31  5,763,670  32  As  indicated  above.  it is  generally  preferred  to carry  out  the  hydroformylation  processes  of this  invention  in a  con› tinuous  manner.  In  general.  continuous  hydroforrnylation  processes  are  well  known  in the  art and  may  involve:  (a)  hydrofonnylating  the  olefinic  starting  material(s)  with  car- bon  monoxide  and  hydrogen  in a  liquid  homogeneous  reaction  mixture  comprising  a  solvent,  the  metal› organopolyphosphite  ligand  complex  catalyst,  and  free  orga› nopolyphosphite  ligand;  (b)  maintaining  reaction  tempera› ture  and  pressure  conditions  favorable  to  the  hydroformylation  of the  olefinic  starting  material(s);  (c)  supplying  make-up  quantities  of the  olefinic  starting  material(s).  carbon  monoxide  and  hydrogen  to the  reaction  medium  as  those  reactants  are  used  up;  and  (d)  recovering  the  desired  aldehyde  hydroformylation  product(s)  in any  manner  desired.  The  continuous  process  can  be  carried  out  in a  single  pass  mode,  i.e.,  wherein  a  vaporous  mixture  comprising  unreacted  olefinic  starting  material(  s) and  vapor› ized  aldehyde  product  is  removed  from  the  liquid  reaction  mixture  from  whence  the  aldehyde  product  is  recovered  and  make-up  olefinic  starting  material(s),  carbon  monoxide  and  hydrogen  are  supplied  to the  liquid  reaction  medium  for the  next  single  pass  without  recycling  the  unreacted  olefinic  starting  material(s).  Such  types  of  recycle  procedure  are well  known  in the  art and  may  involve  the  liquid  recycling  of the  metal-organopolyphosphite  complex  catalyst  fluid  separated  from  the  desired  aldehyde  reaction  product(s),  such  as  disclosed,  for  example,  in  U.S.  Pat.  No.  4.148,830  or a  gas  recycle  procedure  such  as  disclosed.  for  example.  in  U.S.  Pat.  No.  4.247  .486,  as  well  as a  combination  of  both  a  liquid  and  gas  recycle  procedure  if  desired.  The  disclosures  of said  U.S.  Pat.  Nos.  4,148,830  and  4.247,486  are  incorporated  herein  by  reference  thereto.  The  most  preferred  hydroformy- Accordingly  illustrative  non-optically  active  aldehyde  products  include  e.g .•  propionaldehyde.  n-butyraldehyde.  isobutyraldehyde,  n-valeraldehyde,  2-methyl  1-butyraldehyde,  hexanal,  hydroxyhexanal.  2-methyl  valeraldehyde,  heptanal,  2-methyl  1-hexanal,  octanal,  2-methyl  1-heptanal,  nonanal,  2-methyl-1-octanal,  2-ethyl  1-heptanal,  3-propyl  1-hexanal,  decanal,  adipaldehyde,  Illustrative  of  suitable  substituted  and  unsubstituted  alde- hyde  products  include  those  permissible  substituted  and  unsubstituted  aldehyde  compounds  described  in  Kirk› Othmer,  Encyclopedia  of  Chemical  Technology.  Fourth  Edition,  1996.  the  pertinent  portions  of  which  are  incorpo- rated  herein  by  reference.  The  hydroformylation  processes  encompassed  by  this  invention  are  also  conducted  in the  presence  of an  organic  solvent  for  the  metal-organopolyphosphite  ligand  complex  catalyst  and  free  organopolyphosphite  ligand.  The  solvent  may  also  contain  dissolved  water  up to  the  saturation  limit.  Depending  on  the  particular  catalyst  and  reactants  employed.  suitable  organic  solvents  include.  for  example.  alcohols.  alkanes,  alkenes,  alkynes.  ethers,  aldehydes,  higher  boiling  aldehyde  condensation  byproducts,  ketones,  esters,  amides,  tertiary  amines.  aromatics  and  the  like.  Any  suitable  solvent  which  does  not  unduly  adversely  interfere  with  the  intended  hydroformylation  reaction  can  be  employed  and  such  solvents  may  include  those  disclosed  heretofore  commonly  employed  in  known  metal  catalyzed  hydrofonnylation  reactions.  Mixtures  of one  or  more  dif› ferent  solvents  may  be  employed  if  desired.  In  general.  with  regard  to the  production  of  achiral  (non-optically  active)  aldehydes.  it is  preferred  to  employ  aldehyde  compounds  corresponding  to the  aldehyde  products  desired  to be  pro› duced  and/or  higher  boiling  aldehyde  liquid  condensation  byproducts  as the  main  organic  solvents  as is  common  in the  art.  Such  aldehyde  condensation  byproducts  can  also  be  preformed  if  desired  and  used  accordingly.  illustrative  pre› ferred  solvents  employable  in the  production  of  aldehydes  include  ketones  (  e.g.  acetone  and  methylethyl  ketone).  esters  (e.g.  ethyl  acetate).  hydrocarbons  (e.g.  toluene),  nitrohydro› carbons  (e.g.  nitrobenzene),  ethers  (e.g.  tetrahydrofuran  (fHF)  and  sulfolane.  Suitable  solvents  are  disclosed  in  U.S.  Pat.  No.  5.312,996.  The  amount  of  solvent  employed  is not  critical  to the  subject  invention  and  need  only  be that  amount  sufficient  to  solubilize  the  catalyst  and  free  ligand  of the  hydroformylation  reaction  mixture  to be  treated.  In  general,  the  amount  of  solvent  may  range  from  about  5  percent  by  weight  up to  about  99  percent  by  weight  or  more  based  on  the  total  weight  of the  hydroformylation  reaction  mixture  starting  material.  Illustrative  optically  active  aldehyde  products  include  (enantiomeric)  aldehyde  compounds  prepared  by the  asym› metric  hydroformylation  process  of this  invention  such  as,  e.g.  S-2-(p-isobutylphenyl)-propionaldehyde,  S-2-(6- methoxy-2-naph  thyl)propionaldehyde,  S-2-(3- benzoylphenyl)-propionaldehyde.  S-2-(p-thienoylphenyl)  propionaldehyde,  S-2-(3-fiuoro-4-phenyl)  phenylpropionaldehyde.  S-2-(  4-(  1.3-dihydro-1-oxo-2H› i  soi  n do  l- 2-y  l)  phenyl]  pr op  i  o  nal  de h  yd e.  S-2-(2- methylacetaldehyde)-5-benzoylthiophene  and  the  like.  The  hydrofonnylation  processes  of this  invention  are  conducted  for  a  period  of  time  sufficient  to  produce  the  desired  products.  The  exact  reaction  zone  residence  time  employed  is  dependent,  in  part,  upon  factors  such  as  temperature,  nature  and  proportion  of  starting  materials.  and  the  like.  The  reaction  zone  residence  time  will  normally  be  within  the  range  of  from  about  one-half  to  about  200  hours  or  more.  and  preferably  from  less  than  about  one  to  about  10  hours.  The  reaction  zone  residence  time  should  be  such  that  the  hydroformylation  process  can  be  operated  below  the  threshold  for  autocatalytic  hydrolysis  of  organopolyphos› phite  ligand  and  have  a  residence  time  in the  reaction  zone  sufficient  to  achieve  high  raw  material  efficiencies.  e.g.,  high  conversion  of  olefinic  unsaturated  compounds.  fonnylation  processes  of this  invention  is  preferably  below  the  threshold  level  that  causes  rapid  degradation  of the  organopolyphosphite  ligand,  i.e.,  below  the  threshold  for  autocatalytic  hydrolysis  of the  organopolyphosphite  ligand.  The  concentration  of  phosphorus  acidic  compounds  in the  hydroformylation  processes  of this  invention  is  such  that  the  pH  of said  reaction  product  fluid  is  from  about  4 to  about  9.  The  phosphorus  acidic  compound  concentration  is  prefer› ably  controlled  by  employing  an  aqueous  buffer  solution  as  described  herein.  2-methylglutaraldehyde,  2-methyladipaldehyde,  3-methyladipaldehyde,  3-hydroxypropionaldehyde,  6-hydroxyhexanal,  alkenals,  e.g .•  2-. 3- and  4-pentenal,  alkyl  5-formylvalerate.  2-methyl-1-nonanal.  undecanal,  2-methyl  1-decanal  dodecanal  2-methyl  1-undecanal.  tridecanal,  2-methyl  1-tridecanal,  2-ethyl.  1-dodecanal,  3-propyl-1- undecanal.  pentadecanal.  2-methyl-1-tetradecanal.  hexadecanal,  2-methyl-1-pentadecanal.  heptadecanal.  2-methyl-1-hexadecanal.  octadecanal.  2-methyl-1- heptadecanal.  nonodecanal.  2-methyl-1-octadecanal.  2-ethyl  1-heptadecanal,  3-propy  1-1-hexadecanal.  eicosanal.  2-methyl-1-nonadecanal.  heneicosanal.  2-methyl-1- eicosanal.  tricosanal.  2-methyl-1-docosanal.  tetracosanal.  2-methyl-1-tricosanal.  pentacosanal.  2-methyl-1- tetracosanal,  2-ethyl  1-tricosanal.  3-propyl-1-docosanal.  heptacosanal.  2-methyl-1-octacosanal.  nonacosanal.  2-methyl-1-octacosanal.  hentriacontanal.  2-methyl-1- triacontanal,  and  the  like. 