Mechanocaloric method

Abstract

A mechanocaloric method comprising altering a pressure applied to a mechanocaloric material sufficient to induce a phase change in the mechanocaloric material wherein the mechanocaloric material is an adamantane comprising a compound of formula (I): [Formula should be inserted here] wherein: R1 independently in each occurrence is selected from H or a monovalent substituent or the two R1 groups together with the C atom they are bound to form a group of formula C=O or C=S; R2 independently in each occurrence is selected from H or a monovalent substituent or the two R2 groups together with the C atom they are bound to form a group of formula C=O or C=S; R3 independently in each occurrence is selected from H or a monovalent substituent or the two R3 groups together with the C atom they are bound to form a group of formula C=O or C=S; R4 independently in each occurrence is selected from H or a monovalent substituent or the two R4 groups together with the C atom they are bound to form a group of formula C=O or C=S; and R5-R7 independently in each occurrence is selected from H or a monovalent substituent The mechanocaloric method may be a barocaloric method. The method may be used in heating or cooling.

Description

[0001] METHOD

[0002] Conventional cooling apparatus such as refrigerators and air conditioners contain a refrigerant fluid which cycles between a liquid phase and a gas phase. A disadvantage of such apparatus is the risk of atmospheric pollution arising from release of gaseous refrigerant into the atmosphere, for example due to a leak during the operational life of the apparatus or after its disposal or during servicing of the apparatus. Many refrigerants are potent greenhouse gases.

[0003] Alternative cooling methods make use of either a magnetocaloric effect, an electrocaloric effect or a mechanocaloric effect. The elastocaloric effect and the barocaloric effect are types of mechanocaloric effect.

[0004] The barocaloric effect is described in David Boldrin, "Fantastic barocalorics and where to find them" AppL Phys. Lett. 118, 170502, 2021 and L. Cirillo, A. Greco and C. Masselli, "Cooling through barocaloric effect: A review of the state of the art up to 2022", Thermal Science and Engineering Progress, Volume 33, 1 August 2022, 101380.

[0005] W02018 / 069506 discloses barocaloric cooling using organic materials.

[0006] EP4407011 discloses use of 2-amino-2-methyl-l,3-propanediol, m-carborane, 1-cyanoadamantane, 2-adamantanone and pentachloronitrobenzene as barocaloric materials used in a solid-state phase change heat storage and release method.

[0007] P.C. Knight and G.A. Cox, "The Electrical Conductivity and Crystal Phase Change in d-Camphor" Phys. Stat. Sol. 37, K39, 1970 discloses measurement of electrical conductivity of d-camphor in the region of a transition temperature.

[0008] CN118638123 discloses that camphor endosulfonamide is a reversible phase change material.

[0009] SUMMARY

[0010] The present disclosure provides a mechanocaloric method comprising altering a pressure applied to a mechanocaloric material sufficient to induce a phase change in the mechanocaloric material wherein the mechanocaloric material is a compound of formula (I):

[0011]

[0012] (I)

[0013] wherein:

[0014] R1independently in each occurrence is selected from H or a monovalent substituent or the two R1groups together with the C atom they are bound to form a group of formula C=O or C=S;

[0015] R2independently in each occurrence is selected from H or a monovalent substituent or the two R2groups together with the C atom they are bound to form a group of formula C=O or C=S;

[0016] R3independently in each occurrence is selected from H or a monovalent substituent or the two R3groups together with the C atom they are bound to form a group of formula C=O or C=S;

[0017] R4independently in each occurrence is selected from H or a monovalent substituent or the two R4groups together with the C atom they are bound to form a group of formula C=O or C=S;

[0018] and R5-R7independently in each occurrence is selected from H or a monovalent substituent.

[0019] Optionally, monovalent substituents of Rx-R7are independently selected from halogen, optionally halogenated methyl, hydroxymethyl, hydroxy and aldehyde.

[0020] Optionally, one R1is H or optionally halogenated methyl and the other R1is OH or halogen and, optionally, each R2is H.

[0021] Optionally, the two R1groups together with the C atom they are bound to form a group of formula C=O or C=S.

[0022] Optionally, the two R2groups together with the C atom they are bound to form a group of formula C=O or C=S.

[0023] Optionally, each R2is H.

[0024] Optionally, one of R5and R5is optionally halogenated methyl and the other of R5and R5is H.Optionally, each R3and each R4are H.

[0025] Optionally, each R7independently is optionally halogenated methyl.

[0026] Optionally, the compound of formula (I) is a chiral compound.

[0027] Optionally, an enantiomer of the compound of formula (I) is provided in an enantiomeric excess of at least 1%, optionally at least 10%, optionally at least 25%, optionally at least 50%.

[0028] The present disclosure provides a mechanocaloric method comprising altering a pressure applied to an organic mechanocaloric material sufficient to induce a phase change in the organic mechanocaloric material wherein the organic mechanocaloric material contains at least one stereocentre and wherein an enantiomer or diastereomer of the organic mechanocaloric material is provided in an enantiomeric or diastereomeric excess. The enantiomeric or diastereomeric excess may be at least 10%, optionally at least 25%, optionally at least 50%, optionally at least 90%.

[0029] Optionally, the mechanocaloric method is a heat transfer method.

[0030] Optionally, the heat transfer method is a cooling method. Optionally, the cooling method is cooling of a fluid of a refrigerator or an air conditioning unit.

[0031] Optionally, the heat transfer method is a heating method.

[0032] Optionally, the mechanocaloric method is a thermal storage method.

[0033] Optionally, the mechanocaloric method is a barocaloric method and the applied pressure is a hydrostatic pressure.

[0034] Optionally, the mechanocaloric method is an elastocaloric method and the applied pressure is a uniaxial pressure.

[0035] DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 schematically illustrates barocaloric apparatus according to some embodiments of the present disclosure;

[0037] Figure 2 is a phase diagram of (lR)-2-methyl-isoborneol as functions of temperature and pressure;

[0038] Figure 3 is a plot of pressure-induced isothermal entropy changes for the cooling and heating processes for (lR)-2-methyl-isoborneol;Figure 4 shows isothermally reversible entropy changes at variable pressures for (lR)-2-methyl-isoborneol;

[0039] Figures 5A is a schematic illustration of a die set for application and release of pressure; Figure 5B is a cross-section and side view of the die set of Figure 5A;

[0040] Figure 6A shows temperature change over 5 cycles upon application and release of different pressures on (-)-camphor; and

[0041] Figure 6B shows the first cycle of Figure 6A in more detail.

[0042] The drawings are not drawn to scale and have various viewpoints and perspectives. The drawings are some implementations and examples. Additionally, some components and / or operations may be separated into different blocks or combined into a single block for the purposes of discussion of some of the embodiments of the disclosed technology. Moreover, while the technology is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the technology to the particular implementations described. On the contrary, the technology is intended to cover all modifications, equivalents, and alternatives falling within the scope of the technology as defined by the appended claims.

[0043] DETAILED DESCRIPTION

[0044] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise," "comprising," and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to." Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word "or," in reference to a list of two or more items, covers all of the following interpretations of the word : any of the items in the list, all of the items in the list, and any combination of the items in the list. References to a chemical element include any isotope of that chemical element unless stated otherwise.

[0045] The teachings of the technology provided herein can be applied to other systems, not necessarily the system described below. The elements and acts of the various examples described below can be combined to provide further implementations of the technology.Some alternative implementations of the technology may include not only additional elements to those implementations noted below, but also may include fewer elements. These and other changes can be made to the technology in light of the following detailed description. While the description describes certain examples of the technology, and describes the best mode contemplated, no matter how detailed the description appears, the technology can be practiced in many ways. Details of the system may vary considerably in its specific implementation, while still being encompassed by the technology disclosed herein. As noted above, particular terminology used when describing certain features or aspects of the technology should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the technology with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the technology to the specific examples disclosed in the specification, unless the Detailed Description section explicitly defines such terms. Accordingly, the actual scope of the technology encompasses not only the disclosed examples, but also all equivalent ways of practicing or implementing the technology under the claims.

[0046] To reduce the number of claims, certain aspects of the technology are presented below in certain claim forms, but the applicant contemplates the various aspects of the technology in any number of claim forms.

[0047] In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of implementations of the disclosed technology. It will be apparent, however, to one skilled in the art that embodiments of the disclosed technology may be practiced without some of these specific details.

[0048] The present disclosure provides mechanocaloric materials which undergo a first-order phase change. Mechanocaloric materials described herein exhibit a reversible thermal response ( / .e., a change in temperature or entropy) caused by a pressure-induced first-order phase change. The first-order phase change may be a transition from a solid crystalline phase to a plastic crystal phase; a transition between two different plastic crystal phases; or a transition between two solid crystalline phases. Preferably, the mechanocaloric materials described herein have a crystalline phase and a plastic crystal phase. Preferably, the difference in the phase transition temperatures between a first to a second phase transition and the reverse second to first phase transition is no more than about 20°C, more preferably no more than about 10°C.

[0049] Optionally, the mechanocaloric compound has a plurality of phase changes, each phase change occurring at a different pressure. A cumulative mechanocaloric effect may beobtained by subjecting these materials to a pressure change sufficient to induce at least two of the phase changes. Preferably, the additive mechanocaloric effect (change in temperature or change in entropy) across the phase changes is greater than the mechanocaloric effect of a single phase change.

[0050] Mechanocaloric materials as described herein may be used in a heat transfer method in which pressure is applied to the mechanocaloric material sufficient to induce a phase change in the mechanocaloric material resulting in one of heat being released by the material (mechanocaloric effect) or heat being absorbed by the material (inverse mechanocaloric effect). Reduction of pressure sufficient to induce a reversal of this phase change results in the other of heat release by the material or heat absorption by the material.

[0051] Mechanocaloric materials as described herein may be used in a barocaloric method in which hydrostatic pressure is applied to the material or in an elastocaloric method in which a uniaxial pressure is applied to the material. References to a "pressure" herein includes both a hydrostatic pressure and a uniaxial pressure unless specifically stated otherwise. The mechanocaloric compounds described herein are in the solid state at the operating temperature and pressure. It will be understood that the operating temperature will depend on the temperature of the environment in which the mechanocaloric material is used, and the mechanocaloric material may be selected accordingly.

[0052] The pressure applied to a mechanocaloric compound described herein depends on the application and the operating temperature, i.e., temperature of the external environment. Preferably, the pressure applied to the mechanocaloric material is less than 1,000 Bar optionally at least 1 bar.

[0053] Preferably, the mechanocaloric materials described herein have a melting point in the range of 50-300°C, optionally 100-300°C, at atmospheric pressure.

[0054] Bornanes

[0055] The mechanocaloric materials described herein are bornanes which may be unsubstituted or substituted with one or more substituents.

[0056] Bornanes as described herein are compounds of Formula (I):

[0057]

[0058] (I)

[0059] R7-R7are each independently in each occurrence are selected from H or a monovalent substituent, and for one or more of Rx-R4the two R1groups, the two R2groups, the two R3groups and the two R4groups independently may together with the C atom they are bound to form a group of formula C=O or C=S. Optionally, only the two R1groups and I or the two R2groups may together with the C atom they are bound to form a group of formula C=O or C=S.

[0060] Monovalent substituents Rx-R7, if present, are preferably selected from halogen, optionally halogenated methyl, hydroxymethyl, hydroxy and aldehyde.

[0061] Halogenated methyl is preferably fluorinated methyl, chlorinated methyl or a combination thereof.

[0062] The, or each, halogen substituent of R7-R7may be selected from F, Cl, Br or I, preferably Cl or Br.

[0063] The, or each, optionally halogenated methyl may be selected from CH3, CH2CI, CH2F, CHF2 and CF3.

[0064] Preferably, one R1is H or optionally halogenated methyl and the other R1is OH or halogen, or the two R1groups together with the C atom they are bound to form a group of formula C=O or C=S.

[0065] Preferably, each R2is H or the two R2groups together with the C atom they are bound to form a group of formula C=O or C=S.

[0066] If one R1is H or optionally halogenated methyl and the other R1is OH or halogen then each R2is preferably H.

[0067] If the two R1groups together with the C atom they are bound to form a group of formula C=O or C=S then preferably each R2is H or the two R2groups together with the C atom they are bound to form a group of formula C=O or C=S.Preferably, one of R5and R5is optionally halogenated methyl and the other of R5and R5is H.

[0068] Preferably, each R3and each R4are H.

[0069] Preferably, each R7independently is optionally halogenated methyl.

[0070] The mechanocaloric material may have one or more stereocentres. Mechanocaloric materials having one stereocentre may be an enantiomer or a racemic mixture. A mixture may have an enantiomeric excess of at least 10 %, optionally at least 50 %, optionally at least 90 %. Mechanocaloric materials having more than one stereocentre may be a diastereomer or a mixture of diastereomers. The mixture may have a diastereomeric excess of a diastereomer. The diastereomeric excess may be at least 10 %, optionally at least 50 %, optionally at least 90 %.

[0071] Preferred chiral compounds of formula (I) are compounds in which R3is a substituent, preferably optionally halogenated methyl, and R4is H.

[0072] Exemplary compounds of formula (I) include the following compounds including racemic mixtures and enantiomers thereof:

[0073] OH

[0074]

[0075] Applications

[0076] A mechanocaloric cycle includes: application of pressure to the mechanocaloric material resulting in one of (i) absorption of heat by the mechanocaloric material and (ii) release of heat from the mechanocaloric material; and reduction or removal of the pressureresulting in the other of (i) absorption of heat by the mechanocaloric material and (ii) release of heat from the mechanocaloric material.

[0077] In some applications, the absorbed or released heat may be transferred away from the mechanocaloric material to provide heating or cooling, for example heating or cooling for an air conditioning unit or a refrigerator. Heat may be transferred using any known heat transfer fluid.

[0078] Figure 1 illustrates barocaloric apparatus 100 arranged to cycle a barocaloric material between a high-pressure state and a low-pressure state.

[0079] The apparatus comprises a pressure vessel 101 containing a fluid, more preferably a liquid, in which a barocaloric material 105 is dispersed. The fluid may be selected according to its compatibility with the mechanocaloric material; in particular, the fluid is suitably inert to the mechanocaloric material and the mechanocaloric material is suitably insoluble in the fluid at the operating temperature and pressure ranges of the apparatus. Exemplary fluids include, without limitation, water, alcohols and mixtures thereof; and oils. The barocaloric material may be in any suitable form, for example a powder dispersed in the fluid.

[0080] The apparatus comprises a mechanism 103, such as a piston, arranged to apply a hydrostatic pressure to the barocaloric material 105; and a heat transfer loop 107 arranged for flow of a heat transfer fluid into and out of the pressure vessel and including a heating element 109 and a cooling element 111.

[0081] In the case of a material exhibiting the barocaloric effect, the temperature of the barocaloric material 105 increases upon application of hydrostatic pressure sufficient to induce a phase change of the barocaloric material, heating a heat transfer fluid in the heat transfer loop 107. The applied hydrostatic pressure is preferably less than 1000 Bar. Heated fluid is delivered by a first valve arrangement 113 from the pressure chamber 101 to a heating element 111 and then returned via a second valve arrangement 115 to the pressure chamber 101.

[0082] The temperature of the barocaloric material reduces upon reduction of pressure sufficient to induce a phase change of the barocaloric material, cooling the heat transfer fluid flowing through the pressure chamber 101 in the heat transfer loop 107. Cooled fluid is delivered by the first valve arrangement 113 from the pressure chamber 101 to a cooling element 109 and then returned via the second valve arrangement 115 to the pressure chamber.The operation of the apparatus of Figure 1 is described above with reference to the barocaloric effect. It will be understood that the apparatus may also be used with a material exhibiting the inverse barocaloric effect.

[0083] Figure 1 illustrates apparatus in which heating or cooling is achieved through the barocaloric or inverse barocaloric effect. The same apparatus may be used for heating or cooling using an elastocaloric material in which pressure vessel 101 and mechanism 103 are replaced with a container for containing the elastocaloric material a mechanism arranged to apply uniaxial pressure to the elastocaloric material. The heat transfer loop 107 may form a coil within the pressure chamber.

[0084] The heating element 111 may be in the form of a coil.

[0085] The cooling element 109 may be in the form of a coil.

[0086] The mechanocaloric apparatus may be used to provide cooling in any object requiring cooling, for example a refrigerator, an air conditioner, cryogenics applications, or cooling of electronic equipment. The mechanocaloric apparatus may be used in any object requiring heating, for example a radiator or an oven.

[0087] In some applications, the absorbed heat may be stored.

[0088] Mechanocaloric materials as described herein may also be used in thermal batteries in applications such as waste heat management. In these applications, heat may be absorbed during a pressure-induced endothermic phase transition and delivered by a pressure-induced exothermic phase transition.

[0089] EXAMPLES

[0090] The following compounds were obtained from commercial sources: (+)-l, (±)-l, (+)-2 (Fluorochem), (-)-l, (-)-2, (-)-3, (+)-4a, (-)-4a, (±)-4b (Tokyo Chemical Industry, Ltd.), 2-bromoadamantane (Merck). The following compounds were prepared by dissolving an equimolar mixture of the individual enantiomers in dichloromethane, removal of solvent under reduced pressure and isolation the obtained solid: (±)-2, (±)-4a.

[0091] Differential scanning calorimetry measurements

[0092] Differential scanning calorimetry (DSC) was performed for compounds 1-5 illustrated in Table 1.

[0093] DSC measurements were performed on a Perkin Elmer DSC8500 using l-5mg of the compound and a scan rate of 5°C / minute. The hysteresis value of a compound as givenherein is the difference between the heating and cooling peak values taken from the compound's DSC measurements.

[0094] As set out in Table 1, Compounds 1-5 show low hysteresis (<12 K). Surprisingly, a larger entropy change is observed for enantiomers as compared to the corresponding racemic mixtures.

[0095] Table 1

[0096] 0

[0097] Compound 1: Camphor

[0098] Entropy Enantiomer

[0099] Heating Cooling onset Hysteresis change or racemic Mp (°C) onset (°C) (°C) (°C)

[0100] mixture (J K1

[0101] Kg1) (+)-l 175 -30 -38 8 261 (-)-l 176 -30 -37 7 284 (±)-l 171 -73 -72 1 21

[0102] Compound 2: Camphorquinone

[0103] Entropy Enantiomer

[0104] Heating Cooling onset Hysteresis change or racemic Mp (°C)

[0105] onset (°C) (°C) (°C)

[0106] mixture (J K1

[0107] Kg1) ( + )-2 200 61 49 12 227 (-)-2 199 62 52 10 245 (±)-2 199 39 30 9 135

[0108] /

[0109] S

[0110]

[0111] Compound 3: Thiocamphor

[0112] Entropy Enantiomer

[0113] Heating Cooling onset Hysteresis change or racemic Mp (°C)

[0114] onset (°C) (°C) (°C) mixture (J K1

[0115] Kg1) (-)-3 127 -20 -23 3 137

[0116] OH

[0117] Compound 4a: Borneol

[0118] Entropy Enantiomer change Heating Cooling onset Hysteresis or racemic Mp (°C)

[0119] onset (°C) (°C) (°C) mixture (J K1

[0120] Kg1) (+)-4a 206 (lit.) 68 68 0 32 (-)-4a 206 (lit.) 72 72 0 47 (±)-4a 208 (lit. + ) 69 70 -1 27

[0121] ^'■^OH

[0122] Compound 4b: Isoborneol

[0123] (±)-4b 210 (lit. + + ) -3 -1 2 48

[0124] Cl — ' O

[0125] Compound 5: 10 -chlorocamphor

[0126] (lS)-l-(chloromethyl)-7,7-dime thylbicyclo[2.2.1]heptan-2-one (±)-5 124 28 22 6 166

[0127]

[0128] + Prelog, V.; Wilhelm, M.; Bright, D. Bruce; Helvetica Chimica Acta (1954), 37, 221-4+ +Yu. S. Matveev et al, "Chiral derivatives of titanium with terpene alcohols", Russian Journal of General Chemistry, Volume 77, pages 1196-1203, (2007)

[0129] For the purpose of comparison, DSC was also performed for 2-bromoadamantane as set out in Table 2:

[0130] Table 2

[0131] Entropy

[0132] Mp (°C) Heating Cooling Hysteresis change onset (°C) onset (°C) (°C)

[0133] (J K1Kg1) 140 13 -1 14 185

[0134]

[0135] High-pressure differential scanning calorimetry measurements

[0136] Calorimetry measurements were performed on a Seteram MicroDSC7 EVO DSC equipped with a microcalvet sensor, using a pair of Hastelloy high-pressure DSC cells. Samples were loaded in air as received; a typical mass used was 15 mg. Isobaric measurements were performed at pressures between 0 and 1000 bar above atmospheric pressure, using nitrogen gas as a hydrostatic pressure transmitting medium, with pressures controlled using a Teledyne ISCO 65D Syringe Pump.

[0137] Results are set out in Table 3.

[0138] Table 3

[0139] AS

[0140] dT / dP

[0141] T (K)

[0142] (J K-l kg-1) High pressure (K kbar-1) RCP (kJ kg-1)

[0143] [heating, Hysteresis (K) Obar] [ib, heating,

[0144] [heating]

[0145] Compound 0 bar]

[0146] (lR)-2- 284 19.46 180 2 13.06 methyl- isoborneol

[0147]

[0148] Barocaloric coefficients (dT / dP)- describes sensitivity to pressure applied for the phase transition. This indicates performance and operating conditions of a barocaloric material dictating how large of a pressure shift (AP) is needed to induce a given thermal change (AT).

[0149] RCP (relative cooling power)- refer to the amount of heat that can be transferred between cold and hot reservoirs in a cycle.

[0150] Figure 2 is a phase diagram of (lR)-2-methyl-isoborneol as functions of temperature and pressure.

[0151] Figure 3 shows pressure-induced isothermal entropy changes for the cooling and heating processes for (lR)-2-methyl-isoborneol.

[0152] Figure 4 shows isothermally reversible entropy changes at variable pressures for (lR)-2-methyl-isoborneol.

[0153] Direct measurement of temperature change upon applying and releasing pressure With reference to Figure 5, measurements were made using a 6mm PPDS stainless-steel compression die set 500 having a cylindrical sample chamber 510 fitted with a piston 520 and a temperature sensor 530 having a thermistor (NTC Thermistor, 10 kohm) which records a temperature-dependent resistance. A thermocouple is in contact with the material through an opening at the bottom of the die set.

[0154] Measurements were made by placing a powder pellet sample material 540 in a plastic sleeve 550 on the die base 560 and applying a pressure to the piston 520 of the die through a pull tester (Mecmesin Imperial 2500, not shown). Pressure is applied for 3 minutes, then released for another 3 minutes before starting another compression / decompression cycle.

[0155] Applying pressure increases the temperature while releasing pressure decreases the temperature.

[0156] Resistance is converted into temperature through an appropriate calibration curve. The temperature sensor, in contact with the sample, is connected to a computer and this allows measurement of the sample temperature during the compression I decompression cycle. Multiple cycles are applied to the system to measure reproducibility and cyclability.

[0157] The compression / decompression cycles and the associated temperature change versus time are carried out at a controlled ambient temperature of 20°C.Figure 6A shows the temperature change across five compression / decompression cycles at different pressures. Figure 6A shows the first cycle in more detail.

Claims

CLAIMS1. A mechanocaloric method comprising altering a pressure applied to a mechanocaloric material sufficient to induce a phase change in the mechanocaloric material wherein the mechanocaloric material is a compound of formula (I):(I)wherein:R1independently in each occurrence is selected from H or a monovalent substituent or the two R1groups together with the C atom they are bound to form a group of formula C=O or C=S;R2independently in each occurrence is selected from H or a monovalent substituent or the two R2groups together with the C atom they are bound to form a group of formula C=O or C=S;R3independently in each occurrence is selected from H or a monovalent substituent or the two R3groups together with the C atom they are bound to form a group of formula C=O or C=S;R4independently in each occurrence is selected from H or a monovalent substituent or the two R4groups together with the C atom they are bound to form a group of formula C=O or C=S;and R5-R7independently in each occurrence is selected from H or a monovalent substituent.

2. The mechanocaloric method according to claim 1 wherein monovalent substituents of Rx-R7are independently selected from halogen, optionally halogenated methyl, hydroxymethyl, hydroxy and aldehyde.

3. The mechanocaloric method according to claim 1 or 2 wherein one R1is H or optionally halogenated methyl and the other R1is OH or halogen.

4. The mechanocaloric method according to claim 3 wherein each R2is H.

5. The mechanocaloric method according to claim 1 or 2 wherein the two R1groups together with the C atom they are bound to form a group of formula C=O or C=S.

6. The mechanocaloric method according to any one of the preceding claims wherein the two R2groups together with the C atom they are bound to form a group of formula C=O or C=S.

7. The mechanocaloric method according to any one of claims 1-5 wherein each R2is H.

8. The mechanocaloric method according to any one of the preceding claims wherein one of R5and R5is optionally halogenated methyl and the other of R5and R5is H.

9. The mechanocaloric method according to any one of the preceding claims wherein each R3and each R4are H.

10. The mechanocaloric method according to any one of the preceding claims wherein each R7independently is optionally halogenated methyl.

11. The mechanocaloric method according to any one of the preceding claims wherein the compound of formula (I) is a chiral compound.

12. The mechanocaloric method according to claim 11 wherein an enantiomer of the compound of formula (I) is provided in an enantiomeric excess.

13. A mechanocaloric method comprising altering a pressure applied to an organic mechanocaloric material sufficient to induce a phase change in the organic mechanocaloric material wherein the organic mechanocaloric material contains at least one stereocentre and wherein an enantiomer or diastereomer of the organic mechanocaloric material is provided in an enantiomeric or diastereomeric excess.

14. The mechanocaloric method according to any one of the preceding claims wherein the mechanocaloric method is a heat transfer method.

15. The mechanocaloric method according to claim 14 wherein the heat transfer method is a cooling method.

16. The mechanocaloric heat transfer method according to claim 15 wherein the cooling method is cooling of a fluid of a refrigerator or an air conditioning unit.

17. The mechanocaloric method according to claim 15 wherein the heat transfer method is a heating method.

18. The mechanocaloric method according to any one of claims 1-13 wherein the mechanocaloric method is a thermal storage method.

19. The mechanocaloric method according to any one of the preceding claims wherein the mechanocaloric method is a barocaloric method and the applied pressure is a hydrostatic pressure.

20. The mechanocaloric method according to any one of claims 1-18 wherein the mechanocaloric method is an elastocaloric method and the applied pressure is a uniaxial pressure.18

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