SULFURIC ACID-CATALYZED ALKYLATION OF BENZENE WITH HIGH MOLECULAR WEIGHT 1-ALKENES

1954 ◽  
Vol 19 (3) ◽  
pp. 463-468 ◽  
Author(s):  
W. L. LENNEMAN ◽  
R. D. HITES ◽  
V. I. KOMAREWSKY
Keyword(s):  
Molecular Weight ◽  
Sulfuric Acid ◽  
High Molecular Weight ◽  
Alkylation Of Benzene ◽  
Acid Catalyzed

Acetal Metathesis: Mechanistic Insight

Synlett ◽  
2019 ◽  
Vol 30 (17) ◽  
pp. 1971-1976
Author(s):  
Alexander G. Pemba ◽  
Stephen A. Miller
Keyword(s):  
Molecular Weight ◽  
Kinetic Study ◽  
High Molecular Weight ◽  
Equilibrium Distribution ◽  
Metathesis Reaction ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer ◽  
Metathesis Polymerization ◽  
Mechanistic Insight ◽  
Acid Catalyzed

The origins and recent applications of acetal metathesis are discussed in the context of synthesizing polyacetals via acetal metathesis polymerization (AMP). A kinetic study of the acid-catalyzed acetal metathesis reaction suggests the rate = k[H+][acetal]2, with MeOCH2OMe and EtOCH2OEt interchanging to yield MeOCH2OEt, achieving the statistical 1:2:1 equilibrium distribution in 4 hours at 80 °C and in 1 hour at 90 °C. Upon heating 1,10-decanediol and diethoxymethane, polydecylene acetal is formed with sequential distillation of ethanol, followed by diethoxymethane. A full mechanism for this polymerization is proposed, which begins with a transacetalization sequence to convert the diol into a bisacetal, followed by acetal metathesis to yield a high-molecular-weight polymer.

Microtubule motors and other maps

1990 ◽  
Vol 48 (3) ◽  
pp. 1-1
Author(s):  
Richard B. Vallee
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Cytoplasmic Dynein ◽  
Organelle Transport ◽  
Structural Components ◽  
Microtubule Associated Proteins ◽  
Microtubule Motors ◽  
Associated Proteins ◽  
The Subject ◽  
Intracellular Motility

Microtubules are involved in a number of forms of intracellular motility, including mitosis and bidirectional organelle transport. Purified microtubules from brain and other sources contain tubulin and a diversity of microtubule associated proteins (MAPs). Some of the high molecular weight MAPs - MAP 1A, 1B, 2A, and 2B - are long, fibrous molecules that serve as structural components of the cytamatrix. Three MAPs have recently been identified that show microtubule activated ATPase activity and produce force in association with microtubules. These proteins - kinesin, cytoplasmic dynein, and dynamin - are referred to as cytoplasmic motors. The latter two will be the subject of this talk.Cytoplasmic dynein was first identified as one of the high molecular weight brain MAPs, MAP 1C. It was determined to be structurally equivalent to ciliary and flagellar dynein, and to produce force toward the minus ends of microtubules, opposite to kinesin.

Studies on the Functionality of Newly Synthesized Fibrinogen after Treatment of Acute Myocardial Infarction with Streptokinase, Increase in the Rate of Fibrinopeptide Release

1993 ◽  
Vol 70 (06) ◽  
pp. 0978-0983 ◽  
Author(s):  
Edelmiro Regano ◽  
Virtudes Vila ◽  
Justo Aznar ◽  
Victoria Lacueva ◽  
Vicenta Martinez ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Molecular Weight ◽  
Steady State ◽  
High Molecular Weight ◽  
Coronary Arteries ◽  
Risk Index ◽  
Weight Fraction ◽  
High Molecular Weight Fraction ◽  
Fibrinopeptide A

SummaryIn 15 patients with acute myocardial infarction who received 1,500,000 U of streptokinase, the gradual appearance of newly synthesized fibrinogen and the fibrinopeptide release during the first 35 h after SK treatment were evaluated. At 5 h the fibrinogen circulating in plasma was observed as the high molecular weight fraction (HMW-Fg). The concentration of HMW-Fg increased continuously, and at 20 h reached values higher than those obtained from normal plasma. HMW-Fg represented about 95% of the total fibrinogen during the first 35 h. The degree of phosphorylation of patient fibrinogen increased from 30% before treatment to 65% during the first 5 h, and then slowly declined to 50% at 35 h.The early rates of fibrinopeptide A (FPA) and phosphorylated fibrinopeptide A (FPAp) release are higher in patient fibrinogen than in isolated normal HMW-Fg and normal fibrinogen after thrombin addition. The early rate of fibrinopeptide B (FPB) release is the same for the three fibrinogen groups. However, the late rate of FPB release is higher in patient fibrinogen than in normal HMW-Fg and normal fibrinogen. Therefore, the newly synthesized fibrinogen clots faster than fibrinogen in the normal steady state.In two of the 15 patients who had occluded coronary arteries after SK treatment the HMW-Fg and FPAp levels increased as compared with the 13 patients who had patent coronary arteries.These results provide some support for the idea that an increased synthesis of fibrinogen in circulation may result in a procoagulant tendency. If this is so, the HMW-Fg and FPAp content may serve as a risk index for thrombosis.

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