To alkanes Hydrogenation with a palladium or a platinum catalyst is the most common way of reducing alkenes. You may find our mechanism rather unsatisfactory, but it is hard to draw curly arrows for the reactions involved here. There is, however, plenty of evidence that the hydrogenation occurs like this, for example the alkene below reacts in such a way that the major product receives both hydrogen atoms on the same face of the molecule—just what we would expect from a reaction at a surface.

Hydrogenated vegetable oil

 Plants such as soya, rapeseed, cottonseed, and sunflower are useful sources of edible vegetable oils, but these oils are unsuitable as butter substitutes because of their low melting points. Their low melting points relative to animal fats are largely due to cis double bonds that disrupt the packing of the alkyl chains in the solid state. Treating the crude vegetable oil with hydrogen over a metal catalyst removes some of these double bonds, increases the proportion of saturated fat in the oil, and raises its melting point, making it suitable for making margarine.

The reaction is usually stopped before all the double bonds are hydrogenated, of course: margarine manufacturers are desperate to tell us that their products are still ‘high in unsaturated fatty acids’. Many also advertise that they are ‘low in trans unsaturated fatty acids’ because of a suggested link between incidence of coronary heart disease and trans unsaturated fatty acid intake.

Where have these trans double bonds come from? Well, partial hydrogenation can lead to significant double-bond isomerization, not just to regioisomers but to geometrical isomers too.

اخر الاخبار

اخبار العتبة العباسية المقدسة

المفرزة الطبية في الحزام الأخضر تقدم خدمات صحية للوافدين من العوائل العراقية

قسم الشؤون الخدمية ينهي أعمال غسل وتنظيف باب قبلة مرقد أبي الفضل العباس (عليه السلام)

بمشاركة أكثر من ألف طالب.. قسم الشؤون الفكرية يستعدّ لإطلاق المسيرة العاشورائية السنوية

لليوم الثالث.. قسم العلاقات العامة يواصل فعاليات مخيّم البذرة الواعدة

المزيد

الآخبار الصحية

نصائح عملية للحد من التعرق المفرط في الصيف

أطباء يحذرون: مكمل غذائي شائع قد يدمر الجهاز العصبي

تحذير طبي من تأثير جانبي "غير متوقع" لحقن التخسيس

حمامات الثلج قد تكون خطيرة وأحيانا مميتة.. ما السبب؟

المزيد

الآخبار التكنلوجية

أكبر جدارية شمسية في العالم تدخل موسوعة غينيس.. مشروع ضخم

تسارع دوران الأرض يثير القلق.. وتحذيرات من "كوارث محتملة" ؟

"سوذبيز" تطرح أكبر قطعة من المريخ على الأرض في مزاد علني

أوبن أيه آي تعتزم إطلاق متصفح إنترنت يعمل بالذكاء الاصطناعي

المزيد

مواضيع ذات صلة

Aziridine: ring strain promotes ring opening

Reactions of saturated heterocycles

More heteroatoms in fused rings mean more choice in synthesis

Quinolones also come from anilines by cyclization to an ortho position

Quinolines and isoquinolines

Pyrimidines can be made from 1,3-dicarbonyl compounds and amidines

Pyrazoles and pyridazines from hydrazine and dicarbonyl compounds

Thermodynamics is on our side

There are thousands more heterocycles out there

Fusing rings to pyridines: quinolines and isoquinolines

Putting more nitrogen atoms in a six-membered ring

Benzo-fused heterocycles-Indoles are benzo-fused pyrroles