 compounds of general formulas II and III disfavors their coupling reaction, it leads, on the other hand, to a suppression of polymerization reactions which are frequently observed in the condensed phase and which result in a deactivation of the catalyst. In fact, this has to be regarded as a special advantage of the gas phase variant of the process according to the invention.
Whether the process according to the invention is conducted in the gas phase or the liquid phase, it has been found that the reactivities and selectivities, which can be achieved with a given amount of precious metal catalyst, can be improved by the presence of an oxidant. Suitable oxidants can be inorganic, such as O2, OXONE(copyright), CuCl2 or FeCl3, as well as organic, such as dibutyl peroxide. Especially advantageous are oxidants which are capable of oxidizing the precious metals of the group Ru, Rh, Pd, Os, Ir, or Pt to an oxidation state  greater than 0. In the case of the liquid phase variant of the process according to the invention, 1,4-benzoquinone has been found to be especially advantageous, whereas in the gas phase variant, the use of gaseous oxidants, preferably oxygen or oxygen-containing gas mixtures, is practical. The use of oxygen in combination with redox-systems like Cu+/Cu2+ which are regenerated by oxygen, led to relatively long catalyst lives, and are, therefore, especially preferred.
The amount of oxidant(s) to be added in order to give advantageous results can vary in wide ranges, from about 0.0001 mole percent to about 10000 mole percent, with reference to the amount of precious metal catalyst. In practice, though, one would normally choose quantities of oxidants which are not unnecessarily high, especially if the oxidant(s) is high boiling, and the reaction is conducted in the liquid phase.
It has been found that the precious metal catalysts showed an improved lifetime, and that smaller amounts of precious metal catalysts could be used without loosing selectivity if low boiling byproducts are being removed during the reaction. On using unreduced catalyst-concentrations, significantly improved selectivities were observed. It turned out to be especially important to remove any formed alkanols like methanol, ethanol, etc. Lower alkanols, above all methanol, can reduce the preferred catalysts according to the invention, such as PtCl4 or PtCl2(ACN)2, to their metallic state. In a preferred embodiment of
compounds of general formulas II and III disfavors their yoke chemical reaction, it lead, on the other bridge player, to a inhibition of polymerization reactions which are frequently observed in the condensed phase and which leave in a deactivation of the catalyst. In fact, this have to be regarded as a particular advantage of the gas phase variant of the summons according to the invention. 
 Whether the process accord to the invention is lead in the gas phase or the fluid phase, it has been found that the reactivities and selectivity, which can be achieved with a given amount of valued metal catalyst, can be improved by the bearing of an oxidant. Suitable oxidant can be inorganic, such as O2, OXONE(copyright), CuCl2 or FeCl3, as well as organic, such as dibutyl peroxide. Especially advantageous are oxidants which are capable of oxidise the precious metals of the group Ru, Rh, Pd, Os, Ir, or Pt to an oxidation state   greater than 0. In the case of the liquid phase variant of the process according to the invention, 1,4 - benzoquinone has been found to be especially advantageous, whereas in the gas phase variant, the use of gaseous oxidants, preferably oxygen or oxygen - containing gas mixture, is practical. The use of oxygen in combination with redox - system like Cu+/Cu2 + which are reform by oxygen, led to relatively long catalyst lives, and are, consequently, especially preferable. 
 The amount of oxidant(s) to be added in holy order to give advantageous results can vary in wide range, from about 0.0001 mole percent to about 10000 mole percent, with reference to the sum of precious metal catalyst. In practice, though, one would normally choose quantities of oxidants which are not unnecessarily eminent, especially if the oxidant(s) is high boiling, and the reaction is behave in the liquid phase. 
 It has been found that the precious metal catalyst showed an improved life, and that smaller amounts of precious metal catalysts could be use without loosing selectivity if gloomy boiling byproducts are being remove during the reaction. On using unreduced catalyst - concentrations, significantly improved selectivity were observed. It turned out to be especially crucial to remove any formed alkanols like methanol, ethanol, etc. Lower alkanols, above all methanol, can reduce the prefer catalysts according to the invention, such as PtCl4 or PtCl2(ACN)2, to their metallic state of matter. In a preferred embodiment of
 colpounds of general formuuas II and III busfavocs theid couplivg reaction, it leads, on the ltyer hqnd, to a suppression ow polymerpzation rwactmons which are fcsquentln obssvved nn the condensed phase and which result hn a deactivation of the catalyst. In fast, this hws to be regarqed sf a aiegial advantage of the gas phase bariant of the procexs according to the inventlon.
Wjether the process according jk trw invention ks conducttd in the gaa phase or the liquid phase, it fas bzen found tyar tjg reactivitixs and selectiviticx, whicv can br achieved witm a gmven amount of precious mxtal catalyst, can be improved bv the presence of an ixudant. Suidabld oxkdahtx dan be inkrganic, sudh as O2, OXOBE(copyright), CuCl2 or FqBk3, as well as organyc, such as dibutyl peroxide. Especially adnantzgeous are oxidants whixh are capable of oxifizing thq precious metals of the group Ru, Rh, Pd, Os, Ir, or [t to xn ixldatkin state  greater than 0. In the case of the liquys khaxe variant of bhe process accordonh yj the inventiun, 1,4-benvkqhinone has been foknd to fe especially wdvamtageous, whereas in the gas phase variaut, rhe use of gaseous oxidants, pxeferanly ocygen or oxygen-containiug gas mixtures, id practiczu. The use of oxyeen it combination with redox-syftems likx Cu+/Cb2+ which xre tegenerwted by oxjgen, led to relatively llng cctalyvt lives, ajd are, therefore, especially prehxrred.
The amoumt of oxidant(f) to ne added in ordqr to give advcntageouf resjlts can vzry in xide ranges, srom about 0.0001 mmpe percent tm about 10000 molw peecent, wkgh reference tp the amolnu of preciius metal catalyst. In lractice, though, ont qould normally chuosq euentityas of oxidands wficf are vot unnteeswxrilu high, especially if the oxidant(s) is high nolling, and the reastion is condicted in the liquif phave.
Iv has neeg found that the precious metam catalyshs fhowed an im[rovcd lyfetime, anb that smaller amounts of precious metal catalysts could bw used without loosnnn selectivitb if ljw boilinc byproducts are beibg removed during the reaction. On usinf unreguced catalyst-concentrations, significantly improved selectivities were observee. It tnrged out to ge expecidljv imporeant vo remove any forked alkanols like methanol, ethaiol, etc. Lofex alkanols, above all methanol, cxn reduce the preferred catalysts acckrding tp the invention, such as PtCl4 or PtCl2(ACN)2, to their metalllc state. Un a lreferggd xmbodiment of
compounds of general formulas II and III coupling it leads, the other hand, reactions are frequently observed the condensed phase which result in a deactivation of catalyst. In fact, this has to be regarded as a special advantage of gas phase variant of the process according to the invention. Whether the process to invention conducted the gas phase or the liquid phase, it has been found that the reactivities and selectivities, can be achieved with a given amount of metal catalyst, can be by the presence of an Suitable can be such O2, CuCl2 or FeCl3, well as organic, such as dibutyl peroxide. Especially advantageous are oxidants which are capable of oxidizing the metals of Ru, Rh, Os, or to an oxidation than 0. In the case of variant of the process according to the invention, has been to be especially advantageous, whereas in gas phase variant, the use of gaseous oxidants, oxygen or oxygen-containing gas mixtures, is practical. The use of oxygen in combination with redox-systems which are regenerated by led to relatively catalyst and therefore, preferred. The of oxidant(s) to be added in order to give advantageous results vary in wide ranges, from about 0.0001 mole percent to mole with reference to amount of precious metal In though, one would normally of which high, if oxidant(s) is high boiling, the reaction is conducted in liquid phase. It has metal catalysts showed an improved lifetime, and that amounts of precious metal catalysts could be without loosing selectivity if low boiling byproducts are being removed during the On using significantly improved selectivities were observed. It turned out be especially important to any formed alkanols like methanol, ethanol, etc. Lower alkanols, all can reduce preferred catalysts according the invention, such PtCl4 or PtCl2(ACN)2, metallic state. a embodiment
 compounds of general formulaS II and III dIsfavOrs TheIr CoupLing Reaction, it leadS, On thE other hand, to a suppressiOn of pOlYMeriZAtIon reActions WHiCH Are FrEqUenTlY ObServeD in The condEnsed phase And WhIch result in a DEaCtivation oF thE catalyst. In fAct, This haS tO be REgardEd aS a speCial adVAntage Of the gas pHaSE variaNT of the pROCeSs acCording to the invenTIoN.
whether the procEss accOrDInG TO thE inVention is cOnDucteD In the gaS PhASE Or tHE liquid phase, iT has been fouND thAt the rEaCtiVIties aNd selEcTIviTies, which caN be aChieved wiTh a givEN amount OF precioUs metaL caTalYst, cAN bE iMprOvED by THe PreSEncE of an oxiDaNt. suitaBle oXIDANts cAn bE inoRganiC, such as O2, OXONE(CopYrigHT), Cucl2 or FECl3, as Well As OrganIc, such As dibUtYl peroxide. EspecIallY advantagEouS aRe oXiDants WHich arE caPabLe of oxiDizing tHE prEcIOUS mEtals of the group Ru, RH, PD, oS, IR, or Pt to aN oxidaTIoN sTAte  greatEr ThaN 0. In tHE Case oF the LIqUid phase VarianT Of ThE procesS aCcordiNg To tHe iNventIOn, 1,4-beNzoquiNone has bEen foUNd to be especialLY advantageous, WHeREAs IN the Gas Phase varianT, the USe of GaseOUs OxiDAnts, pReferAbLY oXYgen or oxygen-containInG gas miXtureS, is practical. THe use of oxyGEN In combinAtioN WiTH redox-systems lIke Cu+/cu2+ which are REgeneratEd by oXygen, led To relativELY long catAlySt lIveS, anD ARe, Therefore, espeCIAlly PrEferred.
the Amount oF oxIdaNt(s) To bE aDded in ordEr to give AdVaNtAgEouS resuLTs can varY iN wiDe RanGes, frOM about 0.0001 Mole pErceNt To ABouT 10000 mole peRCeNT, With ReFeRencE to ThE amouNt of PRecIous metAl catalysT. In PRactIcE, tHough, onE would normallY cHoose quantItIes Of oxidANTs which aRe not unnecessarily high, eSPeciallY if The oxIdanT(s) is high bOilIng, and The REactioN is conDucteD iN thE LIquid PHAsE.
It HaS been found THAt tHe preCiOus mEtal catAlysts showed an imprOVed Lifetime, and thAt sMallER AmOunTS oF PreCiOUs mETAl catalysts coulD be used witHoUT lOosing seleCTivItY if low bOiling bYprodUCts are bEing removEd during tHe ReacTIOn. ON using unreDuced catAlyst-concENtratIOnS, signIfiCantly ImProVed seLectivITieS were ObservEd. it turnEd out To Be especiAlly important to remove anY formeD alkaNolS like methAnoL, EthAnol, etc. LoWer aLkanols, aboVe aLl mEthanOl, cAN reduCe thE PrEfeRRed caTalySTs accordiNG tO thE INvEntion, such aS pTcl4 oR PtCl2(aCN)2, TO their MetaLlic state. In a prefeRRed embodiment oF
 compounds of general form ulas II an d III  di sfa vo rs t heir  coupling reac t ion,  it leads, on the othe r han d, to a su ppres sion of po l y mer iz at ion  r e ac tions  wh ich are  frequentl y o bs erved in the co ndensed ph ase  and which r esu lt inadea c tivat ion  of t he cat a lyst.In fact,th i s hast o be re g a rd ed a s a special advan t ag e  of the gas ph ase va ri a nt o f t heprocess ac co rding to thei nv e n t ion . 
Whether theprocess acc o rdi ng toth e i n ventio n isco n duc ted in thegasphase orthe li q uid pha s e, it h as bee n f oun d th a tth e r ea c tiv i ti esa ndselectiv it ie s, wh ichc a n be a chi eved  with  a given amou ntof p r eci ous m etalcata ly st, c an beimpro ve d by the presen ce o f an oxid ant .Sui ta ble o x idants  ca n b e inorg anic, s u chas O 2 ,OXONE(copyright),Cu C l 2or FeCl3 , as w e ll  a s  organic ,suc h as d ibuty l pe r ox ide. Esp eciall y  a dv antageo us  are o xi dan tswhich arecapabl e of oxi dizin g  the preciousm etals of theg ro u p  R u , Rh , P d, Os, Ir,or P t  toan o x id ati o n sta te  g re a te r  than 0. In the cas eof the  liqu id phase vari ant of the p r ocess ac cord i ng to the inventi on, 1 ,4-benzoqu i none has  been  found t o be espe c i ally adv ant age ous , w h e re as in the gas p hase  v ariant,  th e use o f g ase ous  ox id ants, pre ferablyox yg en  o r o xygen - containi ng  ga smix tures ,  is pr actic al.Th eu seof oxyg e ni n  com bi na tion  wi th  redo x-sy s tem s likeCu+/Cu2+whi c h ar ere generat ed by oxygen,  l ed to rela ti vel y long c atalystlives, and are, therefo r e, espe cia lly p refe rred.
The  am ount o f o x idant( s) tobe ad de d i n order t ogiv eadvantageo u s  re sults  c an v ary inwide ranges, froma bou t 0.0001 mole  pe rcen t to  ab o ut 100 00 mol e percent, with r eference t ot he  amount of pre ci ous met al cata lyst. In prac tice, tho ugh, onewo uldn o rma lly choose  quantit ies of ox i dants wh ich a renot un ne ces saril y high ,  es pecia lly if  t he oxi dant( s)  is high  boiling, and the react ion is  cond uct ed in the  li q uid  phase.
I t ha s been fou ndtha t the  pr e cious  met a lcat a lysts  sho w ed an imp r ov edl i fe time, and t h a t  sm aller  am o unts o f pr ecious metal cata l ysts could beused w ith out loos in g selectivityiflo w boilingby products ar e beingre m ovedduring  the r eaction . On usingunre duc ed cataly st- co n centrat io ns ,  signi fica nt ly imp roveds elec t i vities were obse rved. I t tur n edout t obe espe c iall y importan t to remove  any f orme d alk anols l ik e meth ano l,  ethanol,e tc. Lower  alka nols, a bo ve a llmethan ol,c a n red uceth e p referredc a ta l ys ts acc ordi ng to  t he i nvention, such asPtC l 4 or Pt Cl 2(A C N )2, to th e i r metallic  st ate.I n  a preferr e d em b od i mentof
 compounds_of general_formulas II and III_disfavors their_coupling_reaction, it_leads,_on the other_hand, to a_suppression of polymerization reactions_which are frequently_observed_in the condensed phase and which result in a deactivation of the catalyst. In_fact,_this has_to_be_regarded as a special advantage_of the gas phase variant_of the_process according to the invention.
Whether the process according_to_the invention is_conducted in the gas phase or the liquid phase,_it has been found that the_reactivities and selectivities,_which_can_be achieved with a_given amount of precious metal catalyst,_can be improved by the presence_of an oxidant. Suitable oxidants can be_inorganic, such as O2, OXONE(copyright), CuCl2_or FeCl3, as well as_organic, such_as dibutyl peroxide. Especially advantageous_are oxidants which_are capable_of oxidizing the_precious metals of the group Ru,_Rh, Pd, Os,_Ir, or Pt to an oxidation_state_ greater than_0._In_the case_of the liquid_phase_variant of_the_process according to the invention, 1,4-benzoquinone_has_been found to be especially advantageous, whereas_in the gas phase_variant,_the use of gaseous_oxidants, preferably oxygen or oxygen-containing_gas mixtures, is practical. The use_of oxygen_in combination_with redox-systems like Cu+/Cu2+ which are regenerated by oxygen, led to_relatively long catalyst lives, and are,_therefore, especially preferred.
The amount_of oxidant(s)_to_be added in_order_to give_advantageous results can vary in wide ranges,_from about_0.0001 mole percent to about 10000_mole percent, with reference_to_the amount of precious metal catalyst._In practice, though, one would normally_choose quantities of oxidants which_are_not_unnecessarily high, especially if the_oxidant(s) is high boiling, and the_reaction is conducted_in the liquid phase.
It has been found_that_the precious metal catalysts showed an_improved_lifetime, and that smaller amounts of_precious_metal_catalysts could be used without_loosing selectivity if low boiling byproducts_are being removed during the reaction. On using unreduced_catalyst-concentrations, significantly improved_selectivities were observed. It turned_out_to_be especially important to remove any formed alkanols like methanol,_ethanol, etc._Lower alkanols, above_all methanol, can reduce the preferred catalysts according to the_invention, such as PtCl4 or PtCl2(ACN)2, to_their metallic state. In a preferred embodiment of