The mechanism of the cycloaddition reaction of forming germanic bis-heterocyclic compound between singlet dichloro-germylene carbene and formaldehyde has been investigated with CCSD（T）//MP2/6-31G^＊ method, from the...The mechanism of the cycloaddition reaction of forming germanic bis-heterocyclic compound between singlet dichloro-germylene carbene and formaldehyde has been investigated with CCSD（T）//MP2/6-31G^＊ method, from the potential energy profile, we predict that the reaction has two competitive dominant reaction pathways. The presented rule of this reaction： the 2p unoccupied orbital of the C atom in dichloro-germylene carbene insert the π orbital of formaldehyde from oxygen side, resulting in the formation of intermediate. In the intermediate and between two reactants, because of the two bonding π orbital in dichloro-germylene carbene and formaldehyde have occurred [2＋2] cycloaddition reaction, forming two four- membered ring compounds in which Ge and O are in the opposite orientation and in the syn-position, respectively. Because of the unsaturated property of C atom from carbene in the two four-membered ring compounds, they further reacts with formaldehyde, resulting in the generation of two germanic bis-heterocyclic compounds.展开更多
The mechanism of the cycloaddition reaction of forming a silicic bis-heterocyclic compound between singlet dimethylmethylenesilylene （Me2C=Si：） and ethene has been investigated with the CCSD（T）//MP2/6-31G＊ metho...The mechanism of the cycloaddition reaction of forming a silicic bis-heterocyclic compound between singlet dimethylmethylenesilylene （Me2C=Si：） and ethene has been investigated with the CCSD（T）//MP2/6-31G＊ method. From the potential energy profile, it can be predicted that, this reaction has one dominant channel. The presented rule of this dominant channel： the 3p unoccupied orbital of Si in dimethylmethylenesilylene and the π orbital of ethene forming the π→p donor-acceptor bond, resulting in the formation of three-membered ring intermediate （INT1）; INT1 then isomerizes to a four-membered ring silylene （P2）, which is driven by ring-enlargement effect; due to sp3 hybridization of Si atom in P2, P2 further combines with ethene to form a silicic bis-heterocyclic compound.展开更多
The mechanism of the cycloaddition reaction between singlet dimethyl-silylene carbene and acetone has been investigated with density functional theory, From the potential energy profile, it can be predicted that the r...The mechanism of the cycloaddition reaction between singlet dimethyl-silylene carbene and acetone has been investigated with density functional theory, From the potential energy profile, it can be predicted that the reaction has two competitive dominant reaction pathways. The presented rule of this reaction： the [2＋2] cycloaddition effect between the πorbital of dimethyl-silylene carbene and the π orbital of π-bonded compounds leads to the formation of a twisty four-membered ring intermediate and a planar four-membered ring product; The unsaturated property of C atom from carbene in the planar four-membered ring product,resulting in the generation of CH3-transfer product and silicic bis-heterocyclic compound.展开更多
建立一种特殊医学用途配方乳粉中氯酸盐和高氯酸盐测定的超高效液相色谱-串联质谱法。样品用0.1%(体积比)甲酸水-乙腈提取,经Oasis PRiME HLB固相萃取柱净化,复合离子交换色谱柱分离后,以乙腈-20 mmol/L甲酸铵溶液为流动相进行梯度洗脱...建立一种特殊医学用途配方乳粉中氯酸盐和高氯酸盐测定的超高效液相色谱-串联质谱法。样品用0.1%(体积比)甲酸水-乙腈提取,经Oasis PRiME HLB固相萃取柱净化,复合离子交换色谱柱分离后,以乙腈-20 mmol/L甲酸铵溶液为流动相进行梯度洗脱,多反应模式检测,同位素内标法定量。结果显示,氯酸盐和高氯酸盐在1~200 ng/mL质量浓度范围内呈良好的线性关系,相关系数大于0.999,检出限为3.75μg/kg,定量限为7.5μg/kg。氯酸盐和高氯酸盐在7.5、50、500、1500μg/kg 4个加标水平回收率为97.1%~104.8%之间,相对标准偏差为2.55%~6.05%(n=6)。该方法简单快速、定量准确,能用于特殊医学配方乳粉中氯酸盐和高氯酸盐含量的测定。展开更多
X2Si=Ge： （X = H, Me, F, CI, Br, Ph, Ar...） is a new species. Its cycloaddition reaction is a new area for the study of germylene chemistry. The mechanism of cycloaddition reaction between singlet state Me2Si=Ge： a...X2Si=Ge： （X = H, Me, F, CI, Br, Ph, Ar...） is a new species. Its cycloaddition reaction is a new area for the study of germylene chemistry. The mechanism of cycloaddition reaction between singlet state Me2Si=Ge： and formaldehyde has been investigated with the CCSD（T）//MP2/cc-pvtz method. From the potential energy profile, it could be predicted that the reaction has one dominant reaction pathway. The reaction rule presented is that the two reactants first form a four-membered Si-heterocyclic ring germylene through the [2＋2] cycloaddition reaction. Because of the 4p unoccupied orbital of Ge： atom in the four-membered Si-heterocyclic ring germylene and the π orbital of formaldehyde form a π→p donor-acceptor bond, the four-membered Si-heterocyclic ring germylene further combines with formaldehyde to form an intermediate. Because the Ge atom in the intermediate undergoes sp^3 hybridization after transition state, then the intermediate isomerizes to a spiro-Ge-heterocyclic ring compound involving Si via a transition state. The research result indicates the laws of cycloaddition reaction between HzSi=Ge： and formaldehyde. It has important reference value for the cycloaddition reaction between X2Si=Ge： （X = H, Me, F, CI, Br, Ph, Ar…） and asymmetric to-bonded compounds, which is significant for the synthesis of small-ring and spiro-Ge-heterocyclic compounds involving Si. The study extends research area and enriches the research content of germylene chemistry.展开更多
The mechanism of cycloaddition reaction between singlet silylene carbene and acetone has been investigated with CCSD（T）//MP2/6-31G method. From the potential energy profile, it can be predicted that the reaction has...The mechanism of cycloaddition reaction between singlet silylene carbene and acetone has been investigated with CCSD（T）//MP2/6-31G method. From the potential energy profile, it can be predicted that the reaction has two competitive dominant reaction pathways. One consists of two steps： （1） the two reactants （R1, R2） firstly form a four-membered ring intermediate （INT4） through a barrier-free exothermic reaction of 585.9 kJ/mol; （2） Then intermediate （INT4） isomerizes to CH3-transfer product （P4.1） via a transition state （TS4.1） with energy barrier of 5.3 kJ/mol. The other is as follows： on the basis of intermediate （INT4） created between R1 and R2, intermediate （INT4） further reacts with acetone （R2） to form the intermediate （INT5） through a barrier-free exothermic reaction of 166.3 kJ/mol; Then, intermediate （INT5） isomerizes to a silicic bis-heterocyclic product （P5） via a transition state （TS5）, for which the barrier is 54.9 kJ/mol. The presented rule of this reaction： the [2＋2] cycloaddition effect between the π orbital of silylene carbene and the π orbital of π-bonded compounds leads to the formation of a four-membered ring intermediate （INT4）; The unsaturated property of C atom from carbene in the four-membered ring intermediate （INT4） results in the generation of CH3-transfer product （P4.1） and silicic bis-heterocyclic compound （P5）.展开更多
基金ACKNOWLEDGMENT This work was supported by the National Natural Science Foundation of China （No.20273066）.
文摘The mechanism of the cycloaddition reaction of forming germanic bis-heterocyclic compound between singlet dichloro-germylene carbene and formaldehyde has been investigated with CCSD（T）//MP2/6-31G^＊ method, from the potential energy profile, we predict that the reaction has two competitive dominant reaction pathways. The presented rule of this reaction： the 2p unoccupied orbital of the C atom in dichloro-germylene carbene insert the π orbital of formaldehyde from oxygen side, resulting in the formation of intermediate. In the intermediate and between two reactants, because of the two bonding π orbital in dichloro-germylene carbene and formaldehyde have occurred [2＋2] cycloaddition reaction, forming two four- membered ring compounds in which Ge and O are in the opposite orientation and in the syn-position, respectively. Because of the unsaturated property of C atom from carbene in the two four-membered ring compounds, they further reacts with formaldehyde, resulting in the generation of two germanic bis-heterocyclic compounds.
文摘The mechanism of the cycloaddition reaction of forming a silicic bis-heterocyclic compound between singlet dimethylmethylenesilylene （Me2C=Si：） and ethene has been investigated with the CCSD（T）//MP2/6-31G＊ method. From the potential energy profile, it can be predicted that, this reaction has one dominant channel. The presented rule of this dominant channel： the 3p unoccupied orbital of Si in dimethylmethylenesilylene and the π orbital of ethene forming the π→p donor-acceptor bond, resulting in the formation of three-membered ring intermediate （INT1）; INT1 then isomerizes to a four-membered ring silylene （P2）, which is driven by ring-enlargement effect; due to sp3 hybridization of Si atom in P2, P2 further combines with ethene to form a silicic bis-heterocyclic compound.
文摘The mechanism of the cycloaddition reaction between singlet dimethyl-silylene carbene and acetone has been investigated with density functional theory, From the potential energy profile, it can be predicted that the reaction has two competitive dominant reaction pathways. The presented rule of this reaction： the [2＋2] cycloaddition effect between the πorbital of dimethyl-silylene carbene and the π orbital of π-bonded compounds leads to the formation of a twisty four-membered ring intermediate and a planar four-membered ring product; The unsaturated property of C atom from carbene in the planar four-membered ring product,resulting in the generation of CH3-transfer product and silicic bis-heterocyclic compound.
基金supported by the National Natural Science Foundation of China(No.51102114)
文摘X2Si=Ge： （X = H, Me, F, CI, Br, Ph, Ar...） is a new species. Its cycloaddition reaction is a new area for the study of germylene chemistry. The mechanism of cycloaddition reaction between singlet state Me2Si=Ge： and formaldehyde has been investigated with the CCSD（T）//MP2/cc-pvtz method. From the potential energy profile, it could be predicted that the reaction has one dominant reaction pathway. The reaction rule presented is that the two reactants first form a four-membered Si-heterocyclic ring germylene through the [2＋2] cycloaddition reaction. Because of the 4p unoccupied orbital of Ge： atom in the four-membered Si-heterocyclic ring germylene and the π orbital of formaldehyde form a π→p donor-acceptor bond, the four-membered Si-heterocyclic ring germylene further combines with formaldehyde to form an intermediate. Because the Ge atom in the intermediate undergoes sp^3 hybridization after transition state, then the intermediate isomerizes to a spiro-Ge-heterocyclic ring compound involving Si via a transition state. The research result indicates the laws of cycloaddition reaction between HzSi=Ge： and formaldehyde. It has important reference value for the cycloaddition reaction between X2Si=Ge： （X = H, Me, F, CI, Br, Ph, Ar…） and asymmetric to-bonded compounds, which is significant for the synthesis of small-ring and spiro-Ge-heterocyclic compounds involving Si. The study extends research area and enriches the research content of germylene chemistry.
文摘The mechanism of cycloaddition reaction between singlet silylene carbene and acetone has been investigated with CCSD（T）//MP2/6-31G method. From the potential energy profile, it can be predicted that the reaction has two competitive dominant reaction pathways. One consists of two steps： （1） the two reactants （R1, R2） firstly form a four-membered ring intermediate （INT4） through a barrier-free exothermic reaction of 585.9 kJ/mol; （2） Then intermediate （INT4） isomerizes to CH3-transfer product （P4.1） via a transition state （TS4.1） with energy barrier of 5.3 kJ/mol. The other is as follows： on the basis of intermediate （INT4） created between R1 and R2, intermediate （INT4） further reacts with acetone （R2） to form the intermediate （INT5） through a barrier-free exothermic reaction of 166.3 kJ/mol; Then, intermediate （INT5） isomerizes to a silicic bis-heterocyclic product （P5） via a transition state （TS5）, for which the barrier is 54.9 kJ/mol. The presented rule of this reaction： the [2＋2] cycloaddition effect between the π orbital of silylene carbene and the π orbital of π-bonded compounds leads to the formation of a four-membered ring intermediate （INT4）; The unsaturated property of C atom from carbene in the four-membered ring intermediate （INT4） results in the generation of CH3-transfer product （P4.1） and silicic bis-heterocyclic compound （P5）.
