Jul. 4, 2019  5  US 2019/0204738 Al  hydrocarbon group which may have a substituent and a  divalent linking group having hetero atoms.  [0076]  As W, a group represented by Chemical Formula:  CH 2 =C(R)-Yaxo_ is suitably exemplified. In this chemical  formula, R represents a hydrogen atom, an alkyl group  having  1  to 5 carbon atoms, or a halogenated alkyl group  having  1  to 5 carbon atoms, and  Yaxo  represents a single  bond or a divalent linking group.  [0077]  In the chemical formula shown above, as the alkyl  group having  1  to 5 carbon atoms as R, a linear or branched  alkyl group having  1  to 5 carbon atoms is preferable, and  specific examples thereof include a methyl group, an ethyl  group, a propyl group, an isopropyl group, an n-butyl group,  an isobutyl group, a tert-butyl group, a pentyl group, an  isopentyl group, and a neopentyl group. The halogenated  alkyl group having  1  to 5 carbon atoms is a group in which  some or all hydrogen atoms of the above-described alkyl  group having  1  to 5 carbon atoms have been substituted with  halogen atoms. Examples of the halogen atom include a  fluorine atom, a chlorine atom, a bromine atom, and an  iodine atom, and a fluorine atom is particularly preferable.  As R, a hydrogen atom, an alkyl group having  1  to 5 carbon  atoms, or a fluorinated alkyl group having  1  to 5 carbon  atoms is preferable, a hydrogen atom or a methyl group is  more preferable, and a methyl group is particularly prefer› able in terms of industrial availability.  [0078]  In the chemical formula shown above, the divalent  linking group as  Yaxo  is not particularly limited, and suitable  examples thereof include a divalent hydrocarbon group  which may have a substituent and a divalent linking group  having hetero atoms.  [0079]  Divalent Hydrocarbon Group which May have  Substituent:  [0080]  In a case where  Yaxo  represents a divalent hydro› carbon group which may have a substituent, the hydrocar› bon group may be an aliphatic hydrocarbon group or an  aromatic hydrocarbon group.  [0081]  Aliphatic Hydrocarbon Group as  Yax 0  [0082]  The aliphatic hydrocarbon group indicates a hydro› carbon group that has no aromaticity. The aliphatic hydro› carbon group may be saturated or unsaturated. In general,  the aliphatic hydrocarbon group is preferably saturated.  [0083]  Examples of the aliphatic hydrocarbon group  include a linear or branched aliphatic hydrocarbon group,  and an aliphatic hydrocarbon group containing a ring in the  structure thereof.  [0084]  Linear or Branched Aliphatic Hydrocarbon Group  [0085]  The linear aliphatic hydrocarbon group has prefer› ably  1  to  10  carbon atoms, more preferably  1  to 6 carbon  atoms, still more preferably  1  to  4  carbon atoms, and most  preferably  1  to 3 carbon atoms.  [0086]  As the linear aliphatic hydrocarbon group, a linear  alkylene group is preferable. Specific examples thereof  include a methylene group [-CH 2 -], an ethylene group  [-(CH 2 ) 2 -], a trimethylene group [-(CH 2 )$_{3}$ -],  a tetram› ethylene group [-(CH 2 )$_{4}$ -]  and a pentamethylene group  [-(CH2)s-l- [0087]  The branched aliphatic hydrocarbon group has  preferably  2  to  10  carbon atoms, more preferably 3 to 6  carbon atoms, still more preferably 3 or  4  carbon atoms, and  most preferably 3 carbon atoms.  [0088]  As the branched aliphatic hydrocarbon group, a  branched alkylene group is preferred, and specific examples  thereof include alkylalkylene groups, for example, alkylm- [0096]  The alkoxy group as the substituent is preferably an  alkoxy group having  1  to 5 carbon atoms, more preferably  a methoxy group, an ethoxy group, an n-propoxy group, an  iso-propoxy group, an n-butoxy group or a tert-butoxy  group, and most preferably a methoxy group or an ethoxy  group.  [0095]  The alkyl group as the substituent is preferably an  alkyl group having  1  to 5 carbon atoms, and a methyl group,  an ethyl group, a propyl group, an n-butyl group or a  tert-butyl group is particularly preferable.  [0094]  The cyclic aliphatic hydrocarbon group may or  may not have a substituent. Examples of the substituent  include an alkyl group, an alkoxy group, a halogen atom, a  halogenated alkyl group, a hydroxyl group, and a carbonyl  group.  [0093]  The cyclic aliphatic hydrocarbon group may be a  polycyclic group or a monocyclic group. As the monocyclic  alicyclic hydrocarbon group, a group in which  2  hydrogen  atoms have been removed from a monocycloalkane is pref› erable. The monocycloalkane has preferably 3 to 6 carbon  atoms, and specific examples thereof include cyclopentane  and cyclohexane. As the polycyclic alicyclic hydrocarbon  group, a group in which two hydrogen atoms have been  removed from a polycycloalkane is preferable. As the poly› cycloalkane, a group having 7 to 12 carbon atoms is pref› erable. Examples of the polycycloalkane include adaman› tane,  norbomane,  isobornane,  tricyclodecane,  and  tetracyclododecane.  [0092]  The cyclic aliphatic hydrocarbon group has pref› erably 3 to 20 carbon atoms and more preferably 3 to 12  carbon atoms.  [0091]  Examples of the aliphatic hydrocarbon group con› taining a ring in the structure thereof include a cyclic  aliphatic hydrocarbon group which may have a substituent  containing a hetero atom in the ring structure thereof (a  group in which two hydrogen atoms have been removed  from an aliphatic hydrocarbon ring), a group in which the  cyclic aliphatic hydrocarbon group is bonded to the terminal  of a linear or branched aliphatic hydrocarbon group, and a  group in which the cyclic aliphatic hydrocarbon group is  interposed in a linear or branched aliphatic hydrocarbon  group. As the linear or branched aliphatic hydrocarbon  group, the same groups as those described above can be  used.  [0090]  Aliphatic Hydrocarbon Group Containing Ring in  Structure Thereof  [0089]  The linear or branched aliphatic hydrocarbon  group may or may not have a substituent. Examples of the  substituent include a fluorine atom, a fluorinated alkyl group  having  1  to 5 carbon atoms which has been substituted with  a fluorine atom, and a carbonyl group.  ethylene groups such as ----CH(CH$_{3}$)-, ----CH(CH 2 CH$_{3}$)-,  ----C(CH$_{3}$ ) 2 -,  -C(CH$_{3}$)(CH 2 CH$_{3}$)-,  -C(CH$_{3}$ )  (CH 2 CH 2 CH$_{3}$)-, and -C(CH 2 CH$_{3}$ ) 2 -; alkylethylene  groups such as ----CH(CH$_{3}$)CH 2 -,  ----CH(CH$_{3}$)CH(CH$_{3}$)-,  ----C(CH$_{3}$ ) 2 CH 2 -,  -CH(CH 2 CH$_{3}$)CH 2 -,  and  ----C(CH 2 CH$_{3}$ ) 2 ----CH 2 -; alkyltrimethylene groups such as  ----CH(CH$_{3}$)CH 2 CH 2 -, and ----CH 2 CH(CH$_{3}$)CH 2 -; and  alkyltetramethylene  groups  such  as  -CH(CH$_{3}$ )  CH 2 CH 2 CH 2 -, and ----CH 2 CH(CH$_{3}$)CH 2 CH 2 -. As the  alkyl group in the alkylalkylene group, a linear alkyl group  having  1  to 5 carbon atoms is preferable. 