1-METHYLCYCLOPROPENE GENERATING DEVICE

Abstract

A device for generating 1-methylcyclopropene (1-MCP) using an improved carrier gas flow control system. It also relates to the use of a 1-MCP generating device to inhibit the action of ethylene, which accelerates the ripening process of plants such as fruits, flowers, vegetables, and the like. Furthermore, it relates to a method for treating and storing harvested agricultural products using such a 1-MCP generating device.

Description

DEVICE TO GENERATE ULTRAPURE 1-METHYLCYCLOPROPENE Technical field The present invention relates to a device for generating 1-methylcyclopropene (1-MCP) using an improved carrier gas flow control system. The invention also relates to the use of a 1-MCP generating device to inhibit the action of ethylene, which accelerates the ripening process of plants such as fruits, flowers, vegetables, and the like. Furthermore, the invention encompasses a method for treating and storing harvested agricultural products using said 1-MCP generating device. Background Plant growth and fruit ripening are affected by several factors, including plant hormones that regulate a wide variety of cellular processes. One well-known plant hormone is ethylene, which mediates plant growth by interacting with specific ethylene receptors. Many non-ethylene compounds interact with this receptor: some mimic the action of ethylene, while others prevent ethylene binding and thus counteract its effects. Cyclopropene derivatives such as 1-methylcyclopropene (1-MCP) can bind strongly to ethylene receptors in plants and thereby block the effects of ethylene, resulting in the maintenance of the freshness of plants and flowers or the prevention of fruit ripening. 1-MCP (1-methylcyclopropene) is a volatile gas at standard temperature and pressure that facilitates the treatment of agricultural products in storage. However, it is chemically unstable. 232.906 when not stored at a low temperature (below -100 °C) and may easily experience loss of its chemical properties through dimerization, etc. To address the challenges associated with 1-MCP storage, several solutions have been proposed. WO-00 / 10386 discloses the encapsulation of 1-MCP in cyclodextrins, where the 1-MCP is released upon heating the 1-MCP / cyclodextrin complex. WO-2007 / 058473 provides another solution, disclosing a device for the in-situ chemical generation of 1-MCP. This device stores the 1-MCP precursor and an activating reagent in two separate storage containers, and the 1-MCP is synthesized via a chemical reaction. WO-2012 / 134088 discloses a device, as shown in Figure 1, for generating 1-MCP. The device comprises a first container with tetrabutylammonium fluoride (TBAF) dissolved in DMF, a second container with a solution of t-rans-l-methyl-1-(methanesulfonyloxy)-2-(butyldimethylsilyl)cyclopropane (i.e., the 1-MCP precursor), and a carrier gas. The carrier gas is introduced into the first container to transfer the TBAF solution to the second container with the 1-MCP precursor solution. A chemical reaction in this second container generates 1-MCP, which is then carried by the carrier gas to a third container where it is cleaned before being transported to the outside by the carrier gas. The carrier gas is air from an electric bubble generator for a fish tank with a flow rate of 100 to 200 mL / min. WO-2005 / 080267 describes a process and reactor for the production of chloramine where the flow of reactant gases and carrier gas is controlled by mass flow controllers. WO-2016 / 053201 describes a method and system for producing fins by dehydrogenating vaporized ethanol supplied by a nitrogen flow to a fixed-bed reactor where the nitrogen flow is controlled by a mass flow controller. US-2006 / 0037644 describes a mass flow controller capable of providing a consistently stable supply of a desired flow rate despite upstream or downstream pressure fluctuations relative to the mass flow controller. Technical problem The pump for generating the carrier gas in the 1-MCP generating device disclosed in WO-2012 / 134088 is an electric bubble generator for a fish aquarium and in the field suffers significant variations in flow magnitude that are probably related to changes in ambient temperature, air pressure, humidity and aging of the rubber membrane of the aquarium bubble generator membrane pump. Depending on the size of the 1-MCP generator and the amount of 1-MCP required, the carrier gas flow rate can range from 20 mL / min to 200 mL / min, and these low flow rates are difficult to regulate reliably. When the carrier gas flow rate is too high for a given size of 1-MCP generator, there is a greater likelihood of releasing impurities, such as small amounts of solvent or reaction byproducts, along with the 1-MCP. When the carrier gas flow rate is too low, the 1-MCP generator needs to operate longer to produce enough 1-MCP to treat the produce in the storage area, with greater uncertainty as to whether enough 1-MCP has been released to treat all the produce. An initial attempt to achieve a reproducible and constant carrier gas flow rate with minimal deviation from the desired flow rate utilized a mechanical needle valve. However, this required complex daily calibration of the needle valve to ensure the carrier gas flow rate remained consistent. Therefore, a 1-MCP generating device with a well-controlled, reproducible, and constant carrier gas flow magnitude is required. Technical solution It has recently been observed that a well-controlled, reproducible, and constant carrier gas flow rate can be achieved in a 1-MCP generating device by measuring the carrier gas flow rate with a mass flow sensor and regulating the pump using an electronic flow control circuit. Furthermore, it has also been observed that the performance of the mass flow sensor can be further improved by placing a flow reducer between the pump and the mass flow sensor. Detailed description A mass flow sensor, also known as an inertial flow meter, is a device that measures the mass flow rate of a gas traveling through a tube. Mass flow rate is the mass of gas moving past a fixed point per unit of time. The mass flow sensor does not measure the volume per unit of time (e.g., cubic meters per second) passing through the device; it measures the mass per unit of time (e.g., kilograms per second) flowing through the device. The output of a mass flow sensor mass flow rate, that is, the signal indicating the magnitude of the flow, is normally expressed as SCCM (standard cubic centimeters per minute), a term of flow measurement that indicates cm3 / min at a standard temperature and pressure (i.e., Tn= 0 °C, Pn= 1.01 bar). These are commercially available mass flow sensors, for example, the AWM3000 series supplied by Honeywell. Specific achievements Description of the drawings: Figure 1: 1-MCP Generator from document WO2012 / 134088 (before use) in which container 1 contains the TBAF solution and container 2 contains the 1-MCP precursor solution. Figure 2: 1-MCP generating device according to the present invention wherein a mass flow sensor is used to regulate the magnitude of the carrier gas flow produced by the pump and a flow reducer is present between the pump and the mass flow sensor. Figure 3: 1-MCP generating device according to the present invention further equipped with a heating element in the second container. Figure 4: 1-MCP generating device according to the present invention further equipped with a heating element in containers 1 and 2. Figures 2, 3, and 4 are drawings illustrating the design and operation of a 1-MCP generating device according to an embodiment of the present invention. In the drawings, the same reference numbers denote the same elements of the 1-MCP generating device. Figure 2 is a drawing illustrating an embodiment of a 1-MCP generating device where the magnitude of the carrier gas flow does not deviate by more than 20% from the desired flow magnitude, comprising: a first container (1) comprising an inlet (7), an outlet (8) and a compound containing the fluoride ion of formula (II), Ra Rb—N—Rd F_ (II) Rc where Ra, Rb, Rc and Rd are each independently selected from C1-20 alkyl, phenyl and naphthyl; a second container (2) comprising an inlet (9), an outlet (10) and (5) a 1-MCP precursor of formula (I) R3 where X is halogen, or (alkyl Ci-e)-S ( O) 2O-; R1, R2 and R3 are each independently selected from hydrogen, alkyl Ci_6, phenyl, alkyloxy Ci-g and halogen; a third container (3) comprising an inlet (11), an outlet (12) and a washing solution (6); a pump (P) for supplying a carrier gas that is introduced into the first container (1) to transfer the fluoride ion-containing compound (4) of formula (II) to the second container (2) where said fluoride ion-containing compound (4) of formula (II) reacts with the 1-MCP precursor (5) of formula (I) and the resulting 1-MCP is transferred with the carrier gas to the third container (3) where it is bubbled through the washing solution (6) before the carrier gas with the 1-MCP is released to the outside; characterized in that a mass flow sensor (13) is placed between the pump (P) and the first container (1) to regulate the magnitude of the carrier gas flow and a flow reducer (15) is placed between the pump (P) and the mass flow sensor (13). The mass flow sensor (13) measures the magnitude of the carrier gas flow and provides a flow magnitude signal to the flow control circuit (14) which provides the pump (P) with a modulation signal to regulate the magnitude of the carrier gas flow so that it does not deviate by more than 20% from the desired flow magnitude. It has been observed that the pump (P), especially when using a diaphragm pump, can generate a sound wave in the carrier gas that interferes with the proper functioning of the mass flow sensor (13). This problem can be solved by including a flow reducer (15) between the pump (P) and the mass flow sensor (13). Such a flow reducer (15) can be a short piece of pipe with a reduced diameter. For example, the diameter of the reduced-diameter pipe used as the flow reducer is 1 / 10 of the diameter of the pipe used to connect the pump (P) to the mass flow sensor (13). The flow reducer (15) can also be an orifice disc with a small hole, the diameter of which is between 0.10 mm and 0.25 mm, specifically 0.15 mm. Figure 3 is a drawing illustrating a further embodiment of a 1-MCP generating device comprising, in addition to the device of Figure 3, a heating element (16) for heating the second vessel (2) during the reaction between the 1-MCP precursor (5) and the fluoride ion-containing compound (4). When the 1-MCP generating device is used in a cooled storage facility, the second vessel (2) should be heated to facilitate the reaction between the 1-MCP precursor (5) and the fluoride ion-containing compound (4). Furthermore, carrying out the 1-MCP generating reaction at an elevated temperature that is independent of the ambient temperature provides more reproducible 1-MCP production each time the 1-MCP generating device is used. In particular, the second vessel (2) is heated to a temperature between 30 °C and 50 °C, more specifically between 40 °C and 45 °C.Furthermore, Figure 4 is a drawing illustrating an embodiment of an operating 1-MCP generating device in which the fluoride ion-containing compound (4) and the 1-MCP precursor (5) are mixed in the second container (2). Figure 4 is a drawing illustrating a further embodiment of a 1-MCP generating device comprising, in addition to the device of Figure 4, a heating element (16) for heating the container (1) prior to the reaction between the 1-MCP precursor (5) and the fluoride ion-containing compound (4). The first vessel (1), the second vessel (2), and the third vessel (3) include inlets (7), (9), and (11) and outlets (8), (10), and (12), respectively. The first vessel (1), the second vessel (2), and the third vessel (3) are connected to each other by a tube with its respective inlets and outlets. When the 1-MCP generating device is operating, the carrier gas is supplied through a tube into the first vessel (1) via inlet (7), and outlet (8) of the first vessel (1) is connected to inlet (9) of the second vessel (2) via a tube. Outlet (10) of the second vessel (2) is connected to inlet (11) of the third vessel (3) via a tube, through which the carrier gas transfers the 1-MCP to the outside via outlet (12) of the third vessel (3). In the 1-MCP generating device described in Figures 2 to 4, the first vessel (1) is used to store the fluoride ion-containing compound of formula (II), which is then transferred by carrier gas to the second vessel (2) to be mixed with the 1-MCP precursor of formula (I) to prepare 1-MCP. 1-MCP can also be prepared in this device when the first vessel (1) contains the 1-MCP precursor of formula (I) and the second vessel (2) contains the fluoride ion-containing compound of formula (II). In practice, the carrier gas does not transfer the entire contents of the first vessel (1) to the second vessel (2), and often a small amount remains in the first vessel (1).Because the fluoride ion-containing compound of formula (II) is present in excess with respect to the 1-MCP precursor of formula (I), it has no influence on the yield of 1-MCP that the contents of container (1) are not completely transferred to container (2). General achievements The present invention relates to a 1-methylcyclopropene (1-MCP) generating device where the magnitude of the carrier gas flow does not deviate by more than 20% from the desired flow magnitude, comprising: a first container comprising an inlet, an outlet, and a compound containing the fluoride ion of formula (II) Rb—N—Rd F (II) Rc where Ra, Rb, Rc and Rd are each independently selected from C1-20 alkyl, phenyl and naphthyl; a second container comprising an inlet, an outlet and a 1-MCP precursor of formula (I) R3 where X is halogen, or (alkyl Ci-e)-S ( O) 2O-; R1, R2 and R3 are each independently selected from hydrogen, C1-6 alkyl, phenyl, C1-6 alkyloxy and halogen; a third container comprising an inlet, an outlet, and a washing solution; a pump to supply a carrier gas that is introduced into the first container to transfer the fluoride ion-containing compound of formula (II) to the second container where said fluoride ion-containing compound of formula (II) reacts with the 1-MCP precursor of formula (I) and the resulting 1-MCP is transferred with the carrier gas to the third container where it is bubbled through the washing solution before the carrier gas with the 1-MCP is released to the outside; characterized in that the magnitude of the carrier gas flow is regulated by a mass flow sensor that provides a flow magnitude signal to a flow control circuit that provides the pump with a modulation signal to regulate the magnitude of the carrier gas flow and in that a flow reducer is present between the pump and the mass flow sensor. The pump to supply the carrier gas can be a diaphragm or membrane air pump, a piston pump, a rotary vane pump, or any other device suitable for moving gases. The mass flow sensor, which measures the magnitude of the carrier gas flow, provides a flow magnitude signal to the flow control circuit. This circuit then provides the pump with a modulation signal to regulate the carrier gas flow magnitude so that it does not deviate by more than 20% from the desired flow magnitude. A suitable mass flow sensor for use in the 1-MCP generating device of the present invention is, for example, the AWM3000 series supplied by Honeywell. It has also been observed that the carrier gas flow can be made more constant by introducing a flow restrictor between the pump and the mass flow sensor. Due to the intermittent on / off operation of the pump, the carrier gas flow can fluctuate, which can hinder the mass flow sensor and flow control circuit from maintaining the desired flow magnitude within a 20% deviation. These carrier gas flow fluctuations can be greatly reduced by introducing a flow restrictor between the pump and the mass flow sensor. Such a flow restrictor can be a short piece of pipe with a reduced diameter. For example, the diameter of the reduced-diameter pipe used as a flow restrictor is 1 / 10 the diameter of the pipe used to connect the pump to the mass flow sensor.The flow reducer can also be an orifice disc having a small hole where said hole has a diameter between 0.10 mm and 0.25 mm, in particular 0.15 mm. In one embodiment, the mass flow sensor is placed between the pump and the first vessel. The first vessel, the second vessel, and the third vessel include inlets and outlets that are connected by piping in the desired sequence. 1-Methylcyclopropene (1-MCP) is prepared by reacting a 1-MCP precursor of formula (I) with a fluoride ion-containing compound of formula (II) as depicted in the following reaction scheme: CH3 CH3 Aa ~Si-R2 d3 (I) R Ra NR / J 1-MCP where X is (Ci-6 alkyl)-S(O)2O-; R1, R2 halogen, or R3 are each selected independently from hydrogen, alkyl Cl-6, phenyl, alkyloxy Ci_6 Ra, Rb, and halogen; Rc and Rd are each independently selected from C1-20 alkyl, phenyl, and naphthyl. iodine; As used in the definitions above: Halogen is generic for fluoro, chloro, bromo, and C1-6 alkyl. It defines saturated hydrocarbon radicals of linear and branched chains having 1 to 6 carbon atoms, such as, for example, methyl, ethyl, propyl, butyl, 1-methylethyl, 2-methylpropyl 2-methylbutyl, pentyl, hexyl and the like; It is intended that C1-20 alkyl include C1-6 alkyl and its higher homologues having 7 to 20 carbon atoms such as, for example, heptyl, octyl, nonyl decyl and the like. In a preferred embodiment, R3 is methyl and R3 is n-butyl; and Ra, X is CH3-SO2-O-; R1 and R2 are Rb Rc and Rd are each n-butyl; where 1-MCP is prepared as follows: CH3 °VO AÍCHi Si—n-Bu (trans) CH3 n-Bu 1+ n-Bu—N—n-Bu F n-Bu solvent ch3 A n-BuN OSO2CH3 n-Bu-SI(CH3)2-F carrier gas washing solution CH3 In another embodiment of the 1-MCP generating device of the present invention, the second container is equipped with a heating element. When the 1-MCP generating device is used, the second container is heated to a temperature between 30°C and 50°C, more specifically to a temperature between 40°C and 45°C. The 1-MCP precursor of formula (I) can be used dissolved in a solvent such as DMF, DMSO, or dimethylacetamide, or it can also be used alone (i.e., undissolved). A special 1-MCP precursor of formula (I) is trans-1-methyl-1-(methanesulfonyloxy)-2-(butyldimethylsilyl)cyclopropane as used in the reaction scheme above. The fluoride ion-containing compound of formula (II) can be used dissolved in a solvent such as DMF, DMSO, or dimethylacetamide, rather than used alone. A preferred solvent is DMSO. The solvent can be used in an amount 0.5 to 3.0 times the amount of the fluoride ion-containing compound, but if only a small amount of 1-MCP is required, the solvent can be used in an amount 10 times the amount of the fluoride ion-containing compound. A preferred fluoride ion-containing compound of formula (II) is tetrabutylammonium fluoride (TBAF). The 1-MCP precursor of formula (I) and the fluoride ion-containing compound of formula (II) can simply be mixed or brought into contact with each other, thereby obtaining 1-MCP. To facilitate mixing, the container (2) can be equipped with a mixing device. The amount of fluoride ion-containing compound is 1 to 3 mol per 1 mole of the 1-MCP precursor. A preferred amount of fluoride ion-containing compound is 2.7 mol per 1 mole of the 1-MCP precursor. The carrier gas used in the 1-MCP generating device can be air or any inert gas such as nitrogen. Before the carrier gas releases the 1-MCP gas prepared by the reaction of the 1-MCP precursor of formula (I) and the fluoride ion-containing compound of formula (II) to the outside, the 1-MCP gas is passed through a scrubbing solution that removes reaction byproducts such as halosilane or acidic byproducts such as HE by decomposition or neutralization. The scrubbing solution is a basic aqueous solution prepared by dissolving NaOH, KOH, Na₂CO₃, NaHCO₃, K₂CO₃, KHCO₃, Na₂SiO₂, K₂SiO₂, sodium methanolate, sodium ethanolate, or sodium isopropanolate. A preferred scrubbing solution is a 0.1 M aqueous sodium hydroxide solution. In general, 1-MCP has a sufficient effect on the air even at a low concentration of 1 ppm or less, and therefore approximately 0.01 to 5.0 liters (0.45 to 220 mmol) of 1-MCP are needed to treat warehouses from 10 m3 to 5000 m3. Depending on the size of the warehouse, more than one 1-MCP generating device can be used. In the 1-MCP generating device, the amount of the 1-MCP precursor is in the range of approximately 50 mg to approximately 30 g, and the amount of the solution of the compound containing fluoride ion is in the range of approximately 0.1 mL to approximately 200 mL, and therefore a container having a volume between 1 mL and 500 mL can be used as a first container and a second container. The magnitude of the flux used in the 1-MCP generating device of the present invention has Optimized to achieve both high 1-MCP yield and minimal impurities, a flow rate of 50 ± 10 SCCM (corresponding to 53.6 ± 10.7 cm³ / min at standard temperature and pressure) has been found to be optimal. This optimal flow rate can be used for a 1-MCP generating device of the present invention where the first, second, and third vessels range in size from 20 mL to 500 mL. The user will appreciate that adjusting the flow rate will be necessary for extremely large vessel sizes. The materials and types of the first and second vessels of the 1-MCP generating device are not specifically limited, provided they have a structure capable of stably storing the materials used and, if necessary, dispensing the produced materials. For example, the first and second vessels can be any container with an inlet and outlet, made of a material inert to the material being stored. Specifically, widely used resins such as polyethylene and polypropylene can be used due to their durability, light weight, and low cost. A fluorinated resin such as polytetrafluoroethylene (PTFE) can also be used for its durability, light weight, ease of handling, and reliability. Examples 1) Synthesis of 1-methylcyclopropene (refer to Figure 3 for system configuration) First, 150 mL plastic containers made of polyethylene were prepared for use as a first, second, and third container, respectively. The plastic containers were coupled with a stopper unit of a 1MCP generating device so that, except for their inlets and outlets, they were sealed. Tubing was inserted into the inlets and outlets of the first, second, and third containers so that the outlet of the first container was connected to the inlet of the second container, and the outlet of the second container was connected to the inlet of the third container. A solution of 18.9 g (72.3 mmol) of tetrabutylammonium fluoride (TBAF) in 21.5 mL of DMSO was introduced into the first container. trans-l-methyl(methanesulfonyloxy)-2-(butyldimethylsilyl)cyclopropane (6.5 g = 24.6 mmol) was injected as a precursor to 1-MCP into the second container, and the temperature of the second container was maintained at 40°C using a thermostat. The third container was filled with 115 g of a 0.1 M aqueous NaOH solution. An air pump (Thomas model 2002VD / 0.5 / E / LC diaphragm air pump) was connected via tubing to the inlet of the first vessel, and air was continuously flowed into the first vessel at a flow rate of approximately 250 mL / min for 2 hours. The flow rate was measured using a mass flow sensor (Honeywell AWM3100), and a feedback control circuit regulated the air pump speed to maintain a constant flow rate. A flow restrictor was an orifice disc with a 0.15 mm diameter hole. The gas was vented through the third vessel from the second vessel and collected in a 1 m³ container (IBC). After 2.5 hours, a sample was taken from the IBC and analyzed using the following GC procedure. The yield of 1-MCP, total amount of impurities, and amount of butyldimethylsilyl fluoride (main impurity) are listed in Table 1. 2) Synthesis of 1-methylcyclopropene (refer to Figure 3 for system configuration) First, 150 mL plastic containers made of polyethylene were prepared for use as a first, second, and third container, respectively. The plastic containers were coupled with a stopper unit of a 1MCP generating device so that, except for their inlets and outlets, they were sealed. Tubing was inserted into the inlets and outlets of the first, second, and third containers so that the outlet of the first container was connected to the inlet of the second container, and the outlet of the second container was connected to the inlet of the third container. A solution of 18.9 g (= 72.3 mmol) of tetrabutylammonium fluoride (TBAF) in 21.5 mL of DMSO was introduced into the first container. trans-l-methyl(methanesulfonyloxy)-2-(butyldimethylsilyl)cyclopropane (6.5 g = 24.6 mmol) was injected as a precursor to 1-MCP into the second container, and the temperature of the second container was maintained at 40°C using a thermostat. The third container was filled with 115 g of a 0.1 M aqueous NaOH solution. An air pump (Thomas model 2002VD / 0.5 / E / LC diaphragm air pump) was connected via tubing to the inlet of the first container, and air was continuously flowed into the first container at a flow rate of approximately 52 mL / min for 2 hours. The flow rate was measured using a mass flow sensor (Honeywell AWM3100), and a feedback control circuit regulated the speed of the air pump. to maintain a constant flow rate. A flow reducer was an orifice disk with a 0.15 hole mm in diameter. The gas was poured through the third container from the second container and collected in a 1 m3 container (IBC container). A sample was taken after 2.5 hours. from the IBC container and was analyzed using the following GC procedure. The yield of 1-MCP and the amount of butyldimethylsilyl fluoride as the main impurity are listed in Table 1. GC Procedure: GC System Parameters Column: ZB-624 (30 m x 0.25 mm id, 1.4 pm film thickness) or equivalent Injector Temperature of 75°C entrance: Gas sampling valve technique with a 1 mL injection loop. Manual injection that applies 10 mL of gas to the loop. Volume of 1 mL injection: Carrier gas, Helium (19.9 psi) or equivalent magnitude of flow: Temperature of the programmed execution: oven: Speed ​​Temperature (°C / min) (°C) initial na 40 Ramp 1 25 165 Detector: FID Detector temperature of 185°C: Detector gas: air: 400 mL / min. Hydrogen: 30 mL / min. Compensation (helium): 30 mL / min. Table 1: Flow rate: 250 mL / min. Flow rate: 52 mL / min 1-MCP yield 92.2% 83.9% Fluoride of 2.17% relative to 0.43% relative to butyldimethylsilyl 1-MCP 1-MCP The lower flow magnitude in Example 2 of 52 mL / min produces 1-MCP with a much smaller amount of impurities compared to the upper flow magnitude of 250 mL / min used in Example 1. 3) Variation of the magnitude of the flow between the mechanical needle valve and the pump regulated with an electronic flow control circuit and mass flow sensor a)_ Device _ _ generator_ of_ 1 - MC P _with a mechanical guide The 1-MCP generating device as used in Example 2 was equipped with a needle valve for mechanical flow control, as used in the prior art device of WO2012 / 134088. The flow rate was set to 53 mL / min, and the 1-MCP generator was operated for one hour. The flow rate at the outlet (12) was measured at various times during the one-hour run. The flow rate was measured over a one-minute period, and the minimum and maximum flow rates were recorded. Different runs on different days resulted in different flow rates, and the minimum and maximum measured flow rates are listed in Table 2. Table 2: Magnitude of flow measured at outlet (12) for a 1-MCP generator with needle valve Measurement Day 1 Magnitude of Magnitude of Time Difference Minimum Flow Maximum Flow (mL / min) (mL / min) (mL / min) (mL / min) 1 41 47 6 13 40 48 8 ............. ...____ _______... ___________________ ___ 21 38 48 10 34.................38 ........ 4 8 ' '.10 58 39 48 9 Average 39 48 9 Measurement Day 2 Magnitude of Magnitude of Time Difference Minimum Flow Maximum Flow (mL / min) (mL / min) (mL / min) (mL / min) 1 58 63 5 ..._________________ . . .._.... ...... . ______ ________ ____ _____ 7 48 62 14 ' 47~ ~ 61 ' ” Ϊ4 37 43 61 18 51 43 62 19 ” 68 47 61 average 48 62 14 Measurement Day 3 Magnitude of Magnitude of Time Difference Minimum Flow Maximum Flow (mL / min) (mL / min) (mL / min) (mL / min) 1 14 26 12 12 14 27 13 33 16 26 10 43 14 28 14 Average 15 27 12 Conclusion: A 1-MCP generating device equipped with a mechanical needle for flow control not only demonstrates a large difference in the magnitude of the flow measured at the outlet (12) but also large differences in the mean flow magnitude between different measurement days with no change from the initial flow magnitude of 53 mL / min between measurement days. b)__ D_i spo_sit i vo _generator_ d_e _ 1 pMCP_ c_qn_ se:nsor__de 1__f 1 u_j_q more s ico_ y_ .circuí t o_ _de_ c_qn t r_ql _ del _ fl_u jo The 1-MCP generator from Example 2 was used, with the flow rate set to 53 mL / min. The 1-MCP generator was run for two hours, and the flow rate at outlet (12) was measured at various times during the two-hour run. The flow rate was measured for one minute, and the minimum and maximum flow rates were recorded. Different runs on different days resulted in different flow rates, and the minimum and maximum measured flow rates are listed in Table 3. Table 3: Magnitude of flow measured at outlet (12) for a 1-MCP generator with mass flow sensor Measurement Day 1 Time (minute) Minimum flow magnitude (mL / min) Maximum flow magnitude (mL / min) Difference (mL / min) 20 50 57 7 30 51 56 5 40 50 57 7 50 51 56 5 60 50 56 6 7 0 51 56 5 80 52 56 4 90 51 56 5 100 51 57 6 110 51 5 6 5 .............118 57 6 average 51 56 5.4 Measurement Day 2 magnitude of magnitude of Time difference flow minimum flow maximum (mL / min) (mL / min) (mL / min) (mL / min) 10 53 58 5 20 53 59 6 30 53 59 6 40 53 5 9 6 50 53 59 6 60 52 59 7 70 .......... 54 59 5 .................80.............................~ ................................. 55............................... 59 ...............................................4........................... 90 53 59 6 100 53 59 6 118 54 58 4 average 53 59 5.2 Conclusion: A 1-MCP generating device according to the present invention demonstrates low variation in the magnitude of the flow at the outlet (12), differing little from one day of measurement to another. The minimum and maximum measured flow magnitudes remained within 20% of the desired flow magnitude of 53 mL / min.

Claims

1. A 1-methylcyclopropene (1-MCP) generating device comprising: a first container comprising an inlet, an outlet, and a fluoride ion-containing compound of formula (II) FORMULA where R a , R b , R cy R d are each independently selected from C1-20 alkyl, phenyl, and naphthyl; a second container comprising an inlet, an outlet, and a 1-MCP precursor of formula (I) FORMULA (I) where X is halogen, or (C1-6 alkyl)-S(O)2O-; and R 1 , R 2 and R 3 are each independently selected from hydrogen, C1-6 alkyl, phenyl, C1-6 alkyloxy, and halogen; a third container comprising an inlet, an outlet, and a washing solution;and a pump for supplying a carrier gas that is introduced into the first container to transfer the fluoride ion-containing compound of formula (II) to the second container where said fluoride ion-containing compound of formula (II) reacts with the 1-MCP precursor of formula (I) and the resulting 1-MCP is transferred with the carrier gas to the third container where it is bubbled through the washing solution before the carrier gas with the 1-MCP is released to the outside; characterized in that the magnitude of the carrier gas flow is regulated by a mass flow sensor that provides a flow magnitude signal to a flow control circuit that provides the pump with a modulating signal to regulate the magnitude of the carrier gas flow, and in that a flow reducer is present between the pump and the mass flow sensor. Thirteen claims follow;