. 3, March 1951, Antiknock Antagonist, by Livingston, pp. 663-670.

Reprint from 1nd. and Eng. Chem., vol 43, December 1951, Gasoline Combustion-Effect of Boron and Silicon Compounds, by Hughes et al., pp. 2841-2844.

Chemical Abstracts, July 10, 1954, vol. 48, No. 13, page 7885(g).

ASTM Standards on Petroleum Products and Lubricants, November 1954, ASTM-D439-54T, pp. 184 and 185.

Chem. Refining of Petroleum, by Kalichevsky, 1933, The Chem. Cat. Co. 1110., page 28.

Claims

1. AN ESSENTIALLY HALOHYDROCARBON-FREE GASOLINE COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR AMOUNT OF HYDROCARBONS BOILING IN THE GASOLINE BOILING RANGE, A MINOR ANTIKNOCK AMOUNT OF AN ORGANO-LEAD ANTIKNOCK AGENT AND, PER GRAM ATOMS OF LEAD IN THE LEAD ANTIKNOCK AGENT PRESENT, FROM ABOUT 0.067 TO ABOUT 3.3 GRAM ATOMS OF COMBINED BORON AND FROM ABOUT 0.5 TO ABOUT 15 GRAM ATOMS OF COMBINED SULFUR.