content_image/908339.jpg content_image/908340.jpg content_image/908351.jpg content_image/908341.jpg content_image/908342.jpg content_image/908343.jpg content_image/908344.jpg content_image/908345.jpg content_image/908346.jpg content_image/908347.jpg content_image/908348.jpg content_image/908349.jpg content_image/908350.jpg
in the case where Ra’ 4 to Ra’ 6 are not mutually bonded and independently represent a hydrocarbon group, the group represented by general formula (al-r2-2) shown below can be mentioned. 

<img src='content_image/908339.jpg'>

<img src='content_image/908340.jpg'>

In the formulae, Ra’ $^{10 }$represents an alkyl group of 1 to 10 carbon atoms; Ra’ 11 is a group which forms an aliphatic cyclic group together with a carbon atom having Ra’ 10 bonded thereto; and Ra,1 2 to Ra,1 4 each independently rep› resents a hydrocarbon group. 

[0203] In the formula (al-r2-1), as the alkyl group of 1 to 10 carbon atoms for Ra’ 10 , the same groups as described above for the linear or branched alkyl group for Ra’ 3 in the formula (al-r-1) are preferable. In the formula (al-r2-1), as the aliphatic cyclic group which is formed by Ra’$^{11 }$together with the carbon atom bonded to Ra’ 10 , the same groups as those described above for the monocyclic or polycyclic aliphatic hydrocarbon group for Ra’ $^{3 }$in the formula (al-r-1) are preferable. 

[0204] In the formula (al-r2-2), it is preferable that Ra’ 12 and Ra,1 4 each independently represents an alkyl group or 1 to 10 carbon atoms, and it is more preferable that the alkyl group is the same group as the described above for the linear or branched alkyl group for Ra’ $^{3 }$in the formula (al-r-1 ), it is still more preferable that the alkyl group is a linear alkyl group of 1 to 5 carbon atoms, and it is particularly preferable that the alkyl group is a methyl group or an ethyl group. 

[0205] In the formula (al-r2-2), it is preferable that Ra’ 13 is the same group as described above for the linear or branched alkyl group or monocyclic or polycyclic alicyclic hydrocarbon group for Ra’ 3 in the formula (al-r-1). Among these examples, monocyclic or polycyclic aliphatic hydro› carbon group for Ra’ 3 are more preferable. 

[0206] Specific examples of the group represented by the aforementioned formula (al-r2-1) are shown below. * rep› resents a valence bond (the same applies throughout the present specification). 

<img src='content_image/908351.jpg'>

<img src='content_image/908341.jpg'>

<img src='content_image/908342.jpg'>

<img src='content_image/908343.jpg'>

<img src='content_image/908344.jpg'>

<img src='content_image/908345.jpg'>

<img src='content_image/908346.jpg'>

<img src='content_image/908347.jpg'>

<img src='content_image/908348.jpg'>

<img src='content_image/908349.jpg'>

<img src='content_image/908350.jpg'>

-continued 

