US 10,919,920 B2  33  34  (i) an  alkoxysilyl-containing  thiocarboxylic  acid ester of  the general formula  (I):  (ii) a thioester of the  general formula (II):  R$^{1}$[C(=O)SR$^{5}$]z  (II)  (I)  where R$^{1 }$is a monovalent group  selected from straight  chain alkyl group  containing from  1  to 18 carbon  atoms, a branched chain  alkyl group containing  from  3 to 18 carbon atoms,  a cycloalkyl  containing from  5 to 18 carbon atoms,  an alkenyl containing  from 2  to 18 carbon atoms,  an aryl containing  from 6 to 18  carbon atoms, aralkyl  containing from 7 to  18 carbon  atoms or hydrogen,  or is a divalent group  selected  from an alkyl containing  from  1  to  10  carbon atoms,  a cycloalkyl  containing from 5 to  10  carbon atoms or  phenyl;  each R  $^{2 }$is  independently  a divalent group selected  from  straight chain alkyl  group containing from  1  to  10  carbon atoms, a branched  chain alkyl group contain› ing from 3 to  10  carbon atoms, a cycloalkyl  group  containing from  5 to  10  carbon atoms, an  alkenyl  group containing from  2 to  10  carbon atoms, an aryl  group containing  from 6 to  10  carbon atoms or  aralkyl group containing  from 7 to  10  carbon atoms;  each R 3  is  independently  a  monovalent group  selected  from straight chain  alkyl group containing  from  1  to  6 carbon atoms, a  branched chain alkyl  group con› taining from 3 to 6  carbon atoms, a cycloalkyl  group  containing from  5 or 6 carbon atoms,  an alkenyl  group containing from  2 to 6 carbon atoms,  an aryl  group containing 6  carbon atoms or an  aralkyl group  containing from  7 to  10  carbon atoms;  R 4  is  independently  a  monovalent group  selected from  straight chain alkyl  group containing from  1  to 6  carbon atoms, a branched  chain alkyl group contain› ing from 3 to 6 carbon  atoms, a cycloalkyl  group  containing from  5 or 6 carbon atoms,  an alkenyl  group containing from  2 to 6 carbon atoms,  an aryl  group containing  6 carbon atoms,  aralkyl group  containing from  7 to  10  carbon atoms, a straight  chain alkyl group containing  2 to 6 carbon atoms  and  a hydroxyl group, an  alkyl group containing  at least  one oxygen atom  having the structure  -R  2  - (OCH$_{2}$CH$_{2}$)m(OCH$_{2}$ CH(CH$_{3}$))nOR 1  or a divalent  group formed from  two  R 4  groups being bonded  together through a  covalent bond, with  the provision  that (i) if two  R 4  groups are bonded  together, then a  is  O  or  1  and (ii) the sum of  m+n is from  1  to 20;  a, m, n and z are integers  wherein a is  0, 1  or 2, m is  from Oto  10,  n is from Oto  10  and z is  1  or 2, and  wherein  R 1  is a  monovalent group  selected from straight  chain  alkyl group containing  from  1  to 18 carbon atoms,  a  branched chain alkyl  group containing from  3 to 18  carbon atoms, a cycloalkyl  containing from 5  to 18  carbon atoms, an  alkenyl containing  from 2 to 18  carbon atoms, an aryl  containing from 6 to  18 carbon  atoms, aralkyl containing  from 7 to 18 carbon  atoms  or hydrogen, or is a  divalent group selected  from an  alkyl containing from  1  to  10  carbon atoms, a  cycloalkyl containing  from 5 to  10  carbon atoms or  phenyl;  each R 5  is  independently  a  monovalent group  selected  from straight chain  alkyl group containing  from  1  to  18 carbon atoms,  a branched chain  alkyl group  containing from 3  to 18 carbon atoms,  a cycloalkyl  group containing  from 5 to 18 carbon  atoms, an  alkenyl group containing  from 2 to 18 carbon  atoms,  an aryl group containing  from 6 to 18 carbon  atoms,  aralkyl group containing  from 7 to 18 carbon  atoms,  and wherein R $^{1 }$and z is an integer  wherein z is  1  or  2.  24.  The  alkoxysilyl-containing  thiocarboxylic  acid ester  composition  of claim  23  wherein the composition  contains  from about 70 to  about 99.9 weight  percent alkoxysilyl› containing thiocarboxylic  acid ester of formula  (I)  and from  0.1  to about 30 weight  percent thioester of  formula (II),  based on the total  weight of the  alkoxysilyl-containing  thiocarboxylic  acid of formula  (I)  and thioester of formula  (II).  25.  The  alkoxysilyl-containing  thiocarboxylic  acid ester  composition  of claim  23  further comprising  a mercapto› functional alkoxysilane  of general formula  (V):  HS-R$^{2}$-SiR$^{3}$a(OR 4 ) 3 ~  (V)  wherein  R 2 ,  R 3 ,  R 4  and a are defined above.  26.  The  alkoxysilyl-containing  thiocarboxylic  acid ester  composition  of claim  25  wherein the  mercapto-functional  alkoxysilane  of general formula  (V)  is from  0.1  to 50 weight  percent, based on  the total weight of  the  alkoxysilyl-con› taining thiocarboxylic  acid (i) and thioester  (ii).  27.  A rubber  composition comprising  the alkoxysilyl› containing thiocarboxylic  acid ester composition  of claim  23.  28.  The rubber composition  of claim  27  further compris› ing a  mercapto-functional  alkoxysilane  of formula (V).  *  *  *  *  * 