Method for preparing omega-nitroxy-1-alkanol

Abstract

The invention relates to a method for preparing omega-nitrooxy-C3-10 alkane-1-alcohol and a preparation method of the omega-nitrooxy-C3-10 alkane-1-alcohol.

Description

[0001] This application is a divisional application of Chinese patent application 201980059429.9 (PCT / EP2019 / 074068) with an application date of September 10, 2019. Technical Field

[0002] The present invention relates to a method for preparing ω-nitrooxy-C 3-10 A safe and effective method for the preparation of alkan-1-ols. Background Art

[0003] Global temperatures are rising, a process known as global warming or climate change. One of the primary focuses of mitigating this warming effect is reducing the amount of greenhouse gases emitted into the atmosphere. Greenhouse gases are emitted from several different natural and anthropogenic sources; however, the two sources with the greatest impact are agriculture and the fossil fuel industry. In agriculture, ruminants, particularly cattle, are the primary contributors to biogenic methane formation, and it is estimated that preventing methane formation from ruminants would nearly stabilize atmospheric methane concentrations. 3-Nitrooxypropanol (3-NOP, also known as 3-nitrooxy-propan-1-ol or 1,3-propanediol mononitrate) has been reported to be highly effective in reducing methane formation in ruminants without adversely affecting microbial fermentation in the host animal (WO-2012 / 084629).

[0004] Mononitration of polyols is generally poorly selective and rapidly leads to the formation of dinitrated or polynitrated alcohols due to poorly controlled kinetics. Furthermore, the same reaction on short-chain alkane diols can easily induce strong decomposition reactions.

[0005] Thus, WO-2012 / 084629 discloses a process for preparing 3-nitrooxypropanol by reacting 3-bromopropanol with silver nitrate in acetonitrile, but this process is not economical in industrial-scale production.

[0006] Zikas et al. (Bioorganic & Medicinal Chemistry, 13 (2005) 6485-6492) disclose the mononitration of alkanediols with acetyl nitrate (produced from nitric acid, acetic acid, and acetic anhydride) in the presence of ethyl acetate at room temperature. In addition to the need for an organic solvent, another disadvantage of this method is the use of acetyl nitrate, which, although an excellent nitrating agent, is also explosive and therefore unsuitable for industrial-scale production.

[0007] WO-2004043898 discloses the batchwise mononitration of alkane diols with stabilized nitric acid in a water-immiscible chlorinated organic solvent at a reaction temperature below room temperature (RT), for example preferably equal to or below 0 °C. The stabilized nitric acid consists of fuming nitric acid diluted in water to a concentration of about 83 to 85 wt% and is substantially free of nitrous acid and nitrogen oxides. The weight ratio of the "stabilized" nitric acid to the alkane diol is from about 10:1 to about 15:1.

[0008] In addition to using chlorinated solvents that are highly undesirable in chemical production, a significant drawback of this method is the need for a high acid equivalent, which results in a high salt load. Moreover, this method uses a non-commercial nitric acid dilution. Also, the reaction requires a low temperature (i.e., <RT) to control selectivity and avoid thermal runaway or even explosion.

[0009] Therefore, there is an urgent need to develop an efficient, economical, and safe industrial method for the direct nitration of α,ω-C 3-10 alkane diols, such as especially 1,3-propanediol, which can be carried out batchwise and in the absence of organic solvents, requires a small amount of nitric acid equivalent, and is easy to scale up. SUMMARY OF THE INVENTION

[0010] Surprisingly and contrary to the common general knowledge in the art, it has now been found that ω-nitrooxy C 3-10 alkane-1-ols, such as especially 3-nitrooxypropanol, can also be obtained in high yield while maintaining the stability of the reaction in a batchwise "solvent-free" one-pot process at a high temperature using much less nitric acid equivalent than reported in the literature.

[0011] Therefore, the present invention relates to a method for preparing ω-nitrooxy C 3-10 alkane-1-ols, the method comprising nitrating an α,ω-C 3-10 alkane diol with a nitrating agent, characterized in that the nitrating agent is a mixture consisting of 50 to 75 wt% aqueous nitric acid, and wherein the nitric acid is used in an amount selected within the range of 3 to 8 molar equivalents based on the α,ω-C 3-10 alkane diol, and wherein the nitration is carried out at a temperature selected within the range of 25 - 100 °C (nitration temperature).

[0012] As used herein, the term "α,ω-C 3-10 alkane diol" refers to a straight-chain α,ω-alkane diol having 3 to 10 carbon atoms, such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol. In all embodiments according to the present invention, 1,3-propanediol is particularly preferred.

[0013] The term "ω-nitrooxy C 3-10 By "alkan-1-ol" is meant a linear ω-nitrooxyalkane-1-ol having 3 to 10 carbon atoms, for example 3-nitrooxypropan-1-ol (also known as 3-nitrooxypropanol), 4-nitrooxybutan-1-ol, 5-nitrooxypentan-1-ol, 6-nitrooxyhexan-1-ol, 7-nitrooxyheptan-1-ol, 8-nitrooxyoctane-1-ol, 9-nitrooxynonan-1-ol and 10-nitrooxydecan-1-ol. Particularly preferred in all embodiments according to the invention is 3-nitrooxypropanol.

[0014] In all embodiments of the present invention, the α,ω-C 3-10 Alkanediol, such as in particular 1,3-propylene glycol, is used in an amount of preferably 3 to 6 molar equivalents, more preferably 3.5 to 5 molar equivalents, more preferably 3.5 to 4.5 molar equivalents, most preferably 3.5 to 4 molar equivalents of nitric acid.

[0015] In all embodiments of the present invention, the concentration of nitric acid in the water is preferably selected in the range of 60 to 72% by weight, even more preferably in the range of 62 to 68% by weight. Such nitric acid is readily commercially available (e.g., from Lonza or Yara). Alternatively, regenerated nitric acid may be used.

[0016] As is known, in all embodiments of the present invention, nitric acid is used as the sole nitrating agent, ie nitric acid is used in the absence of any sulfuric acid or reagents leading to the formation of activated nitrates (eg acetyl nitrates), such as acetic anhydride.

[0017] In an advantageous embodiment, the reaction is carried out in the presence of an agent capable of removing nitrous acid and nitrogen oxides (i.e. in the presence of a suitable nitrite trap), such as in particular urea and / or aminosulfonic acid, most preferably in the presence of urea.

[0018] In all embodiments of the present invention, the α,ω-C 3-10 The amount of alkanediol, for example, the amount of the agent capable of removing nitrous acid and nitrogen oxides (i.e., nitrite trap) is preferably selected in the range of 0.1 to 0.7 molar equivalents, preferably in the range of 0.2 to 0.5 molar equivalents, most preferably in the range of 0.2 to 0.4 molar equivalents, based in particular on the amount of 1,3-propanediol.

[0019] Furthermore, in all embodiments of the present invention, the nitration is preferably carried out in the absence (ie without addition) of any organic solvent, but only in water, i.e., the nitration is carried out in a mixture consisting essentially of nitric acid, water, α,ω-C 3-10 The reaction mixture is carried out in a reaction mixture consisting of an alkane diol and an optional nitrite scavenger.

[0020] As used herein, the term "organic solvent" is well known to those skilled in the art and refers to a carbon-based solvent that can dissolve other substances and is generally liquid at room temperature. Typical organic solvents include aliphatic chain compounds such as hexane, halogenated hydrocarbons such as dichloromethane, esters such as ethyl acetate, ethers such as diethyl ether, aromatic hydrocarbons such as toluene or xylene, alcohols such as methanol or ethanol, and ketones such as acetone, but are not limited thereto.

[0021] In a particularly advantageous embodiment, the present invention relates to a method for preparing ω-nitrooxy C 3-10 A process for preparing an alkane-1-ol, said process comprising preparing a alkane-1-ol by substantially preparing the alkane-1-ol by a process comprising preparing the ... 3-10 The reaction mixture consisting of an alkanediol and a nitrite scavenger is nitrated with a nitrating agent, characterized in that the nitrating agent is a mixture consisting of a 50 to 75 weight % nitric acid aqueous solution, wherein the nitric acid is based on α, ω-C 3-10 The alkanediol is used in an amount selected in the range of 3 to 8 mol equivalents, and wherein the nitration is carried out at a temperature selected in the range of 25-100° C. (nitration temperature), with the proviso that all preferences and definitions as given herein also apply to the process.

[0022] Advantageously, in all embodiments of the present invention, the reaction temperature during the nitration (nitration temperature) is in the range of 25-90°C, more preferably in the range of 25-80°C, for example in the range of 30-80°C, even more preferably in the range of 40-75°C, and most preferably in the range of 50-65°C, such as in particular in the range of 55-65°C or selected in the range of 50 to 60°C or 55 to 60°C or even 60 to 65°C.

[0023] In a particularly advantageous embodiment, when based on α,ω-C 3-10 The amount of alkanediol, in particular, when more than 5 molar equivalents (i.e., 5 to 8 molar equivalents) of nitric acid are used based on the amount of 1,3-propylene glycol, the nitration temperature is selected in the range of 25 to 60° C., and when based on α,ω-C 3-10 When the amount of alkanediol, in particular 5 molar equivalents or less of nitric acid (i.e., 3 to 5 molar equivalents) based on the amount of 1,3-propanediol is used, the nitration temperature is selected in the range of 60 to 100° C., preferably 60 to 90° C., and most preferably 60 to 80° C., because these process conditions result in minimization of undesirable by-products (especially dinitration) while still providing good yields, which can achieve economical industrial-scale production.

[0024] α,ω-C 3-10The mononitration of the alkane diol, preferably 1,3-propanediol, is preferably carried out at a reaction time in the range of about 30 to about 300 minutes, preferably about 60 to about 120 minutes.

[0025] The progress of the reaction can be monitored using conventional analytical methods and the optimal reaction time can thus be determined. Therefore, in a preferred embodiment, the present invention relates to a process according to the invention, wherein the reaction is monitored and terminated at a process yield of about 40-65%, preferably at a process yield of about 40% to 55%, most preferably at a process yield of about 40% to 50% or even 45% to 55%, as determined by HPLC or GC, for example by RP-HPLC based on an external standard.

[0026] As is known, the process according to the present invention is designed to be carried out batchwise (discontinuously) in a safe and economical manner. Therefore, in a preferred embodiment, the present invention relates to a method for preparing ω-nitrooxy C 3-10 A process for the batch nitration of alkane-1-ols.

[0027] In a particularly advantageous embodiment, the process according to the invention with all definitions and preferences as given herein is process (I) comprising the following consecutive steps:

[0028] i. providing a nitrating agent (e.g., by loading the reactor vessel with a nitric acid water mixture), and then

[0029] ii. adding a reagent capable of removing nitrous acid and nitrogen oxides (ie, a nitrite trapping agent) and stirring the resulting reaction mixture, preferably for 10 to 60 minutes, more preferably 15 to 45 minutes, and then

[0030] iii. Add α,ω-C 3-10 Alkanediol, preferably 1,3-propylene glycol (actual nitration reaction).

[0031] In a particularly advantageous embodiment, the process of the invention is process (II) as process (I) comprising the successive steps (i) to (iii), wherein the subsequent step is

[0032] iv. quenching the reaction mixture obtained in (iii) with water or a base to obtain a mixture containing ω-nitrooxy group C 3-10 An aqueous reaction mixture of an alkane-1-ol, preferably 3-nitrooxypropanol.

[0033] Optionally, the aqueous reaction mixture obtained in (iv) may be further neutralized with a suitable base, in particular in case of quenching with water (ie the process comprises a subsequent neutralization step (v)).

[0034] In all embodiments of the present invention, suitable bases include, but are not limited to, alkali metal or alkaline earth metal bases, such as alkali metal or alkaline earth metal hydroxides or carbonates, and amines.

[0035] Preferably, in all embodiments of the present invention, the base used in step (iv) and the optional neutralization step (v) is selected from NaOH, KOH, Ca (OH) 2 or ammonia, more preferably an aqueous solution thereof is used. Most preferably, in all embodiments of the present invention, the base is aqueous NaOH or ammonia (NH 4 OH).

[0036] In the case of quenching with water, process (II) preferably comprises a neutralization step (v).

[0037] In another preferred embodiment, the process according to the present invention further comprises an extraction step (vi).

[0038] The temperature in step (i) and the starting temperature in step (ii) may already be the nitration temperature. However, it is preferred that the temperature in step (i) and the starting temperature in step (ii) are selected in the range of 18-30°C, for example at ambient temperature (usually about 20-22°C), and that the α,ω-C 3-10 Before the addition of the alkanediol, preferably 1,3-propanediol (ie before step (iii)), the reaction mixture obtained in (ii) is heated to the desired nitration temperature with all preferences and definitions as given herein.

[0039] In another advantageous embodiment, the quenching of the reaction is carried out with cold water, for example with water having a temperature selected in the range of 0 to 20° C., more preferably in the range of 5 to 15° C., or with an inorganic base selected in the range of (-20) to 15° C., more preferably in the range of (-10) to 10° C., such as in particular aqueous NaOH, KOH, Ca(OH) 2 or NH 4 OH.

[0040] In a particularly advantageous embodiment, the ω-nitrooxy group C 3-10 The pH of the aqueous reaction mixture of alkane-1-ols, such as in particular 3-nitrooxypropanol, is adjusted to a pH of 8-12, more preferably to a pH of 9-11, most preferably with aqueous sodium hydroxide (NaOH), potassium hydroxide (KOH) or ammonia (NH4OH).

[0041] Preferably, in all embodiments of the present invention, during the workup, the ω-nitrooxyalkane-1-ol, more preferably 3-nitrooxypropanol, is separated from the residual starting material (i.e., α,ω-C 3-10 Alkanediol, preferably 1,3-propylene glycol) and by-products (i.e., α,ω-C 3-10Alkanediol dinitrate, preferably 1,3-propylene glycol dinitrate) is separated.

[0042] Therefore, the present invention also relates to process (III), which is process (I) or (II), comprising an additional extraction step (vi) after step (iii), step (iv) or step (v).

[0043] Particularly preferred in all embodiments of the present invention is process (IV) comprising a selective extraction step (vi) after a quenching step (iv) and a neutralization step (v).

[0044] Prior to the selective extraction, it is preferred to 3-10 The pH of the aqueous mixture of alkane-1-ols, such as in particular 3-nitrooxypropanol, is adjusted to a pH of 8-12, more preferably to a pH of 9 to 11, most preferably with aqueous sodium hydroxide (NaOH), potassium hydroxide (KOH) or ammonia (NH4OH).

[0045] The selective extraction according to the present invention comprises obtaining in step (iii), (iv) or (v) the ω-nitrooxy C 3-10 The aqueous reaction mixture of alkane-1-ol, preferably 3-nitrooxypropanol, is first treated with a non-polar solvent, such as preferably an aliphatic or aromatic hydrocarbon solvent, more preferably an aromatic solvent such as xylene or toluene, most preferably toluene (to remove impurities / by-products, such as dinitrated α,ω-C 3-10 alkanediols) followed by extraction with an ethereal solvent (e.g. a cyclic ether, such as tetrahydrofuran or dioxane or an alkyl ether, such as diethyl ether, dibutyl ether, diisobutyl ether or methyl tert-butyl ether), such as in particular methyl tert-butyl ether (MtBE) (to extract the ω-nitrooxy C 3-10 Extraction with an alkane-1-ol, such as, in particular, 3-nitrooxypropanol).

[0046] Furthermore, the obtained ether phase is preferably washed with water to ensure complete removal of α,ω-C 3-10 After evaporation of the ether solvent (optionally after a drying step, for example with MgSO 4 ), the pure ω-nitrooxy C 3-10 Alkan-1-ols, such as in particular pure 3-nitrooxypropanol. Even more preferably, the non-polar solvent used in the selective extraction, such as in particular a hydrocarbon, even more in particular an aromatic hydrocarbon solvent phase, is re-extracted with an aqueous solvent, such as an aqueous solution obtained by washing the ether phase, to further increase the ω-nitrooxy C 3-10 Yield of alkane-1-ols.

[0047] In principle, the reaction of the process according to the invention can be carried out in any reactor suitable for the respective reaction type. Without limiting the generality, the following are mentioned by way of example: suspension reactors, stirred tanks, stirred tank cascades, tubular reactors, tubular reactors comprising mixing elements such as static mixers, shell reactors, shell-and-tube reactors, reactive distillation columns.

[0048] As mentioned above, for economic reasons, the aqueous reaction mixture obtained in step (iv) or (v) can be fed directly to ruminants such as, in particular, cattle.

[0049] Due to the ω-nitrooxy 3-10 The aqueous solution of alkane-1-ol, preferably 3-nitrooxypropanol, is still novel and the present invention also relates to the aqueous solution obtainable from step (iv) or (v) above and its use for supplementing ruminants, such as in particular cattle, to reduce methane formation in said ruminants. Such aqueous solutions are characterized by high stability, low toxicity and increased cost efficiency, since there is no need to separate the ω-nitrooxy C before supplementing the ruminants. 3-10 Alkan-1-ol.

[0050] In a particularly advantageous embodiment, the aqueous solution (all weight % are based on the total weight of the aqueous solution) consists essentially of:

[0051] (a) 1 to 30 wt%, preferably 1 to 15 wt%, more preferably 2 to 10 wt%, most preferably 5 to 9 wt% of α,ω-C 3-10 an alkanediol, preferably 1,3-propylene glycol,

[0052] (b) 2.5 to 40% by weight, preferably 5 to 30% by weight, more preferably 5 to 20% by weight, most preferably 7.5 to 20% by weight of ω-nitrooxy groups C 3-10 Alkan-1-ol, preferably 3-nitrooxypropanol,

[0053] (c) 0.1 to 5 wt%, preferably 0.3 to 3 wt%, most preferably 0.5 to 2 wt% of α,ω-dinitrooxy C 3-10 an alkane, preferably 1,3-dinitrooxypropane,

[0054] (d) 0.1 to 10 wt%, preferably 0.1 to 6 wt%, more preferably 0.3 to 4 wt%, most preferably 0.5 to 2 wt% of a nitrite trap, preferably sulfamic acid or urea,

[0055] (e) 5 to 30% by weight, preferably 10 to 25% by weight, most preferably 15 to 20% by weight of a nitrate, preferably sodium nitrate,

[0056] (f) 0.1 to 5 wt%, preferably 0.3 to 3 wt%, most preferably 0.5 to 2 wt% of a base, preferably sodium hydroxide, and

[0057] (g) 30 to 80 wt. %, preferably 40 to 70 wt. %, most preferably 50 to 65 wt. % water.

[0058] Preferred aqueous solutions according to the invention (all weight % are based on the total weight of the aqueous solution) consist essentially of:

[0059] (a) 5 to 10% by weight of 1,3-propylene glycol,

[0060] (b) 5 to 20% by weight of 3-nitrooxypropanol,

[0061] (c) 0.5 to 3% by weight of 1,3-dinitrooxypropane,

[0062] (d) 0.5 to 4% by weight of urea,

[0063] (e) 15 to 20% by weight of sodium nitrate,

[0064] (f) 0.5 to 3% by weight of sodium hydroxide, and

[0065] (g) 50 to 65% by weight of water.

[0066] The most preferred aqueous solution according to the present invention (all weight % are based on the total weight of the aqueous solution) consists essentially of:

[0067] (a) 5 to 9% by weight of 1,3-propylene glycol,

[0068] (b) 5 to 20% by weight of 3-nitrooxypropanol,

[0069] (c) 0.5 to 2% by weight of 1,3-dinitrooxypropane,

[0070] (d) 0.5 to 2% by weight of urea,

[0071] (e) 15 to 20% by weight of sodium nitrate,

[0072] (f) 0.5 to 2% by weight of sodium hydroxide, and

[0073] (g) 50 to 65% by weight of water.

[0074] The term "essentially consisting of" as used in the present invention means that the amounts of components (a) to (g) add up to 100% by weight. However, the presence of small amounts of impurities or additives, for example introduced by the individual raw materials of components (a) to (g), is not excluded.

[0075] The following examples are intended to further illustrate the present invention, but are not intended to limit it. Example

[0076] Example 1: Preparation of 3-nitrooxypropanol (3-NOP)

[0077] A) Formation of nitrate esters

[0078] Throughout the nitration process, nitration is carried out in a double-jacketed reactor that remains open, preferably with a light nitrogen flow above the reaction. Nitric acid (3-14 equivalents based on the 1,3-propylene glycol shown in Table 1) is charged into the reactor and stirred at 20°C for 15 minutes. Urea (0.3 equivalent) is added and stirring is continued for 30 minutes. At the same time, the jacket temperature is set to the reaction temperature (20-90°C). 1,3-propylene glycol (1 equivalent) is then dosed into the acid via a dropping funnel over 15 minutes, and the reaction is stirred for 60-120 minutes. The reaction is then quenched by pouring it into water cooled to 10-15°C to dilute the nitric acid to an amount of ~20%. The quenched reaction solution is slowly adjusted to pH 9-11 with 30% aqueous NaOH. Alternatively, the reaction is quenched by pouring the reaction into 20% aqueous NaOH cooled to (-10)-10°C to obtain an aqueous solution of pH 9-11.

[0079] B) Post-processing (selective extraction)

[0080] The aqueous solution obtained in step A is subsequently extracted with toluene and then with MtBE. The MtBE phase is washed with water and evaporated to dryness to give 3-nitrooxypropanol (1,3-propylene glycol mononitrate) as a colorless to pale yellow oil.

[0081] Table 1

[0082]

[0083] * Deep nitration, the reaction is slightly unstable during the addition of 1,3-propylene glycol

[0084] # The isolated yield was reduced by approximately 1-10% compared to the in-process yield.

[0085] The above synthesis of 3-nitrooxypropanol (PDMN) using the conditions in Table 1, entry 5 (4 equivalents 65% HNO3, 70°C, 60 minutes) with quenching on 20% NaOH gave a 52% yield for a 25 g scale.

[0086] C.) Composition of the neutralized reaction mixture

[0087] (Conditions: Table 1, entry 5, quenched on 20% NaOH)

[0088]

[0089]

[0090] Example 2

[0091] The synthesis of 3-nitrooxypropanol (PDMN) as described above (4 equivalents of 65% HNO3, 60°C, 90 minutes) using 0.3 equivalents of sulfamic acid in place of urea gave an isolated yield of 34%.

[0092] Example 3

[0093] Repeating the above example (4 equivalents of 65% HNO3, 60°C, 90 minutes) using 1,4-butanediol instead of 1,3-propanediol gave 4-nitrooxybutanol in 19% isolated yield.

Claims

1. A method for preparing ω-nitrooxy C 3-10 A method for nitrating an α,ω-C alkane-1-ol with a nitrating agent, optionally in the presence of a nitrite trap 3-10 Alkanediol, characterized in that The nitrating agent is a mixture consisting of 50-75 wt% nitric acid aqueous solution, wherein the nitric acid is based on the α,ω-C 3-10 The alkanediol is used in an amount selected in the range of 3 to 8 molar equivalents, and wherein the nitration is carried out at a temperature selected in the range of 25-100°C, preferably in the range of 25-90°C, most preferably in the range of 25-80°C.

2. The method according to claim 1, characterized in that The ω-nitrooxy group C 3-10 The alkane-1-ol is 3-nitrooxypropanol, and the α,ω-C 3-10 The alkanediol is 1,3-propylene glycol.

3. The method according to claim 1 or 2, wherein the α,ω-C based 3-10 Alkanediol 3 to 6, preferably 3.5 to 5 molar equivalents of nitric acid.

4. The method according to any one of claims 1 to 3, wherein the concentration of the aqueous nitric acid solution is selected in the range of 60 to 72 wt. %, preferably in the range of 62 to 68 wt. %.

5. The method according to any one of claims 1 to 4, wherein the nitrite trapping agent is sulfamic acid and / or urea, most preferably urea.

6. The method according to any one of claims 1 to 5, wherein the α,ω-C 3-10 The amount of the nitrite capture agent is selected from the range of 0.1 to 0.7 molar equivalents, preferably from the range of 0.2 to 0.4 molar equivalents.

7. The process according to any one of claims 1 to 6, wherein the reaction temperature is selected in the range of 40-75°C, more preferably in the range of 50-65°C, most preferably in the range of 55-65°C.

8. The method according to any one of claims 1 to 7, wherein the nitration is carried out for a time in the range of 10 to 300 minutes.

9. The method according to any one of claims 1 to 8, comprising the steps of: i. providing the nitrating agent, then ii. adding the nitrite trapping agent and preferably stirring the obtained reaction mixture for 10 to 60 minutes, more preferably 15 to 45 minutes, and then iii. Add α,ω-C 3-10 Alkanediol, preferably 1,3-propylene glycol and optionally iv. quenching the reaction mixture obtained in (iii) with water or a base to obtain a mixture containing ω-nitrooxy group C 3-10 Aqueous reaction mixtures of alkan-1-ols.

10. The process according to claim 9, wherein the aqueous reaction mixture, optionally after neutralization with a suitable base, is extracted successively first with an aromatic hydrocarbon solvent and then with an ether solvent.

11. The method according to claim 10, wherein the aromatic hydrocarbon solvent is toluene, and the ether solvent is methyl tert-butyl ether.

12. An aqueous reaction mixture obtainable by the process according to any one of claims 1 to 11.

13. The aqueous reaction mixture of claim 12, which is an aqueous solution consisting essentially of: (a) 1 to 30 wt%, preferably 1 to 15 wt%, more preferably 2 to 10 wt%, most preferably 5 to 9 wt% of α,ω-C 3-10 an alkanediol, preferably 1,3-propylene glycol, (b) 2.5 to 40% by weight, preferably 5 to 30% by weight, more preferably 5 to 20% by weight, most preferably 7.5 to 20% by weight of ω-nitrooxy groups C 3-10 Alkan-1-ol, preferably 3-nitrooxypropanol, (c) 0.1 to 5 wt%, preferably 0.3 to 3 wt%, most preferably 0.5 to 2 wt% of α,ω-dinitrooxy C 3-10 an alkane, preferably 1,3-dinitrooxypropane, (d) 0.1 to 10 wt%, preferably 0.1 to 6 wt%, more preferably 0.3 to 4 wt%, most preferably 0.5 to 2 wt% of a nitrite trap, preferably sulfamic acid or urea, (e) 5 to 30% by weight, preferably 10 to 25% by weight, most preferably 15 to 20% by weight of a nitrate, preferably sodium nitrate, (f) 0.1 to 5 wt%, preferably 0.3 to 3 wt%, most preferably 0.5 to 2 wt% of a base, preferably sodium hydroxide, and (g) 30 to 80 wt. %, preferably 40 to 70 wt. %, most preferably 50 to 65 wt. % of water, and, All weight % are based on the total weight of the aqueous solution.

14. Use of the aqueous reaction mixture according to claim 12 or 13 for supplementing ruminants to reduce methane formation in the ruminants.

15. A method of administering the aqueous reaction mixture according to claim 12 or 13 to a ruminant to reduce methane emissions from the ruminant.

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